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Anil Ghatikar avatar image
Anil Ghatikar asked

Cascading two ESS systems?

Can I consider adding a small 2 KVA single phase ESS ( 1 KW PV) to ACout 2 of a large 15 KVA 3 Phase ESS system( 11 KWp PV) . Doing this can potentially allow me to add some critical loads to AC OuT 2 but still maintain loading capacity of a 15 KVA ( limited right now by the size of battery 10 KWH BYD pro)

The 2 KVA single phase will run its own 10 KWH lithium battery ( from a different manufacturer)


Or is it better to just run the system in Ignore AC mode and forgo the efficiency gains as the 1 KWp panels will supply a peak 250 Watt load




ESSBYD
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2 Answers
Paul B avatar image
Paul B answered ·

Give it a go and please advise the out come as others may like to know.

you are doing stuff thats not that common so you may have to just try and see the result.


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Anil Ghatikar avatar image
Anil Ghatikar answered ·

I tried and no issues observed in 3 hours of operation . Reset the system back to offgrid till I find more time on weekend

Of course the export to grid was not allowed so ESS only managed to feed the load and then throttled back the PV Also the grid was present at the time


I am using 1.5 KWp 150/45 bluesolar with single phaseMulti 800/48/9 with 10 KWh Lifepo4 battery with cheap chinese BMS connected to 5 x 3 KVA Quatro with 10KWp solar ( Smartsolat and fronius with 10 KW PRO BYD


Things yet to try and frankly too afraid to risk unless some clear examples or guidelines available


1. Disconnect the grid and see the behavious of Downstream multi - essentailly will LOM consider impedance of Quatro as grid or go into overload and disconnect


2. Allow export of the power from multi - with grid - I see no major issues as the house load is much higher than ~600 watt the system can feedback

3. Allow export of power with no grid and no load on Quatro to check safety interlocks

a. PV inverter assiatnt in quatro to check if multi disconnects on 53 HZ ( not happy with solution)

b. extenal conactor on input of Multi to disconnect from quatro when SOC of main abttery is higher than 95 % ( Reliable and tested with a APS 1000 Watt inverter) but then multi works in island mode most of the time







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