question

anonymous37389 avatar image
anonymous37389 asked

18% voltage drop / 400 watt / mppt 150/35

Hi,

I have one 410watt solar panel running at 42.3 volt. I meassured it with the multi meter at the mc4 connector directly on the panel.

Now when I connect it to the Victron MPPT 150/35, i only read 33-40Volt in the victron connect app. Avg. 35-36 volt. The panel also doesn’t generate 400watts, but the max i have seen in Greece is 330 watt.

I have around 10 meter of 8 gauge wire through my sailboat, 8.36mm2. Which should be thick enough?

Its a pretty big drop 10-20%…


Any ideas? Thank you


MPPT SmartSolar
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1 Answer
seb71 avatar image
seb71 answered ·

Some comments:

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If it's on a boat, it might not be optimally oriented towards the Sun. So expect some power drop from that.

Also if there is any shade, you will have a power drop because of that.

High panel temperature also causes a power reduction.

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PV panel open circuit voltage is always higher than PV panel voltage when generating power.

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Even if using a 12V battery, the MPPT maximum current to the battery (35A) corresponds with about the maximum power output of your PV panel, so that should not be a limiting factor.

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The AWG8/10mm2 wires are thick enough, if those are between the PV panel and the MPPT.

Between the MPPT and the battery you should have thicker wires - 16mm2/AWG6 (and as short as possible).

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You have to make sure that the generated power has somewhere to go (charging the battery and/or powering some loads).

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