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Why photovoltaic consumes from network despite the fact that battery is full?
Posted: Thu Jun 08, 2023 1:36 pm
by ondrejgrim
Dear all,
my photovoltaic consumes approx. 3 kWh from network every day even if my production / battery can fully cover consumption of my house. Do you know any reason of this behavior? Please note that Export of the electricity to network is currently disabled. Could it be the reason? But isn't 3 kW per day too much if you take into account that consumption of my house is < 3 MWh per year?
Re: Why photovoltaic consumes from network despite the fact that battery is full?
Posted: Sat Jun 10, 2023 11:29 am
by graham
If I work that out right, 3 kWh over 24hrs is an average draw of 0.125 kW.
Looking at the power values relating to the battery and displayed by the app for my system, the output power is different from charge power or discharge power by a value that I assume is the power consumption of the inverter/charger itself and any losses to inefficiencies in it.
When the battery is at 100% and the charge power and discharge power are 0 W, the output power is a fairly consistent 20W less than 0. When the battery is charging, output power plus charge power is about -90 to -100W, and when discharging, there's about 90 to 100W difference between output power and discharge power. There could be some measurement error in them, but the inverter must take some power from somewhere, even when the battery is full.
So while your value of 125W seems a bit much, in comparison with my system, if it's just for when the battery is 100% charged; it might be less unreasonable, if still a bit high, if it's an average including charge and discharge periods.
So I think it's worth you having a look at the output, charge, and discharge power values for what the inverter/charger appears to be consuming/loosing when the battery is charging, discharging, and fully charged.
Graham
Re: Why photovoltaic consumes from network despite the fact that battery is full?
Posted: Tue Jun 13, 2023 9:09 am
by ondrejgrim
Thank you for response. MAYBE I got it - I have realized that if I turn off main circuit breaker, my power plant starts charging house from battery, BUT it doesn't produce new electricity. I have also realized that consumption is going up - it was about 1 - 2 kW in Winter and is about 3 - 4 kW now, when production grows due to more sunny days (guess that inverter's consumption grows in dependency of production). Could it be that assembly is wrong and inverter is directly consuming electricity from network instead of being charged by power plant itself?
Ondrej