January 19, 20242 yr Hello, today a beautiful sunny day, and new problems appear! When the AC load is low, and the PV power is high, the battery charge fluctuates. We see it on the graph I "play" with the water heater, when it is on, the pv power is stable, and as soon as I turn off the water heater the battery current drops then rises to 150A, then falls again then rises again... The problem is visible on mppt 2 the voltage drops to 150v. I just changed from 3p8s + 3p8s to 4p8s + 2p10s. I don't know if the problem arose before because it's been a long time since there was a strong sun Or maybe in 10s the power derating is already effective? I know that if I exceed 360 volts the charge no longer exceeds 90 amps Can too little AC consumption pose a problem? last summer the problem did not arise I always consumed more because of the pool pump which worked all day thanks for any help
January 19, 20242 yr 2 hours ago, Br999 said: Hello, today a beautiful sunny day, and new problems appear! When the AC load is low, and the PV power is high, the battery charge fluctuates. We see it on the graph I "play" with the water heater, when it is on, the pv power is stable, and as soon as I turn off the water heater the battery current drops then rises to 150A, then falls again then rises again... The problem is visible on mppt 2 the voltage drops to 150v. I just changed from 3p8s + 3p8s to 4p8s + 2p10s. I don't know if the problem arose before because it's been a long time since there was a strong sun Or maybe in 10s the power derating is already effective? I know that if I exceed 360 volts the charge no longer exceeds 90 amps Can too little AC consumption pose a problem? last summer the problem did not arise I always consumed more because of the pool pump which worked all day thanks for any help 10S I would guess is a risky connection to have.
January 19, 20242 yr Author the mppt goes up to 450v, and in 10s I do not exceed 375v I think the safety margin is sufficient, right?
January 20, 20242 yr 9 hours ago, Br999 said: the mppt goes up to 450v, and in 10s I do not exceed 375v I think the safety margin is sufficient, right? Yes that is correct. I in error used your reference to 360V / 90A you mentioned. Yes with a 450V MPPT you are well clear of the maximum.
January 20, 20242 yr Author yes but I find that they were wide with the derating, for a 500v voc and 450v mppt inverter, from 360v PV the battery charge goes from 150 to 90a! 60%! It's a bit of an abuse because it's not written anywhere in the manual!
January 22, 20242 yr Author Hello, has anyone had this problem or anything similar to it? when the battery charge reaches its maximum and the AC load is close to zero, intabilities appear on an mppt, the one where the voltage is the highest? I tried to invert the inputs, the problem is the same, the input where the voltage is the highest fluctuates arrived at 150A battery charge when I have time ans sun I will try in 8s on both mppt but there is work to change all that. no idea ? thank you
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