June 22, 20215 yr Hi all Hope someone can help me. We've got the following installed : 2 x TheSunPays Axpert 4kw/5ka Clone units (Axpert MKS clone, low voltage) 3 x TheSunPays 48v 100Ah LiFePO4 batteries 9 x Canadian Solar 360w poly panels (3S3P) 4 x JA Solar 535w Mono panels (2S2P) The problem is with the JA Solar 535w panels that is connected to the Slave inverter. 2 panels are flat mounted on IBR, 2 panels are mounted on tiled roof at a 25ish degree tilt north facing. The panels are brand new and we commissioned them over the weekend, today was the first test run. Voltage readout at the DC Isolator is 90v At peak sun today we only got 500w out of the 4 JA panels while the 9 Canadian Solar panels hit 2.7kw. The panels were not in shade. Charge limit on the slave inverter is set at 60A, batteries were at 35% and load was roughly at 1kw throughout the day. Each series circuit has its own positive and negative running to them, each lead is then fused with 15A fuses (2 x fuses for each series circuit, 1 on positive, 1 on negative). I went to check now, and 2 fuses were blown (no continuity, no resistance, nada). We have 2 theories. 1. The fuses were DoA 2. The panels amperage went too high and caused the fuses to blow. The Data sheet however says the panels Short Circuit current is 13.79A and Maximum Power Current is 12.90. Hence why we used 15A fuses. I would like to hear what forum members think what happened so as to guide is roughly in the correct direction. This was a DIY install. Edited June 22, 20215 yr by Bl4d3
June 23, 20215 yr 3 hours ago, Bl4d3 said: panels Short Circuit current is 13.79A and Maximum Power Current is 12.90. Hence why we used 15A fuses. I think that 15A is too close to the panel output. Try 20A fuses. It would be better to have both strings having a similar mounting arrangement. Otherwise, you risk one string pushing power into the other string.
June 23, 20215 yr Author 3 hours ago, Coulomb said: I think that 15A is too close to the panel output. Try 20A fuses. It would be better to have both strings having a similar mounting arrangement. Otherwise, you risk one string pushing power into the other string. Thanks We will give the 20A fuses a try. Ideally we would have done a similar mounting layout but due to space constraints, we could not. Would adding a diode in line work sufficiently to prevent back feeding?
June 23, 20215 yr Author So it seems we have come to the conclusion of what happened. 2 x 15A fuses were dead on arrival. We replaced the 2 fuses last night and we got the following output : 9 x Canadian Solar 360w Poly - 3.00kw 4 x JA Solar 535w Mono - 1.5kw This was in cloudy conditions when there was a bit of a break in the clouds.
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