Hi,

I'm trying to figure out the most effective way to run the inverter with a grid + solar + batteries.

But I'm getting strange results as follow:

In SBU with 3kW coming from the panels (and a load of approx 800W) and batteries at anything below 100% the feed from the grid is running at around 5-6A (around 1.3 -1.5kW)

When the batteries reach 100% this drops to around 200mA. As soon as the batteries drop to 99% the grid load returns to 5-6A

I have set charger source priority to Solar only and set the timer setting  (program 100) to only solar.

It seems the grid is providing power to the load even though it shouldn't.

It also appears (when no solar) that the batteries aren't charging or discharging (soc remains the same) but the grid load is around 1kW more than the output load. At this power I would expect a lot of heat generation but no - no heat - where is this 1kW going??

Batteries are Pylontech US3000C

 

What main (U1) firmware are you running? I vaguely recall that there was a fix for some charging issue, perhaps matching the above. But there are so many firmware versions these days.

4 hours ago, Acuario said:

where is this 1kW going??

It's probably 1 kVA, possibly nearly all reactive, e.g. 1 kVAR. The 5 kVA/4 kW models typically transfer about 300 VA of capacitive imaginary power, because of the large C (capacitor) in the LC (inductor-capacitor) filter at the output of the main DC-AC converter. Ideal capacitors don't dissipate any real power. I don't know the figure for the 8 kW models, but you'd imagine it would be roughly proportional, so of the order of 500-600 VA. So that may explain at least half of it. Some of it could be due to self consumption (~50 W for the 5 kVA models), and losses (about 7% of the load for 5 kVA models).

Edited December 25, 20222 yr by Coulomb

U1 is 81.01, this is the round display version.

Thanks for the explanation, it seems odd though that when the batteries reach 100% it drops to only 200mA.

Interestingly the QBMS message then has the Battery stop charge flag set to 1 and the max charge current drops from 150 to 10 - and dropping from 100% to 99% charging current only goes to 80A. I need to check when it goes from 80 to 150.

 46% QBMS:(0 046 0 0 0 532 532 450 0150 0220
100% QBMS:(0 100 0 0 1 532 532 450 0010 0220
 99% QBMS:(0 099 0 0 0 532 532 450 0080 0220

It's a pity there isn't a way to force the battery to stop charging - it must be read via the battery bms but there seems no way to force the condition.

6 hours ago, Acuario said:

it seems odd though that when the batteries reach 100% it drops to only 200mA.

I agree with you there.