String inverters for grid-tie

Discussion in 'Solar Power' started by Derrick Grimmer, May 18, 2015.

  1. Glenn from Windy Nation suggested that I post my question in their forum:
    I am building an emergency PV/battery/inverter system using your 12 V modules. The system is demountable & storable in a compact fashion in our garage, to be set up and used in catastrophic conditions when fuel may be become unavailable for our generators.

    The system when completed will use 20 of your 100W 12V modules, wired in parallel.

    However, I was thinking, perhaps I should explore also the possibility of hooking them up to the grid, using a string inverter: putting the modules to work rather than let them sit in storage.

    If the 20 100W 12V modules would be wired in series, this 2 kW system would be a 240 VDC, 8.33 A output system.

    Can this 240VDC output be fed into a string inverter, whose output could then be connected to the grid via, say, a 30 VAC dryer plug output? (I have such a cable made up for a 7 kW gasoline generator, to energize the house circuit -- mains & large load breakers off -- to keep well pump, a fridge & some lights on. It uses a 240 VAC 30A twist lock plug from the generator to a 30A dryer plug on the wall, with a breaker. Works slick).

    So questions:

    * Can the modules/cabling be used without damage in such a series connected fashion, where there is a 240 VDC voltage drop? (I assume the frames would need to be ground wired together to avoid potential shock at the frames).

    *Can you recommend a suitable grid-coupling string inverter to do what I want? (I don't see a string inverter in your product line). For safety, the modules should immediately auto disconnect from the grid if the utility power goes down, i.e., no islanding possible.

    * Has in fact anyone done what I propose with your 12V modules?

    I look forward to your reply.



    Glenn's positive response:

    Hello Derrick and thanks for your email.

    This does sound interesting and we must agree that it would be a waste to not have this set-up generating power all the time.

    Each panel will generate a voltage around 17-18VDC so with twenty in series you would have approx 350VDC.

    We do not offer any Grid Tie Inverters or String inverters but there are many applications in use.

    Unfortunately we cannot offer any wiring instructions as it pertains to the grid as this needs to be addressed by a licensed electrician who is familiar with all the local regulations.

    One resource of information for you may be our forum:

    There are hundreds of active members who may have similar experiences and can provide additional guidance.

    Hope this helps


    I await responses/suggestions.

    I should further point out that the ground-mount module foldable-supports, the batteries, and the 4 kW 12V 230VAC split-phase inverter are already acquired & wired, intended mainly for emergency well-pump use.

    I also have an existing 19.5 kW roof-mount grid-tied PV system. The new ground mount system turned out to be about 1/3 the cost of tying in existing roof module rows into an AC-coupled inverters. All the fuss about Tesla's Li-ion batteries to the contrary, the batteries are the least of it. It's a long story.

    At this stage in my life it's all just an experiment. A 2kW 'guerilla solar' plug in the wall solar system seemed like a fun thing, provided the safety is there for the utility. You will find no better & inexpensive battery than the utility -- when it's up.



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