Need help with grid backup system
Hi ALL. I’ve been struggling with designing a PV system, and hope that someone here can offer some advice that might point me in the right direction.
I’m looking to have a 3 – 4K system. I currently have (10) Trina 320 W modules.
System operating similar to Xanterx “utility backup / Outback “minigrid “ mode. Draw power from the grid to supplement pv, with NO SELLBACK.
I need the main charge controller & inverter to be
dependable & fairly flexible
I would like to have a small battery bank – mostly to help with appliance “start” surges.
CHARGE CONTROLLERS: MPPT Charge controllers(s) to handle modules.
24V battery. The modules. will be 50 – 60 away so copper is a consideration. I may add (possibly different) modules later, or need to split them unbalanced strings, so the ability to handle unbalanced loads is a BIG plus.
Easily varied charge rates is a must.
INVERTERS: Ability to do “utility backup – NO SELL BACK IS A MUST.
Dependable Pure sine wave is needed. Might add a “Chinese
wonder” later for noncritical loads. I can easily separate house circuits.
It seems like Optimizers used with a higher voltage inverter ( Fronius ?) could make setting up the module strings easier, and reduce wiring costs, but would that work in the “mini grid” mode. What does that do to the battery bank – charging and inverter dc inputs of 300+V from the modules and 24V from the batteries.
BATTERIES: To get things started I will probably use a couple 12V deep cycle batteries that I have. Want to switch to another type later – possibly LIPo4.
Min. record daytime temp here is about 0 deg. F.
Inverter(s) brand / model recommendations please. Fronius seems to make some interesting units – I wonder about service as they are non-us made.
It seems the more I dig into this, the deeper in the hole I get.
BTW I don’t expect
any savings from this system to pay for itself. It’s gust something I really
want to do. And of course keeping costs down is a must.
Thanks in advance.