Alex KretzschmarJan 25

This winter storm is making me actually think about installing a whole home backup power source (I know, me and half the US right now).

I already have solar but no battery as my utility company does 1:1 net metering.

Does anyone reading this have any experience in building a grid-tie battery system? Powerwall is an option I guess but I’d like to DIY this thing if I can so I choose when it get charged not an algorithm.

Show threadAlexander SJan 25

@ironicbadger First of all, what type of the inverter do you have?
If it's grid-tie, most likely there are micro inverters under panels generating pure AC and shutting down when they don't sense the grid.
You may need to add a transfer switch that isolates home from the grid and AC battery (like powerwall) that generates base 240v.

Most diy batteries are DC (like recommended EG4) that you connect to a string inverter (takes solar panels in series). This one is much easier.
My friend has installed Sol-ark 15k inverter and thrown in 48v batteries.

Show threadAlex KretzschmarJan 25
@alexgreen the issue my research has highlighted is that my SolarEdge inverter is grid tied as is and thus I cannot use the solar if the grid is down (I knew this but it is still stupid).
Powerwall gateway solves this but I don’t really want to give that fascist money.
Show threadAlexander SJan 25
@ironicbadger understand you. if you can modify the existing setup, you may replace the inverter and use standard cheap 48v batteries.
Or buy another 'offgrid' inverter with DC batteries and use as fat UPS for dedicated circuits or the whole house. Even if the old inverter goes down with the grid, a second one (that stays between house circuits and the grid) will power your house.
Show threadAlex KretzschmarJan 25
@alexgreen with the minor downside i can't use my existing 8kw array to power them in an outage!
I already have the interlock for a generator so some kind of hybrid where I can slam the batteries from the gennie for 1-2 hours and then run the house for 12 hours at a time seems like a great middle ground without breaking the bank. not as swanky as a grid tie battery but not as $ either!
Show threadAlexander S

@ironicbadger yeah, interlock is a good temporary workaround.
I installed it as well. Tiny 1800w generator-inveter may power all critical outlets in my house, but I need to dance around what circuit to turn up :)

There is a big room for efficiency and reliability in the solar world.

Jan 25 at 4:21pmWeb