Batteries for whole home.

[Tim Kepler]

I have 175qty 310 watt panels and I want to take my house off grid. I live in PHX Az and have a 2000sf home with one Ac unit. What is the best expandable battery system at a reasonable cost? Also, what inverter is out there that will do both grid tied as well as off grid?

 

[BentleyJ]

Rack mount batteries seem like the most logical. Start with one rack with 5 or 6 slots and one or two batteries. If the floor space is limited for rack type then wall mount but it requires some planning ahead and having adequate wall space.

Inverter will have to be UL 1741 SB compliant, grid interactive. In Arizona I would think the utilities have a list of approved equipment same as California.

 

[740GLE]

How’d you come across 120 PV panels?

 

[Tim Kepler]

How’d you come across 120 PV panels?

They got QAQC’d off a large utility project for scratches to the frame. All panels work great. A few do have scratches to the white backing but they are very small and are not deep and test great. Probably won’t last 30 years but that’s ok

 

[DIYrich]

That's a lot of panels, and with ac you will need a lot of power, especially in AZ.

Go for the sol-ark 15k or eg4 18kpv. They should be able to run your stuff. And are easily expandable.

With 36kw of panels, you will exceed the 19kw of the 15k. 18kpv is similar. Overpaneling is ok. Maybe face some east, and some west so you have more hours of high production.

For off grid, I'm guessing you will need atleast 60kwh of batteries to last 3 rainy days, or whatever you get in AZ. Both inverters can easily expand. The eg4 powerpro is about 15kwh, but weighs 300 pounds. Rack batteries are 5kw each and weigh about 100 pounds. If you have ground floor install 300# is doable. Basement will require help. At a minimum, start with 15kwh, and add as you have funds available.

Whether you use all 36kw of panels is up to you, while on grid. Once you are off grid, you may need all of it to recharge 60+kwh of batteries in one day to last the next 3 days of poor production. If you are maxing put the inverter and need to use the excess production, then you can add a second inverter in parallel. Plan for that, and it will be easy upgrade.