question

oscarmax avatar image
oscarmax asked

Which wire for PV to Smart Solar 75/15 to Battery?

Please excuse my grammar I have suffered a brain injury

My setup will be 2 x80w mono solar panels with Victron Smart Solar MPPT 75/15 to 12 v battery, this should produce in theory 9 amp maximum.

I have fitted a new Smart Solar 75/15, I going to fit my new Smart Battery Sense, the original factory wiring from my old PWM control to battery is 4 metres long in 2.5mm twin core wiring, based on 9 amp this setup will have a voltage loss of 4.08%.

I have read somewhere that the Smart Solar will automatically compensate for this loss or do I need to change the wiring to 4.5mm.

wiring
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3 Answers
JohnC avatar image
JohnC answered ·

Hi Oscar. Your grammar is fine.

At the nominal 12V, 160W of panel is closer to 13A. Over 4m distance, and both ways, no point mucking about.

Your 75/15 has terminals specced for 6mm2 wire for good reason. That's what I'd use, perhaps with a 20A fuse on the +ve one to protect them.

And oh, 'auto wire' often is specced including the plastic insulation, so be wary of that. And if you have a solar shop or electrician with some twin-core outdoor 'solar wire', 6mm2 is a stock size, highly insulated, and rugged as hell..

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oscarmax avatar image
oscarmax answered ·

John I am a bit confused my 80w mono solar panels are only rated @ 4.49amp each, 2 x 4.49= 8.98amp?

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oscarmax avatar image
oscarmax answered ·

I have some 4,5mm2 and 6mm2 wire, the new proposed position should be within 8-9 inches of the battery and battery sense.

However relocating the MPPT under the caravan upholstered seat may affect the Bluetooth function..

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