Deye hybrid inverter 10kW-12kW: Recharge Battery using Grid (Power/Energy Trading)

silverstone

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May 3, 2022
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I am planning to install 40 extra solar panels on my roof and was looking at the Deye SUN-12K-SG04LP3 inverter with some BMS (still undecided, I think active balancing will be required given the high nominal current) and some DIY EVE 280Ah batteries (48VDC system, so I am looking at 16 cells in series).


I was thinking 4 parallel strings, each protected by a 63A DC breaker, that should give enough power for the full inverter rating and energy to cover for a long time. Alternative could be 125A fuse holder with 22x58mm 80A-100A fuse, but that is a bit more difficult to source for DC application ("certified" DC breaking capability) and much higher power losses (approx 25W-40W per each string, across the 2 poles of the fuse holder put together).



However, I didn't see anything in the manual that could force a "float battery" or "force charge" on-demand. The only option I saw was time/hour defined charge.


Given how here in Europe electricity prices vary a lot between days of the week as well as between time of each day, I'd like to be able to trigger a "force charge" (at a predefined rate, e.g. 200ADC, approx. 10kW) whenever I want, using Home Assistant for instance.


Such "force charge" mode could either be triggered via Software/Console (e.g. Deye USB/RS-232 Interface) or ideally via a Relay (but there is no such relay in the Deye system ...).


Options I am considering:

1. Charge "time/hour" defined charge via USB/RS-232 (if possible). I couldn't find any USB/RS-232 registers and programming guide. Or even better a "enable charge from grid" software toggled "switch".


2. Always set "time/hour" defined charge to e.g. 02 in the morning. If price is too high, disconnect Inverter on Grid Side using an AC contactor (63A rated). If price is OK, leave contactor closed (Grid charge will be performed). Downside is that the charging time is always fixed.


3. Enable 100% of the time battery charge above ANY SOC/Voltage but only through Generator.

Then of course switch AC "Generator" ON using an AC contactor connected to the Grid directly (via MCB Breaker for protection of course) and disconnect Grid AC contactor (to avoid "loop").


4. Contactor on DC side, on one of the PV Strings. The TDK EPCOS HVC 200A/300A is the first that comes to mind at approx. 100 EUR. Basically open PV strings at night and, if desired, close another contactor that will be connected to a AC/DC converter (6-pulse Diode Rectifier for instance even though grid quality would be bad). Deye inverters need minimum 200 VDC in order to work.


5. Add a "battery charger" directly on the 48VDC battery (leaving inverter connected) and switch on/off battery charger via AC contactor. Needs another costly component (approx. 10kW 48V charger ...)


Does anybody here have experience on the USB/RS-232 on the Deye inverters? Is this only for data retrieval (e.g. read MPPT voltage/current/power, AC power production, ...) or can you actually change the inverter settings ?


Thanks a lot for your help :)
 
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