If you know Outback SkyBox inverter settings and you're willing to give feedback... thanks! mike@slowpower.wtf
(Outback (or Outback's parent company) didn't reply to my support requests.)
Late last year, new friends asked me to help them get their hybrid PV + battery system working right. They installed the system themselves (correctly) in the Oakland hills.
It includes a 4.4 kW PV array.
There were two 5.1-kwh white-labeled GSL Energy batteries... they failed / fried because of bad design (GSL Energy honored the warranty), so I replaced with one 16-kwh Discover Helios battery.
The intention is to use as much PV power (directly and thru the battery) as possible. This is a zero-export situation. I've struggled to get this dialed in... the Helios BMS has disconnected / shut off the battery twice, and the system shut off when the grid went down on Christmas Eve (and the site stayed dark after grid power was restored) 😑
My current settings for this SkyBox are here.
On the Grid tab, I'm in Non-export mode.
GridZero Max Threshold inputMy understanding: This is the inverter's maximum-grid-import target. It'll use the battery aggressively (if needed) to keep the maximum grid import below this target.
The accepted input range is 1 kw to 50 kw.
The typical site load is around 0.4 kw. When the load is under 1 kw... will the inverter nonchalantly use grid power?
Or if it still prioritizes using the battery... what's the point of this input?
On the Battery tab, I currently have minimum state of charge (SoC) at 30% and maximum state of charge at 100%. And I have low-battery cut-out (LBCO) voltage (conservatively) at 51 volts and absorb voltage at 55.9.
My understanding is that the SkyBox will stop discharging once either low SoC or low voltage is hit (whichever happens first).
Once that happens, the SkyBox will charge the battery at the maximum charge rate (using both grid power and PV power) until it hits the maximum SoC or the absorb voltage + absorption time (again, whichever happens first).
...Then it will prioritize battery discharge over grid import until the floor is hit again (unless PV charging keeps it above the floor).
Do I have that right?
If I set the SoC range to: 0% to 100%...
Then, in reality, only the (narrower) voltage range will apply right?
(The SkyBox doesn't support closed-loop communication, and I'd rather rely on its voltage reading than its coulomb-counting algorithm... I hear that the latter can drift from reality over time without the absorption reset.)
To maximize PV power use while ensuring that the battery BMS doesn't disconnect the battery... should I change anything?
Thanks for any support — please send feedback to: mike@slowpower.wtf
I might add it here (anonymized).