Grid-Tied, Off-Grid and Hybrid Solar Systems

What are the benefits of grid-connected solar panels vs. living off the grid? Deciding whether or not to grid-tie your solar panels is usually pretty straightforward – the clear-cut benefits of being grid-tied appeals to the majority of homeowners. There are, however, some people that choose to live off the grid.

What would be the best in your situation? Let`s look closer at the benefits and downsides of grid-tied, off-grid and hybrid solar systems.

 

Grid-Tied Solar Systems

Grid-tied, on-grid, utility-interactive, grid intertie and grid backfeeding are all terms used to describe the same concept – a solar system that is connected to the utility power grid.

Grid-tied solar system

 

Advantages of Grid-Tied Systems

1. Save more money with net metering

A grid-connection will allow you to save more money with solar panels through better efficiency rates, net metering, plus lower equipment and installation costs:

Batteries, and other stand-alone equipment, are required for a fully functional off-grid solar system and add to costs as well as maintenance. Grid-tied solar systems are therefore generally cheaper and simpler to install.

Your solar panels will often generate more electricity than what you are capable of consuming. With net metering, homeowners can put this excess electricity onto the utility grid instead of storing it themselves with batteries.

Net metering (or feed-in tariff schemes in some countries) play an important role in how solar power is incentivized. Without it, residential solar systems would be much less feasible from a financial point of view.

Many utility companies are committed to buying electricity from homeowners at the same rate as they sell it themselves.

 

2. The utility grid is a virtual battery

Electricity has to be spent in real time. However, it can be temporarily stored as other forms of energy (e.g. chemical energy in batteries). Energy storage typically comes with significant losses.

The electric power grid is in many ways also a battery, without the need for maintenance or replacements, and with much better efficiency rates. In other words, more electricity (and more money) goes to waste with conventional battery systems.

According to EIA data[1], national, annual electricity transmission and distribution losses average about 7% of the electricity that is transmitted in the United States. Lead-acid batteries, which are commonly used with solar panels, are only 80-90% efficient at storing energy, and their performance degrades with time.

Additional perks of being grid-tied include access to backup power from the utility grid (in case your solar system stop generating electricity for one reason or another). At the same time you help to mitigate the utility company`s peak load. As a result, the efficiency of our electrical system as a whole goes up.

 

Equipment for Grid-Tied Solar Systems

There are a few key differences between the equipment needed for grid-tied, off-grid and hybrid solar systems. Standard grid-tied solar systems rely on the following components:

  • Grid-Tie Inverter (GTI) or Micro-Inverters
  • Power Meter

 

Grid-Tie Inverter (GTI)

What is the job of a solar inverter? They regulate the voltage and current received from your solar panels. Direct current (DC) from your solar panels is converted into alternating current (AC), which is the type of current that is utilized by the majority of electrical appliances.

In addition to this, grid-tie inverters, also known as grid-interactive or synchronous inverters, synchronize the phase and frequency of the current to fit the utility grid (nominally 60Hz). The output voltage is also adjusted slightly higher than the grid voltage in order for excess electricity to flow outwards to the grid.

 

Micro-Inverters

Micro-inverters go on the back of each solar panel, as opposed to one central inverter that typically takes on the entire solar array.

There has recently been a lot of debate on whether micro-inverters are better than central (string) inverters.

Micro-inverters are certainly more expensive, but in many cases yield higher efficiency rates. Homeowners who are suspect to shading issues should definitely look into if micro-inverters are better in their situation.

 

Power Meter

Most homeowners will need to replace their current power meter with one that is compatible with net metering. This device, often called a net meter or a two-way meter, is capable of measuring power going in both directions, from the grid to your house and vice versa.

You should consult with your local utility company and see what net metering options you have. In some places, the utility company issues a power meter for free and pay full price for the electricity you generate; however, this is not always the case.

 

Off-Grid Solar Systems

An off-grid solar system (off-the-grid, standalone) is the obvious alternative to one that is grid-tied. For homeowners that have access to the grid, off-grid solar systems are usually out of question. Here`s why:

To ensure access to electricity at all times, off-grid solar systems require battery storage and a backup generator (if you live off-the-grid). On top of this, a battery bank typically needs to be replaced after 10 years. Batteries are complicated, expensive and decrease overall system efficiency.

Off-grid solar system

 

Advantages of Off-Grid Solar Systems

1. No access to the utility grid

Off-grid solar systems can be cheaper than extending power lines in certain remote areas.

Consider off-gird if you’re more than 100 yards from the grid. The costs of overhead transmission lines range from $174,000 per mile (for rural construction) to $11,000,000 per mile (for urban construction).[2]

 

2. Become energy self-sufficient

Living off the grid and being self-sufficient feels good. For some people, this feeling feeling is worth more than saving money. Energy self-sufficiency is also a form of security. Power failures on the utility grid do not affect off-grid solar systems.

On the flip side, batteries can only store a certain amount of energy, and during cloudy times, being connected to the grid is actually where the security is. You should install a backup generator to be prepared for these kinds of situations.

 

Equipment for Off-Grid Solar Systems

Typical off-grid solar systems require the following extra components:

  • Solar Charge Controller
  • Battery Bank
  • DC Disconnect (additional)
  • Off-Grid Inverter
  • Backup Generator (optional)

 

Solar Charge Controller

Solar charge controllers are also known as charge regulators or just battery regulators. The last term is probably the best to describe what this device actually does: Solar battery chargers limit the rate of current being delivered to the battery bank and protect the batteries from overcharging.

Good charge controllers are crucial for keeping the batteries healthy, which ensures the lifetime of a battery bank is maximized. If you have a battery-based inverter, chances are that the charge controller is integrated.

 

Battery Bank

Without a battery bank (or a generator) it’ll be lights out by sunset. A battery bank is essentially a group of batteries wired together.

 

DC Disconnect Switch

AC and DC safety disconnects are required for all solar systems. For off-grid solar systems, one additional DC disconnect is installed between the battery bank and the off-grid inverter. It is used to switch off the current flowing between these components. This is important for maintenance, troubleshooting and protection against electrical fires.

 

Off-Grid Inverter

There`s no need for an inverter if you`re only setting up solar panels for your boat, your RV, or something else that runs on DC current. You will need an inverter to convert DC to AC for all other electrical appliances.

Off-grid inverters do not have to match phase with the utility sine wave as opposed to grid-tie inverters. Electrical current flows from the solar panels through the solar charge controller and the bank battery bank before it is finally converted into AC by the off-grid-inverter.

 

Backup Generator

It takes a lot of money and big batteries to prepare for several consecutive days without the sun shining (or access to the grid). This is where backup generators come in.

In most cases, installing a backup generator that runs on diesel is a better choice than investing in an oversized battery bank that seldom gets to operate at it`s full potential. Generators can run on propane, petroleum, gasoline and many other fuel types.

Backup generators typically output AC, which can be sent through the inverter for direct use, or it can be converted into DC for battery storage.

 

Hybrid Solar Systems

Hybrid solar systems combines the best from grid-tied and off-grid solar systems. These systems can either be described as off-grid solar with utility backup power, or grid-tied solar with extra battery storage.

If you own a grid-tied solar system and drive a vehicle that runs on electricity, you already kind of have a hybrid setup. The electrical vehicle is really just a battery with wheels.

Hybrid solar system

 

Advantages of Hybrid Solar Systems

1. Less expensive than off-gird solar systems

Hybrid solar systems are less expensive than off-grid solar systems. You don`t really need a backup generator, and the capacity of your battery bank can be downsized. Off-peak electricity from the utility company is cheaper than diesel.

 

2. Smart solar holds a lot of promise

The introduction of hybrid solar systems has opened up for many interesting innovations. New inverters let homeowners take advantage of changes in the utility electricity rates throughout the day.

Solar panels happen to output the most electrical power at noon – not long before the price of electricity peaks. Your home and electrical vehicle can be programmed to consume power during off-peak hours (or from your solar panels).

Consequently, you can temporarily store whatever excess electricity your solar panels in batteries, and put it on the utility grid when you are paid the most for every kWh.

Smart solar holds a lot of promise. The concept will become increasingly important as we transition towards the smart grid in the coming years.

 

Equipment for Hybrid Solar Systems

Typical hybrid solar systems are based on the following additional components:

  • Charge Controller
  • Battery Bank
  • DC Disconnect (additional)
  • Battery-Based Grid-Tie Inverter
  • Power Meter

 

Battery-Based Grid-Tie Inverter

Hybrid solar systems utilize batter-based grid-tie inverters. These devices combine can draw electrical power to and from battery banks, as well as synchronize with the utility grid.

 

The bottom line is this: Right now, for the vast majority of homeowners, tapping the utility grid for electricity and energy storage is significantly cheaper and more practical than using battery banks and/or backup generators.

Author:

Comments

  1. Shady Abeid says

    Hi Mathias, I like your website.

    I have an idea that I am struggling to find any resources to back it. First of all I graduated last year with master in renewable energy from Warsaw university of technology. I work currently in the UK, but very soon will be returning to Poland as my employer is going under. Before I tell you about my idea, we can agree that there are 3 main types of domestic solar systems;

    1- grid tied
    2- stand alone system
    3- Hybrid which is actually grid tied with battery back

    You mentioned these three types in your article. Now in order to have grid tied or hybrid system you need to know that your utility company will buy the excess energy otherwise you will b dumbing this energy for free in the grid right?

    then what is the solution for a country that yet to adopt any feed in tariff system (like Poland)?. the only solution then is stand alone. but we know that such systems are extremely expensive if they are to supply a normal size house throughout the year. The reason is that we have to build a very large system to provide enough power during winter.

    Now my idea is to build a system that stands alone, but have the flexibility to switch over to utility power when we run out of juice. The system that I am thinking of should be sized to provide all the energy that a house needs during the best irradiation day in the year. the system like any stand alone system consists of panels batteries, inverter, and a new component is Automatic Transfer Switch, which is going to to switch over to grid power once the inverter shuts down. I ran few simulation for such a system and find that it works fine. The advantage of this system is:

    1- you need minimal amount of PV panels
    2- you don’t need large battery bank as in stand alone systems
    3- most importantly its very reliable compared to stand alone

    sizing the system to highest irradiation day in the year means that, the system can’t provide all the energy needs for mare than few days, the simulation results showed that such a system provide about 50% of the annual electricity needs of a house in the Polish climate.

    I can’t find any resources that could support my idea, therefore I am afraid that I am missing some basic information that makes this system unusable.

    Thanks for reading such a long reply. and let me know if you have any objection to this idea

    • Mathias says

      Glad you liked the article.

      “Now in order to have grid tied or hybrid system you need to know that your utility company will buy the excess energy otherwise you will b dumbing this energy for free in the grid right?”

      Unless you store the energy in batteries.

      The way I understand your system it is scaled to never generate more electricity than what you need on a day-to-day basis and therefore you save money by not needing a big battery bank. I think it sounds reasonable, but a system like this could only cover a tiny of a household’s yearly electricity needs.

      • Sudershan Gosain says

        Dear Sir,

        I want to buy two grid solar panel & inverter for office and residence. My requirement for home is 8 fans, fridge, 8 florescent bulbs, instant geyser. What will it cost. That it costs, guarantee, and after sales service will be available.?with regards,
        Sincerely yours,

        Sudershan Gosain

      • Harold says

        Hello Mathias,
        regarding the grid tie in Poland,
        Would it be reasonable to just install the standard hybrid system with a little more battery capacity and also divert energy to some usefull work that can be used later? for example a huge 100 gallon pre heat water tank.
        Maybe you could supply free hot water to all of your neighbors instead of giving the grid free power!
        Or any other use that would benefit people around you. Some kind of machine that does work like pumping water to garden area or extra air conditioning or heating in a room you usually don’t use.
        Install a driveway heating system just for use when the sun is producing more than you can use. anything other than feeding back into the grid for free.!

      • Joe says

        Mathias,
        I am in the beginning stages of designing a similar system. My intent is to build the system to charge a battery bank that I will attempt to build myself. I am gathering data now to build my own deep cycle batteries. The reason I am not going completely off the grid right away is that I do not know if I have enough South-facing rooftop to accommodate the required panel surface area. I figure if I make the investment in an automatic transfer switch I can use it now to backup my system with the public grid until I can afford to “grow” the solar setup and supplement with wind turbine power in the future, hopefully generating enough power to tell the utility company to piss off for good. At that point I will re-purpose the automatic transfer switch for a different type of backup power for emergency only. I reside in the Northeastern USA and have a small farm. Usually when the days are cloudy there is plenty of wind in place of the sun, making the turbines a natural choice. I have a good idea of my current load requirements, but as I build my system larger I intend to start using more electric appliances and eliminate the need for natural gas that I have now as well. I’m not sure about charge controller and inverter size. I currently have a 100A 110/220V service, but I will likely be upgrading to 200A as a part of this project. Please let me know if you have any recommendations for good equipment that I could purchase to make this system work. Thanks, Joe

    • Stuart Hawker says

      Mathias,
      Hello and like your comments.
      My question is a little diferant.
      I have an off grid system on my farm.
      6KW solar (2 x 3kw controllers and 1 x 10KW inverter 120vdc -240vac)
      Can i add an “ON-grid” solar inverter to system?
      The current solar, inverter and battery are housed 300mtr away from house i am building.
      I want to put more panels on new house (2.5KW)
      Will the ON-grid system tie in to current OFF grid inverter.
      Can any damage be done?
      Stuart

    • says

      Hi Mathias,
      Take a look at the PowerRouter works on or off grid with or without batteries and has
      remote web monitoring and battery management as standard. ps by managing the batteries properly you’ll significatly extend their life. Jenny @ 2020 Solar

    • Imran says

      hi i hope would have find the reliable source for your idea Axpert inverters are the best option you can run your load all the with solar panels at sun set it switches to your grid and in case of emergencies no gird power you will have the batteries to run your load.
      its a pure hybrid inverter

  2. Matjaz says

    @Shady Abeid: I also surfed the web to support your idea, but from my thinking (very very unprofessional) best connection is:
    1) PV–>inverter –> power meter for solar plant –> grid
    2) PV–>inverter –> after power meter of household –> home appliance
    3) grid–> power meter of household –> home appliance

    As you can see, there are two outputs of Inverter and home appliance has two inputs. Problem I see is that electricity can run from grid (3) into power meter for solar plant (1). There must be one way only connection and I doubt grid operator will allow that connection.
    After all, grid operator loses two fees… one for distributing solar electricity from you and second is for distributing gird electricity to you… although you are buying back own electricity. Can somebody support that idea?

  3. adri says

    Hey Mathias,

    great article and thank you.

    I was wondering what do you suggest is the most expensive system component apart from the solar cells.

    I feel batteries are expensive but I might be completely wrong. I would very helpful if you could enlighten me please.

  4. Johnny says

    Is there a solar system that runs like an off grid system that only utilizes the grid when the storage batteries run low? Not a battery back up system. Use battery power at night, solar power by day, and the grid only when your battery supply is low. Maybe a battery back up system could mimic this by just disconnecting from the grid at night effectively causing a “grid outage” causing switch over to the battery power then reconnecting to the grid in the morning. I am asking is there a setup that does this automatically?

  5. Fabian says

    Hi Mathiyas,
    I am designing a Solar/Grid hybrid system with battery back-up for my home. My aim is to make solar is the primary source and the grid is the secondary source for my loads. Well, In my place power blackout occurs so often and here it’s not possible to deploy grid tied solar system. I don’t want to use the solar panels just to charge the batteries. I want to use energy from solar for my home appliances as well as charging battery banks also. The inverter should be able to disconnect the grid during grid failure. Can u please help me choosing the type of inverter and battery banks?
    Fabian(India)

  6. Sam says

    Hi
    I’m an apprentice electrician in Queensland, the company I work for is looking for a system such as Johnny is asking about. With the current buying price of energy being so high and feed in price being so low, we need a system that can charge a battery bank for the house to use during peak hours, feed back to the grid once the battery bank is full and also connect back to the grid when the bank is nearly empty.

  7. Sudheer says

    By the way guys reading this site:
    by solar – mains hybrid UPS system, i mean:

    a) When PV power is available, AC loads run on it.
    b) When PV not enough loads automatically switch over to GRID supply and in case GRID supply not proper or no supply, the AC loads run on battery bank inverted to pure sine wave AC.

    *All this switching is automatic and no user intervention required*

    battery bank can be charged on PV power or GRID power, PV powering preference given to supplying load first and any excess power available will be used to charge battery bank.

    sudheersrivastav@rediffmail.com

    • Sudheer says

      Dear Sam from QLD, Marc, Shady Abeid from Poland and all others interested in this Solar – Mains Hybrid Power system:
      Please contact me at the below mentioned mail id’s:
      sudheersrivastav@rediffmail.com

      Many people are requesting about this kind of system and are very enthusiastic about achieving this type of product implementation…

      I have a very good concept and design.

      I am an Electronics & Instrumentation Engineer with good experience in Analysis, Design & Implementation of Solutions for any requirement. I am also a Microsoft & Cisco certified IT professional. I have worked as a Project Engineer – Infrastructure Rollout/Management with 8 yrs of experience.

      Other than that I am an avid researcher of Alternative Energy Technologies and Alternative Propulsion Systems.

      By Alternative Energy Technologies, i DO NOT mean Solar/Wind/Geothermal etc (i have in my mind an entirely different concept of alternative energy tech) BUT at present Solar Power is the only Alternative Energy Technology which the alternative energy technology Suppressors will allow people to use because they consider that it cannot outrun people’s dependence on Oil & Gas as solar panels haven’t even touched the 50% conversion efficiency mark.

      The reason why I am contacting all of you is because i want to design, implement and market a product which will make solar power a cost-effective viable option for everyone to use.

      Presently the solar power products sold in the market demands a higher battery bank capacity for supporting larger loads for longer time and solar power is used ONLY FOR CHARGING OF BATTERY BANK and not powering AC loads directly.

      “I don’t see any sense in converting solar energy to electrical energy, then to chemical energy by storing in batteries, and then back to electrical energy via DC-AC inverters”

      Grid-Synchronous Solar Inverters are not great because as per the regulation laid down by Power Companies, they must power down when the grid supply fails….which means they can’t be used when grid supply is down…this contradicts the very meaningful usage of solar power!

      I have searched all over the Internet and the above mentioned systems only are sold. I have tried contacting some mass production centers in Mainland China for mass producing my concept according to the excellent design specifications i have made, but none are yet up to the point of being able to understand the efficiency of the direct energy conversion system such as the one I am talking about.

      Then I searched more vigorously and found this blog and i am thrilled that I am not alone in this thought process of wanting to make a high-efficiency direct conversion solar power system.

      I am looking for like minded professionals/Organizations/VC’s who are interested and very serious about this Solar-Mains Hybrid Energy System design, development and marketing on a very large scale basis and also exporting the product to other potential markets across the world.

      “WE NEED TO DECREASE THE DEPENDANCE ON THE FOSSIL FUELS/GRID POWER FOR THE SAKE OF REDUCING OUR ELECTRIC BILLS AND ALSO TO MASSIVELY REDUCE THE POLLUTION DUE TO BURNING OF FOSSIL FUELS FOR GENERATION OF ELECTRIC POWER.”

      I have a very good concept for the Solar-Mains Hybrid Power System to design it from scratch and I also know the exact parametric design methodology to ensure the highest possible efficiency and cost-effectiveness of this system.

      (High-efficiency Inverter design, precise Solar MPPT design, fully automatic transfer between solar/grid/battery operating modes, Load Detection & Management to restrict battery bank size to bare minimum, battery chemistry suitable for solar and design of charger suitable for most efficient charging etc)

      I am eagerly waiting for a response.

      Regards,
      Sudheer

  8. Christian says

    Hallo guys
    I have moved to south africa where laws on grid-tie not are like in europe. we are not allowed to feed electricity back to the grid at all. So people build stand alone systems. Im trying to find an inverter with an intern switch, that can use my power from my panels and batteries. And when night falls it must be able to switch to the grid automaticly. But never feed electricity back to the grid. Can anyone show me a website with that kind of inverter?
    You can also check this link to see what i mean. The only problem with the picture on this link is that the system feeds overproducing electricity back on the grid. http://www.clevertec.co.za/Figure_2.html

    Regards
    Christian

    • sudheer srivastav says

      Hey Christian,
      Google the thing dude! South Africa is one place which adopts latest technologies much quicker than the rest of the world….so the kind of thing you want would surely be available there. Here’s one link which has a Solar UPS with a AC transfer switch….which means it transfers load between AC mains and Solar power.

      http://www.bluesunenergy.co.za/products.php?catID=22&cat=UPS/SOLAR%20UPS

      What you need is a “DC to AC Inverter with LOAD TRANSFER Switch”

    • Mike says

      Hi Christian,
      i am also in SOuth Africa and i use a Bi Directional inverter to do just that. My panels chanrge my batteries and run half my home, if the batteries go to 30% DoC then the inverter switches automatically over to Eskum..

  9. sudheer srivastav says

    Everyone reading this Blog,

    First of all we have to says Kudos to Mathias!

    If not for him having taken time to create this blog and give the information which created interest in folks like us….all this information exchange and discussion would not be taking place.

    Thank You Very Much Mathias.

    regards,
    Sudheer

    sudheersrivastav@rediffmail.com

  10. s.k.vinod kandan says

    Hi, i am looking for Solar Off grid inverter from countries within europe also as per european standards,the range is from 1KW – 10KW.So can you refer any reputed company.

    • sudheer says

      Hi Vinod,
      are you looking for solar inverters to install them for customers in europe or do you want to import solar inverters from europe? where are you located? Have you considered the fact that a solar hybrid system is way much efficient and extremely cost-effective than a pure off-grid system?

      regards,
      Sudheer.

      sudheersrivastav@rediffmail.com

  11. sudheer says

    Hi Mathias, Shady Abeid, Sam, Matjaz and everyone
    “WISH YOU ALL A VERY HAPPY NEW YEAR”

    I am feeling very enthusiastic about 2013 and hoping that the need for designing a direct conversion solar mains hybrid power system will be felt more than ever. I am calling upon all those people/professionals with advanced electronics knowledge and those electronic design engineers with access to high-end electronic CAD simulation software to achieve this goal. I am hoping for a good response in this year 2013.

    Regards,
    Sudheer.

    sudheersrivastav@rediffmail.com
    sudheersrivastav.s@gmail.com

    • A RAMMOHAN REDDY says

      Dear Sudheer,
      A VERY HAPPY NEW YEAR TO YOU.

      The concept you had in mind is one of the best what Indians need at this time.

      I live in Andhra Pradesh and I am very much interested to know more about your concept of
      PV to loads, in case of inadequacy of PV then Grid and in case of Grid power cut then battery bank to loads.
      If you have developed a suitable inverter or know about someone who has one of this type, I request you to share the same with me.

      Thanks

      RAMMOHAN

      • Tim Chapman says

        I think the Outback “Radian” series of inverter would work for this application….only drawback I can find is that the battery bank should be close to the inverter itself – don’t think my wife would go for batteries in the family room….

  12. Paul Russell says

    Everyone is talking about storing excess solar electricity in secondary electrical cells but there are other ways to store energy. There is a solar thermal power plant in Spain that collect solar energy using parabolic troughs that are focused on oil filled tubes, the hot oil is then used to produce steam or to heat molten salt, storing the heat for later use. Other ways that utilities store electricity is to use it to pump water up to a higher elevation and, when the energy is needed, let it flow back down through a turbine. There is also mechanical storage using flywheels or as a pressurised hydraulic liquid or compressed gas. Or, in my opinion, converting the electricity into a storable, chemical fuel that can then be used in a engine, such as Hydrogen through the electrolysis of water, however H2 can be difficult fuel to store and use, so, better yet, use the H2 to produce Methane, the chief component of Natural Gas & Biogas, a fuel made to the rotting of organic matter in low-O2 environment, by combining it with CO2, for the Biogas, for example, using the Sabatier process. H2O produced during the process and the combustion of the Methane can go back into the electrolyzer and the CO2 can be recycled through the process. Oxygen produced during electrolysis can be either dumped or used to combustion of the Methane in a pure O2 environment, lowering NOx emissions

  13. sudheer says

    unable to post reply….some error creeps up saying:

    “we cant find the page you are looking for, press back button or goto homepage”

      • sudheer says

        Hi Mathias,
        i am glad to receive a message from you. Well i don’t know the exact reason( maybe it’s a character limit, paragraph limit or something) but i am not able to post my complete reply to those reading this blog and asking if i made an inverter or know someone who made it. Till now i have been able to post only half of my detailed reply.

        I am trying to make people understand of the new concept of direct energy conversion to avoid huge battery bank and also hoping to get in touch with electronic design professionals (such as shady abeid) with access and expertise in electronic CAD simulation software, so that i can come up with a solar-mains hybrid power system which is 98% efficient and does the required job.

  14. sudheer says

    Dear All,
    I would like to clarify something. I am receiving many emails and posts asking me if I made some inverter or if I know someone who made it.
    First of all I would like to point out that the word “Inverter” is being used very loosely. If by that you mean a large black box which hooks on to a couple of batteries and wires run to the mains panel in your home and it beeps when there is a power cut…..NO IAM NOT MAKING THAT AGE OLD INVERTER STUFF.

    What I made is a SOLAR-MAINS HYBRID POWER SYSTEM. Please don’t call it as an Inverter or compare it with the crappy inverter stuff available in market.
    My device has the following sectional blocks:

    1) Solar Panel Array Output Conditioner: This is the first section which takes the varying output from Solar Array and makes sure that it’s steady and the maximum possible power is being drawn from the solar panel at any given time between reasonable limits of Dawn & Dusk. (Maximum Power Point Tracking)

    2) Second stage is an Inverter circuit (it is an IGBT based electronic inverter circuit. Don’t confuse the word “Inverter” with a big box sold in the market and which is hooked to batteries).

    The inverter stage is unlike ordinary ones and accepts different range of voltages from either a solar array output conditioner or battery bank. Normally you would need 2 inverter stages (which increases cost significantly) one for solar array and one for battery bank but I figured out a method to merge both together into one single module/section to reduce cost and duplicity of components.

    3) Third stage is a microprocessor based precision battery bank charger which also alerts if there is a failure in battery bank. You need to write a program in “C” or better in Assembly Programming Language for that microprocessor to execute commands faster.

    4) The fourth stage is a Load Control and Management circuit. It senses when the solar array output is enough to run the LOAD and connects the LOAD to it. When solar output drops or load increases beyond solar output handling capability, it connects LOAD to MAINS. When both solar and grid power are not available, the MINIMAL BATTERY BANK powers critical loads such as computer etc. Also this system is designed to run few ceiling fans and tube lights etc overnight. Let’s say there is a power cut from 10PM tonight till 7AM next morning….you can have at least two ceiling fans running for a comfort sleep with a minimal low cost battery bank.

    So in my design, there is no huge battery bank stage. Hence it is a direct energy conversion system which is the best possible for a low cost solar-mains hybrid power system. Currently I planned this system to be able to provide upto 4kW of power. So it will be able run LCD TV’s, Refrigerators, Ceiling Fans, Tube Lights and Washing Machine etc simultaneously upto 4kW max. Minimal battery bank will provide backup only to smaller loads like ceiling fans, LCD TV, Desktop Computer etc and not to washing machine or refrigerator. All this segregation of large inductive loads and critical loads will be taken care of by the device without any human intervention.

    I have a design which is about 75% efficient. I am trying to select new and latest components from various Semiconductor and Power MOSFET manufacturers…..trying to simulate the revised versions with electronic CAD simulation software and come up with a final version of the device which has a 98% efficiency. The Electronic CAD software are expensive (USD 5000), there are many simulation models file formats and I need to have access to these to get the job done. The only person in this forum who claims to have run simulations has still not responded to my messages to him and neither do I have his direct contact details.

    If anyone can search and find a device in the market which does exactly what I described above….please be my guest. I’ve been searching for more than 3 months and I am sure no such device is available in the market…that was the reason why I took up this project. I have already mentioned in my latest post that I am expecting response from electronic design professionals having knowledge and access to such software’s so that I can come up with the final solution after running simulations using those software.

    I have no argument with those who mailed me saying:
    “We can buy solar panels, an Inverter, a battery charger which are commonly available in the market and assemble them all to make the device you are talking of”
    Well if anyone can just buy those individual devices and hook them up and do exactly what I said for USD 300-500 (excluding cost of solar panel array), with an efficiency of 98% and not to mention the complete automated load segregation and management (0% human intervention), once again please be my guest.

    Guys, I am struggling to get access to those expensive high-end software, be able to open all those various electronic components simulation model file formats from different manufacturer websites and run those simulations to achieve a final revision with 98% efficiency! Any help will be deeply appreciated.

    sudheersrivastav@rediffmail.com

    • says

      Hi, Sudheer

      Did you find the CAD yet? Fusion 360 is available for Windows 7/8 (64-bit) and OS X for free until September. Around 25 USD/month after that.

      Should work for your needs, but learning it takes some time.

      • Sudheer Srivastav says

        Hi Asko,

        Fusion 360 is an Engineering CAD software meant for mechanical/civil design and not for electronics design. I know the needed software but there are some issues as I explained earlier in the blog that I need various component simulation file formats suitable for some particular simulators such as OrCAD, Altium Designer etc and also the trial versions do not have the required functionality. These software cost upward of USD 5000. Trial versions get us nowhere as far as these simulators as concerned.

        This research and design work cannot be done on home notebooks and makeshift 100 sq feet rooms. It requires a SMALL but DECENT R&D lab setup which no one seems to understand. I keep getting emails from many people who are business oriented, even CEO’s but all they ask is whether the product is ready to use and how much profit will it fetch. Even the creams in a facial kit or Revlon Lipstick is a product of years of fine R & D and these people who contacted me expect a product which will resolve our energy crisis without R & D . These are the stumbling blocks I am facing. I’ve walked them thru the process and explained in detail that it won’t take millions of dollars and years but just maybe around 6 months of intense application and improvising of research already done by me to build the ultimate refined product. What I observe is basically no one seems to be interested in even a small amount of R&D without which obviously nothing will ever succeed.

        regards,
        Sudheer

        sudheersrivastav@rediffmail.com

  15. MANUEL RIOSECO O says

    I have a off-grid hybrid wind and solar system. Is there any possibility to convert a off-grid to a on-grid system

    • Sudheer says

      Dear Manuel,
      what exactly do you mean by off-grid to on-grid conversion?
      If you mean that once your off-grid battery bank runs out of juice, you would like the system to revert to using grid power. Yes, that can be simply done.

      All you need is a 110 or 230VoltAC DPDT(Double Pole Double Throw) Power Relay rated for your total load amperes.

      I don’t know how to post a circuit diagram here but will be glad to email it to you.

      Brief Explanation:
      Your off-grid Inverter “Live” and “Neutral” terminals are connected to this Power Relay Coil and also to one contact each of the double poles. Grid Input’s “Live” and “Neutral” terminals coming from your house circuit breaker are connected to the other two respective poles. The “LOAD” is connected to the common terminals of the relay poles.

      (THOUGH THIS IS A SIMPLE TASK, I REQUEST YOU TO TAKE HELP OF QUALIFIED ELECTRICAL PERSONNEL TO DO THIS WIRING TO PREVENT RISK OF SHORT-CIRCUIT AND DEATH/INJURY)

      When your off-grid inverter is supplying power, the relay coil is energized and connects your house “LOAD” to itself. When your off-grid Inverter stops because battery bank ran out of juice, the relay coil is de-energized and “LOAD” gets connected to Grid Mains Input. This means 0% human intervention.

      (ALWAYS TREAT ELECTRICITY WITH RESPECT OR ELSE IT MIGHT GET YOU KILLED)

      Here is a link for the relay:
      http://www.rapidonline.com/Electronic-Components/DPDT-10a-Power-Relay-230v-Ac-60-1676

      You can buy one from Ebay or preferably from a local electrical & hardware store.

      regards,
      Sudheer

      sudheersrivastav@rediffmail.com

  16. sudheer srivastav says

    “IS THE BENEFIT OF HAVING A GRID TIED (GRID SYNCHRONIZED) SOLAR INVERTER ONLY THAT WE CAN FEED BACK POWER TO THE GRID AND ENJOY NET METERING BENEFIT?”

    Dear All,
    It’s been a while since I posted new information. I was off the blog due to some critical work and was busy researching and figuring out the best converters and charger topology/configuration solution for the solar project.

    I’ve been receiving emails about solar inverters and I see a lot of confusion about their types, benefits and which would be the best for our present day application. There are basically three types of Solar Inverters:

    1) Off-Grid Inverter

    This is the traditional inverter type which has a solar charge controller charging a “LARGE BATTERY BANK” that supplies power to a DC-AC inverter which enables us to run AC loads. So there is an “INTERMEDIATE STEP” of solar to chemical energy conversion involved in this process. The batteries are always involved in the energy conversion process. This type of inverter works only as long as the batteries have some charge left in them. There is no connection to the GRID and this system goes dead once “Low Battery” is reached. The large battery bank (MOST EXPENSIVE PART OF THE OFF-GRID SYSTEM) is a necessary evil to ensure a steady/smooth output from the Inverter to the AC loads even under a significantly varying Solar Irradiation condition.

    2) On-Grid Inverter

    This is the same as an off-grid inverter but a simple DPDT (Double Pole Double Throw) AC Power Relay is connected at Inverter output and as soon as “Low Battery” is reached and Inverter shuts down, the AC Loads are re-connected to the GRID. This way the LOADS have an uninterrupted supply of power and chances of total blackout is quite less.
    In my last post dated: February 12, 2013 @ 10:47 am, I have explained about this arrangement for the simple automated switching without human intervention.

    3) Grid Tied (Grid Synchronized) Inverter

    Here comes the most interesting part of solar power harnessing to get usable 120/230VAC electric power. The Grid Tied Inverter has its OUTPUT synchronized to the FREQUENCY (exactly same), PHASE (exactly same) and VOLTAGE (slightly higher for feeding power into GRID and also powering the LOAD) of the GRID. The output of the Inverter and Grid Supply are literally paralleled and connected to the Load.

    “WHAT IS THE BEST BENEFIT WE OBTAIN FROM SUCH AN ARRANGEMENT?”

    Let me cite an example to you. Say we have a 4.5KiloWatt Peak Solar Array which is connected to a Grid Synchronized Inverter. Let’s assume its 7:30AM in the morning and you are using a LOAD of 1.8KiloWatt. Also let’s assume that the Solar Array is able to provide just about 600Watts of power at the time of day. Without a large battery bank as in an off-grid system, we cannot simply run the LOAD on PV alone isn’t it? But a large battery bank is pretty expensive in terms of initial cost and maintenance/replacement batteries cost. So this Grid Synchronized Inverter eliminates the large battery bank and the associated “Prohibitive Cost” and poor “Solar to Electrical Energy Conversion Ratio” of the off-grid system.

    It also does a great job by letting us use that little amount of 600Watts of PV power to partially run our 1.8KiloWatt Load, the rest being “SUPPLEMENTED” by the Grid. As the Sun moves across the sky and more PV power is generated, the lesser utilization of the Grid to power that 1.8KiloWatt Load.

    What I am trying to say is that no matter how much little the power output of Solar Array is, WE CAN BE SURE that it is EFFICIENTLY HARNESSED and USED to the MAXIMUM EXTENT. Since the GRID is an Infinite Voltage Source, the LOAD will never experience a blip or brown-out due to the GRID SYNCING operational topology. You wouldn’t want you LOADS to be blinking/flickering with just a slight change in Solar Irradiation, isn’t it?

    But there is one problem with Grid Synced Inverters, which is:

    As per UL1741 directive, Grid Synced Inverters must shut down within 100millisecs of Grid Failure or disconnection at transformer. This is a safety requirement for maintenance and troubleshooting personnel. This is an important PROTOCOL to follow but if a Grid Synced Inverter stops supplying power to your Loads when Grid fails or is stopped, it wouldn’t be a great topology to use, isn’t it? So we have to find a workaround (which is what I’ve planned and have a decent idea in my mind) to be able to follow the PROTOCOL as well as keep the Loads powered.

    And last but not the least, as Mathias explained way back in his article, it would be great to have a Grid Tied (Synchronized) Inverter with “BATTERY BACKUP” to make it the most suitable, efficient and cost-effective solar power system.

    regards,
    Sudheer

    sudheersrivastav@rediffmail.com
    sudheersrivastav.s@gmail.com

    • Tim says

      Hi Sudheer,

      I am currently working for a University in Australia on a hybrid systems that will intergrate PV panels, batteries and the grid. Im very interested in this idea of Grid Synchronized Inverter that you mentioned.

      However I was just wondering what happens to any excess electricity that might be generated during the day and not used i.e does the excess energy go back to the grid or would it simply go back into a battery bank or not be used all?

      I think this is a fantastic idea if it can be made to work if the grid fails and power is lost. If a battery backup can be implemented for these times then I think the idea is very plausable.

      • Sudheer says

        Hi Tim,
        When the load consumption is less than energy production, it will always be fed back to the Grid for net metering and battery bank will also be kept charged. Otherwise the daytime working couples and their school going kids won’t be happy with my design, isn’t it? There will never be a time when the panels are producing power and are left idle. The only way this can happen is when the consumer is on a long vacation and the grid too has failed for a long stretch of time…..both of these happening TOGETHER is an unlikely event.

        regards,
        Sudheer

        sudheersrivastav@rediffmail.com
        sudheersrivastav.s@gmail.com

        • says

          Hi Sudheer and Tim,

          I’m trying to find this kind of system for my relatives in India. It’s highly weird that it wouldn’t exist “off the shelf”. However, I have some questions for you:

          Sudheer. What you just explained as “an unlikely event” will happen. That is, a sunny day with an electric blackout (and full batteries). Again – where would the energy be placed? Can solar panels simply be switched off the loop (will they heat up or break)?

          I’m from the digital electricity background. It’s remarkable surfing a day does not give answers to these questions.

          Another issue. We visited the local electric utility today (Southern India) and they had not ever been asked about feeding electricity back to the grid. We need a system without the grid back-feeding, at least for starters.

          Third, where is the system getting / maintaining its sync during blackouts? How does it re-sync once power comes back in.

          I think, for our use, we could simply drop grid electricity to DC, to charge the batteries when their level is getting too low (and when there’s not enough PV to charge). Has anyone got such a system going? This would completely avoid the grid syncing problem and the safety protocol issues.

          To reach me -> twitter @bmdesignhki

          • Sudheer Srivastav says

            Hi Asko,

            If this thing already existed, could be bought off-the-shelf and had the exact nice features I have been screaming about all along, I would be the dumbest person ever.

            “You seem to be the first person within our SOLAR SYSTEM, starting to realize what I said about its non-availability is true”

            The “Unlikely Event” which I wrote about, which you say will happen is still an Unlikely Event!

            The Grid supply doesn’t blackout 10 days at a stretch unless we are being attacked by ET’s and POTUS (President of the US) isn’t already having a retaliation plan stored somewhere in Area 52 or wherever it is.
            Solar panels (which we are still not able to afford) are having a conversion efficiency of at the most 21 %( Chinese solar panels). If you tell me that 40% efficient panels exist as per NASA’s SpectroLAB, I can tell you its obvious that its only for NASA and its satellites and not for people like you and me.

            People are forced to use those obsolete/old lead acid batteries which are like S#it bricks in terms of performance, longevity, energy conversion ratio though they are presently the only AVAILABLE ones with high energy density and power density BUT not as GREAT as Lithium Iron batteries.

            “Why we won’t have Lithium Iron batteries when they are so superior and do the near perfect job for us?” Google the Internet and see how many Lithium battery patent wars are going on! Also see how much its development is suppressed to maintain the lead acid battery industry.

            And last but not the least there’s GENERAL SUPRESSION. Anything which doesn’t promote oil and gas usage is suppressed and put to an end in numerous ways. Now I don’t need to offer sermons to people on why and what for this is happening. Google and find out if you already don’t know which I think is a very “UNLIKELY EVENT”….hahaha

            So as I already wrote in the blog the panels being idle is nearly impossible unless a grid blackout occurs for a continuous stretch of days and also the residents are on a long vacation and both of these happening TOGETHER is a very UNLIKELY EVENT.

            Even if the residents are on a vacation and batteries get fully charged, the output of the grid-tied Inverter is continuously fed to the GRID as long its synchronized with it. So you get KWH credited into your account via NETMETERING which means your electric bill is depreciating faster while you’re on vacation due to very low consumption. Finally if power output from solar array is not being consumed, the panels will not get damaged…they are just in an idle load condition. The panels are designed to withstand high temperature conditions for couple of hours each day, for a good number of years of reasonable output/operation.

            India is a place where technology is implemented just before it got outdated elsewhere! So no surprise to me that they have never been asked about netmetering. Without grid feedback you will need a huge battery bank which is nothing but an off-grid system with revert-to-grid function for switching back to grid after juice in battery bank is over! Once gain this is extremely expensive due to huge battery bank….all this I already explained clearly in my previous posts.

            During a planned grid shutdown or a grid blackout…..the grid tied/synced inverter just STOPS! End-of-Story.

            REASON 1: If troubleshooting personnel shutdown the grid supply to you locality and your GT Inverter doesn’t stop/isolate itself from Grid line, that lineman working up there will get electrocuted due to feedback of power from your Inverter! After this you will be prosecuted as per the law. Power Companies take this very seriously!

            REASON 2: Your neighbors and you are connected in PARALLEL to the same street/utility transformer. So if your GT Inverter doesn’t stop/isolate itself, it will be OVERLOADED because neighbors will be drawing hell lot of power from it. If this is left unchecked, the GT Inverter will blow! How can it support the entire neighborhood? Hence the need for it to STOP immediately till Grid is restored.

            REASON 3: Currently available GT Inverters don’t have an option for battery backup for running the appliances in your home during Grid shutdown/failure. THIS HAS NOT BEEN IMPLEMENTED YET. This was what I planned to do and also add much more improvised functionality.

            So listen to this:

            Let’s say your home load is 800 watts and you have a solar array of 1200watts. Now the array will not continuously generate the needed 800Watts every second of the day….it fluctuates and also goes from a minimum to a maximum to a minimum. If suppose your load demand was 700 watts and the panels were only producing 500watts, what will happen? If its simple bulbs or ceiling fans, they will go dim or slowly rotate….below a particular voltage the Solar Inverter will stop working…but what about electronic appliances such as CD player, TV etc and power hungry air conditioners and refrigerators? These devices with compressors and quite many electronics will brown-out due to low voltage and get DESTROYED….yes you heard me right….low voltage can DESTROY too….

            This is where either a battery bank or a Grid Tie/Synchronization comes in handy….to continuously make the fluctuating output of the solar array SMOOTH & STEADY for error free operation of any type of electrical AC/DC LOADS. This I clearly explained in my previous posts.

            During Grid shutdown/blackouts, nothing works so nothing to sync with. Upon restoration of Grid, the GT Inverter is designed to detect and re-sync automatically.

            The idea to drop Grid AC to DC and charge battery bank when it gets too low when PV is not enough is to be used very rarely or only in case of emergencies as I mentioned in my previous posts. Using Grid power to charge batteries even once in a while is counterproductive on your initial intention to become less dependent on Grid and batteries are not so efficient. It’s obvious that quite more amount of power is needed for recharging than that obtained from useful discharging of batteries…..so it will once again raise your electric bill and you won’t be happy!
            So with current implementations available in the market, the grid syncing and safety protocol are unavoidable.

            regards,
            Sudheer

            sudheersrivastav@rediffmail.com
            (I do not use twitter but will email or reply in this blog)

  17. indika illeperuma says

    Hi,
    backgroud….
    I have a project where the current is only needed during the time the sun is bright to produce enought power to facililate the need (so i dont need to charge batteries). There is no grid power available in the area or if i need to get grid support its going to sooo expensive.
    For my understanding the off grid converters are not that efficient as the grid ties. (or the ones which i can afford). Also the new trend is grid ties and such converters are easy access for me. The grid tie converters need the power source to be present to start work.

    my questions is as follows….

    Is it possible to get a low watt (50 – 100W) off grid converter and link with few grid tie(1000W x 5) inverters together?

    The grid ties would detect the output of the off grid and tigger to create the final out put i need.

    I know that grid ties can be combined together. Are the off girds have the same possibility..

    can my idea be practical??? please help

  18. Ahmad says

    I have been researching an off grid system that is capable of feeding AC directly from the inverter and at the same time be able to charge the battery bank. i,e direct AC voltage day time and use battery bank night time. (plus a diesel generator back up )with this system i am totally independent.

  19. Ahmad says

    Xantrax has hybrid inverters, capable of inverting and charging the battery bank, i wil encourage some folks to review it

    • Mathias says

      We`re changing the design because the old one was too inefficient. Should be finished in a few weeks. Will look into the email feature that you are asking for Sudheer.

      Thanks!

  20. says

    Hi all,
    I have a question to ask regarding connecting load to my solar system. if I connect my DC to AC inverter directly to my Mppt charge controller, will it regulate load current also as it regulates current from PV array.

    what I understand is, if I do so, my charge controller (combined with inverter) may act as “solar hybrid inverter”.
    i mean when solar energy is available inverter will take input directly from PV array instead of using batteries and extra energy will be stored in batteries by charge controller.

  21. mihir pradhan says

    Hi guys,

    What will you call the Astra Home series of Domestic Solar Power System launched in India by Borg Energy ? A hybrid one without Net metering / feeding back power to grid ?

  22. Razor says

    Its a great flow of ideas that I see over here.
    I am very much impressed by the idea of Mr. Sudheer Srivastava ,He gave such an insight into the PV system.
    So Do you know about Dispower that was started early in 2002(spare me if I am wrong about the date).As we all know hybrid system have been coming into prototypes since a long time.One thing we always have been worried about is the backup power.As installing a diesel generator doesn’t help the cause of attaining a carbon free environment and battery backs come up with the host of problems like high installation cost/maintenance cost and the need for changing the battery.
    What about integrating all the solar panels in a locality to form a macro-mini grid which is connected to the main grid.In this system we will only keep an emergency battery system.And when during the day time as the production of power would be greater in the daytime,we could use alternate storage methods like hydrogen conversion or methane conversion to use the spare power generated to help us become nearly self sufficient.I am writing a business plan regarding that and thinking of implementing that in prototype in a small village in India afterwards.I an electrical engineer myself and would like to hear insights from people who have a knowledge in the field to give me deeper insights into the subject..

    • says

      Razor, this sounds like a very plausible thing to do in rural India. One might not even need metering in a small village. However, consider that the panels can just as well be placed jointly somewhere, instead of distributed at each home. The wiring will be the same. Maintenance will be easier.

      Maybe… you want also to consider a wholly DC system?

      Note: I’m not a power electronics professional. This is at the edge of my knowledge. :)

      • Sudheer Srivastav says

        (***What I am doing here by answering all these questions is to eliminate the impossible/impractical scenarios and thereby STREAMLINE & SPEEDUP the thought process of people into a think-tank which will hopefully achieve the best possible solution for our common quest ASAP. I do not expect anyone to take the critique in any unintended manner***)

        “Why a DC system is not feasible”

        Low voltage DC power as in solar arrays can be distributed without loss for only a FEW FEET. Medium and Long Distance DC transmission at low voltages is inefficient. The fool called T.A Edison tried to impose this useless DC system on us but the Genius Nikola Tesla invented the Polyphase AC Generation and Transmission System and gave us the World we are so conveniently living in today.

        High Voltage DC transmission is an exception and also very lethal! It is used for Electric Locomotives and certain long distance power transmission. Such high voltage DC lines cannot be used for residential distribution as its highly lethal and can’t be simply transformed to required voltage like AC.

        And finally, most of the appliances in homes whether in villages or urban areas are designed to operate on AC not DC. All our present day electrical transmission and utilization infrastructure is compatible only with AC and I guess there is nothing wrong with it being so.

        regards,
        Sudheer

        sudheersrivastav@rediffmail.com

    • Sudheer Srivastav says

      Dear Razor,

      My reply maybe razor sharp and criticizing but try to understand things before you get hot reading it.

      Happy that you’re impressed by my ideas but there is no one solar power equipment whether Dispower or Borg Energy or whatever which works exactly with the features I mention which we people need for having ANY interest at all in solar power harnessing.

      Also I am happy that you understand the uselessness of diesel generator as it causes more usage of fossil fuel, pollution and an obvious high expense. Likewise you excellently wrote that large off-grid battery banks also are not the solution. Keep it up!

      What I don’t suppose will work is integrating solar panels for community based operation. Let’s say Mr.X has 1000 watts of panels, Mr.Y has 2000Watts and Mr.Z the richest has 5000Watts. So according to you if we form an Integration of a nice gooey 8000Watts, how will the output be distributed? Mr.X has shared only 1000Watts of panels and say he consumes 4000Watts, how will it be ensured that he’s billed for 4000Watts and not just for 1000Watts? A separate Grid and EnergyMetering/Billing infrastructure should be put in place to do this macro mini grid project which in villages or cities is astronomically expensive and counterproductive.

      You may promptly say that a solar power plant will be possible and it can be connected to a nearby National Grid: Before you say so please Google & lookup what is the minimum power range(couple of MegaWatts) and how extremely expensive and useless it is to setup solar power plants connected to the National Grid for the purpose of villages or even cities/urban areas. People have ventured into this and incurred heavy losses and sold equipment to scrap for loan recovery! Not all states or governments have a damn good solar initiative. Exceptions are a few places like Gujarat.

      What is with the spare power generated daytime and the Hydrogen and Methane Conversion? What exactly are these? Please elaborate. If the hydrogen stuff is water electrolysis then please check how much electrical energy is needed to split water and not to mention how will you obtain water pure to a great extent as electrolyzing tap water is not practical due to electrode corrosion, high amperage required and low yield…also check how much energy you will get back by burning that hydrogen. Will the COP atleast reach 80%? Even Solar thermal Splitting of Water is not yet feasible or will ever be. As for methane conversion I haven’t understood what you meant by it as you’re yet to explain but one thing I can straightaway tell you…..

      “The more number of steps in energy conversion, the lower and lower the yield of useful energy, and more expensive the entire infrastructure will be”……we need something which is compact and affordable by atleast middle class families.

      From the day I started posting in this blog, I have talked about nothing but direct energy conversion systems and least possible steps in harnessing/converting/storing/using electrical energy.

      All that I say is applicable from a SMALL VILLAGE to a BIG CONTINENT. By telling you all this I am saving your time and resources so that you do not venture into the methods which will not YIELD the desired OUTPUT but concentrate upon and rethink much better energy harnessing methods/strategies.

      regards,
      Sudheer

      sudheersrivastav@rediffmail.com

  23. vconkey says

    Thank you for this info it was very helpful. I have one question.

    1. If I get a grid-tied system and the grid stops working, does my system still provide my household with electrical power and for how long?

    Thank you.

    • says

      As long as your PV and batteries last.

      This is why we’re planning for a 24h stand-alone system, in other words batteries should take one from the evening onto following morning. Very cloudy days are for the grid (but there would be enough batteries in this scenario to last over grid outages on those days, as well).

      Maybe I’m just describing why there are so many variations of the ways people tie these things together. Because grid reliability and weather differ vastly by geography. Should have subsections for each “solar climate”. :)

    • Sudheer Srivastav says

      Hi vconkey,

      The name seems catchy! Ok first of all there is NO BATTERY BANK involved in a Grid-Tied system. Here the Grid acts as the (virtual) Battery Bank.

      So when the Grid is stopped or fails…..you have no power at all! Even though your panels can output power, the GTI is restricted from working and will not supply even a single watt of power until Grid comes back and it resynchronizes.

      Solar Arrays at the best are a SECONDARY SOURCE of electricity who’s OUTPUT FLUCTUATES with even the SLIGHTEST CHANGE of incoming SOLAR IRRADIATION. On the other hand battery banks and Grid are much more reliable PRIMARY SOURCES who’s output will not fluctuate as much.

      If you don’t have a huge battery bank or the grid tie/synced operation, then the Solar Array output will fluctuate and none of your appliances will ever work PROPERLY.

      Therefore a Grid Tied Inverter STOPS as soon as the Grid stops even though panels are outputting DC power. Grid tie/synced Inverters with Battery Backup have not yet been implemented.

      For a simple explanation read my reply to Mr. Asko Kauppi and further read all my posts to get a comprehensive understanding of the solar power stuff, the pros and cons of being grid-tied, netmetering etc.

      regards,
      Sudheer

      sudheersrivastav@rediffmail.com

  24. says

    Guys The SMA 5000tl is the most advanced grid tied inverter out. It can give 1500w of power when the grid goes down as long as the sun is shining. I tried to get my installers to change out my solar edge inverters, and use them instead,but they are giving me a hard time. This inverter was made in Germany and came to the usa market 6 months ago

  25. Sudheer Srivastav says

    Dear Readers,
    i got an email from Mr. Asko Kauppi which reads as follows:

    (I’ve hashed out his email id with due respect to his privacy)
    From:
    Asko Kauppi | Add to Address book |This is spam

    To: sudheersrivastav@rediffmail.com
    Subject: Sudheer, why do you SHOUT? It’s not nice for us READERS.

    Date: Thu, 03 Oct 2013 20:18:09 IST
    —————————————————————————————————————-

    My reply to him:

    Hi,
    you got me all wrong. Capital letters are stressed words for short reading and are not symbolizing shouting. If everything is written capitalized then its shouting…hope you understand. There is no MS-Word like features in the blog to stress some words and hence have to use capitalization.

    I have been using capitalization before and no one ever said i shouted. In fact you can see few comments that the detailed explanation i have given is good and READERS are impressed.

    Non-technical readers will not peruse the entire comment and i keep getting emails repeatedly asking the same questions again and again and so that they can read in a short summarized fashion i capitalize certain words so that they will quickly understand technical stuff.

    Also i do verify every fact before posting it up there. So that is as polite and responsible as one can be.

    Don’t take me wrong friend.

    regards,
    Sudheer

    =====================================
    I hope other READERS understand the use of capitalization here and do not feel like i am shouting on them.

  26. ding camara says

    Hi Sudheer,

    i am from the Philippines.if you are familiar with “SAMIL POWERS GTI”, can you give me any comments on its performance?

    best regards,
    ding

  27. Bob says

    In most parts of the US feeding power back to the grid (excess production) and you will be paid .13 cents per kilowatt hour . That was with a 5.7 kwh array. At that time (2009) we were allowed up to 10kwh per residence. Since that time we have found that we conserve our electrical use and often times get REC credits back from our power company to the tune of $100.00-$140.00 US dollars per month. As of Oct 2013 the power company will not allow us to add additional panels as we are acting as our own utility company. We also get approx 310 days of full sunshine per year. In comparison to India or S Africa it may seem greedy on my part, but that is our capitalist society. Question is, since I am grid tied, can I disconnect certain appliances (I.e. refrigerator, well pump, and what ever I desire and hook them up to batteries (isolate them from the grid in my electrical panel, with a new panel) new solar panels/ batteries as a way of getting around my limit with my utility company and not break their rules of increasing my solar array that I have contracted them with. Some ideas may work here, but most appear just happy to get power and unhappy to give it back to the grid for free? Replies appreciated. Thanks

  28. Shadi says

    Dear All,

    Thank you all for these very useful information…the topic is new and interesting!
    Mr. Sudheer is Hybrid king I call him :)
    I wonder did you or any other company achieve prototype of this hybrid system until now?
    I’m very interested to buy this in my region!
    many thaks again and keep the hard work

    Kind regards,
    Shadi

  29. Ralph De Vito says

    Why can’t we have a solar system that is not tied to the grid whereby the power from the panels goes to the AC inverter and then directly to the house panel.Why does everyone say we need batteries. A AC generator goes directly to the house panel. What is the difference? Once we go the AC inverter this should be suitable to go to the house panel? If not why? Is the AC from the inverter different than from the generator or the grid?
    Also can the power from an AC windmill go directly to the house panel?

    Thanks,

    Ralph De Vito

    Ralph DeVito

  30. Ibrahim says

    Are there Charge controllers that can use utility grid power as a backup? I have to design a PV system for a DC load, and I will be using DC rectified grid power as backup. So do I still need to a battery bank in my system, and will it be ok if I connect the DC rectified grid power to the charge controller same as the PV power, and use an automatic changeover switch to change when PV output is low?

  31. Maricel C. Dalde says

    Good Day!

    Can I ask if we can combine the off-grid and on-grid system? We have plan to supply the power from solar panel while supplying the power from grid to the load. But when there is no power from the grid, we can still used the solar through an stand-alone inverter but we will used the automatic transfer switch and identify the load that will be supplying for the 5kw system. It is possible? please reply. Thank you so much!

    Maricel

  32. wahid raafat says

    i am new to renewable Energy , i fully support your idea but . i have another idea don’t know if exists as a product or as inverter feature , the idea is a hybrid system without batteries , if we can have an inellegent device (possible the inverter ) that can detect the load and decide if enought solar power then use it to supply load , if not enough then combine it with grid . if we have excess solar pass it to the grid . we will save the high cost or batteries and it’s maintenance/replacement costs . what do you think

  33. Sohail says

    Hi this is sohel nd i’m searching for an solar inverter that will back up my refrigerator nd ac for maximum hrd of the day can u suggest me an inverter with such facilities.

  34. Asma says

    hi Mathias, I’m going to ask something very silly: what is the difference between solar PV inverter and hybrid inverter. I’ve read the Wikipedia pages but can’t understand which is better. you see I want to install a solar system of a 1000 watts….one company I talked to said that they provide hybrid inverters only for systems of 3kW or above below that it’s solar PV inverters…why??.. thanks

  35. Asma says

    Hi Mathias, I want to install a 1000 watt solar system…. a company I talked to says they offer solar PV inverters for systems below 3kW and for above hybrid inverters…which is better and what’s the difference? thanks

  36. Anupam says

    This one thread has given me complete know how of hybrid solar systems.

    I just also spoke to Borge people, seems it can meet my needs (without net metering) which is ok

    @ Sudheer, you have mentioned that features in your to-be system is much advanced, can you help me in layman language on them

    As an FYI, I am not from this industry and have read as an interested end user, hoping that I may find a solution cheaper than buying from the grid

  37. Romeo Asibal says

    Yes, I agree with you..Thanks to Mathias and thank you all for your contributions. I am into off grid solar pv system here in this part of the Philippines while waiting for grid to arrive in 5 to 6 months time. What I need is a grid-tie ready inverter that uses batteries for the time being.

  38. Amarikwa Moses says

    Mathias thanks for the post, please i need more about the others like inverter/ charger backup system, stand-alone system, etc.

    Best Regards,

    Amarikwa Moses.

  39. Skyx says

    Hi there,

    I have been using my Grid-Tied systems over the last 2 month.
    I have 3 140 Watt solar panels. Feeding back to the Grid and I’ve notice that my electric bill has gone up. I just wanted to know what I’m doing wrong. Or should I move on to the “hybrid solar systems”. I did this to save money, but it’s costing me more. I live in GA, and seem like the smart net metering is not helping at all. Any help or idea would be much appreciated.

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