nowty wrote: ↑Wed May 24, 2023 2:39 pm
You'd need to build a high voltage battery as the turn on voltage of the inverter is 120V so we are in lethal DC land. Also the impedance of the supply of a battery is significantly lower that a solar string so you risk damaging the inverter. The inverter is expecting the voltage to drop rapidly as current flows but it wont from a battery.
Saying that I have personally done something similar in the past to transfer grid power to an OffGrid system. I used several grid powered PSUs in series to get the DC voltage up to about 130V and connected it to a standard SMA grid tie inverter with a power limit output set on the inverter to stop the power supplies overloading.
Thankfully those days of craziness are over for me, I would not recommend what you are thinking. You could sell on your Solis and replace it with a hybrid model which takes batteries. Then you need to work out how to get the inverter and the powerall to play nicely.
Don't do this at home folks, especially if you don't like bangs and magic smoke.
Thought it seemed a bit too simple in my head! Many thanks!
So more solar into DC storage through hybrid inverter which can be switched to supply house when solar and Powerwall are off??
I have been thinking how to tie in a hybrid inverter and diy battery to work with my Powerwall and was thinking a simple way would be to programme the hybrid inverter to export approx. the base load of the house any excess would be taken up by the Powerwall and any additional load would also be supplied by the Powerwall. Well that was the general idea!
3.87kWp PV
10.24kWp PV SolarEdge system
Tesla Powerwall 2
100 x 47mm Navitron tubes (still being installed!) Now likely to be removed for more PV.
MK2 PV router DHW diverter
Morso 5kW WBS
Vaillant AroTherm 10kW ASHP
Nissan Leaf
Moxi wrote: ↑Wed May 24, 2023 2:49 pm
Whats your solis inverter model number as I know in the manual for some of the solis inverters it says its possible to run the inverter from battery only ?
14Kw Mitsubishi Ecodan ASHP
22 x JA Solar 455W Mono Perc Half Cell Silvers
Solis 8.0Kw 5G Dual MPPT Inverter
13.5Kw Tesla Powerwall
Zappi 2 Charger
iBoost
Yep what Nowty says, unfortunately the Solis inverter you have isnt flexible enough to do what you are after, so as Nowty says either sell your current inverter and buy a hybrid or keep the current inverter (as long as two strings can be configured to give you your 120Vdc starting voltage) and buy a small hybrid inverter which can be used to charge the new batteries you want to buy and supply say 3kW AC to the house when the sun dips, however there is then the issue of getting either the new hybrid inverter or the Powerwall to be subservient to the other.
There are other options but understanding the auto disconnect of the powerwall from the grid during a grid outage would be key to ensuring you don't add something to your set up that could kill a linesman.
