Topic

-1 vote
How do you use Enphase M215s with an off-grid system including a generator?

We're working on a home with a generator on-site to account for frequent grid outages. The customer wants to use Enphase micros, but we're not sure of the implications when the grid goes down. Any way to make this work?

Comments

Martha on June 29, 2012 - 8:17am
Tbone,
Your situation is not exclusively off-grid. You have a grid tied system with a generator - the difference is that grid availability, while possibly unreliable, is the default operating environment for the inverters and residence.

Here are two possibilities in order of cost:

High-tech, high cost: Design and install a separate charge controller / inverter / battery on a protected load center with the Enphase being a circuit of that load center. You may need to sell the generator if it's old fashioned and replace with a large battery bank. The inverter will have to have firmware capable of managing the Enphase inverters. You will also have to plan on a voided warrantee for the Enphase inverters if anything goes wrong. See this article for more background: http://www.civicsolar.com/node/12693

Low-tech, low cost: Between your generator and your utility meter, there is a transfer switch. Connect your Enphase inverters to a small 125A service panel that is positioned between that transfer switch and the meter. Grid will go down, switch will isolate house, generator will come on - and the Enphase will be turned off and blissfully secured by their warrantee until the grid returns.