Wiring of solar panels to mppt controller question

babybober said:

Hi, I have qty 6 100w hqst mono panels that will feed a 50 amp mppt controller to 12v batteries. The controller is a 100v open panel voltage. The panels will be mounted on the roof of my 5th wheel camper. We often camp in wooded areas not open fields with full sun. So, my question is should I wire the panels in a 3s2p setup or 2s3p setup knowing that some panels may be shaded. After the combiner I will be running 8 ga wire from the roof down to the controller (under 20’ and probably more like 15’ run).
Thanks.

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Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

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Forbisher said:

2S3P only needs 10 awg at 20' for 1.89% voltage drop.
3S2P is only about 1% voltage drop.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

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Batterypack said:

Check VOC of MPPT. Can it handle volts of 3 panels in series?

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mikefitz said:

The controller will handle either of the panel combinations. Wire gauge on the relatively short run wont matter much. Technically shade will effect series panels more than parallel connected, although in my boating and RV experience there is no significant difference, any shade will lose power, often significantly. If you want power from solar you need sun on the panels.

I would go for the 2S3P, as slightly better for shading , the volt drops between panels and controller are still quite small and the input voltage corresponds near to the maximum conversion efficiency of the controller.

With multiple strings, using a separate MPPT controller for each string may harvest more energy. (where varying solar conditions exist across the array).

Mike

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Batterypack said:

Check VOC of MPPT. Can it handle volts of 3 panels in series?

Click to expand...