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kgrotenhuis asked

I have 4 solar panels on a sail boat. One will be shaded while at the dock or close quarters. How should I connect them to my MPPT 150/100-MC4 controller

I have a choice to use 3 or 4 MSE415SX6Z mission solar panels. These are 72 cell panels 48.91v open circuit. Originally I was going to just use 3 panels in series as that is what easily fits on my boat. 3 in series would be just under the 150v requirement for open circuit voltage. Then just use 1 set of the MC4 connectors on the controller. This would give me about 1200 watts of power. I have a 4th panel I could install but in close quarters this would need to be stored in the shade to avoid possible damage. I understand the MC4 connectors on the controller to be in parallel. If I used 4 panels I would need to configure 2 sets of 2 panels in series then each set connected to a set of the MC4 connectors (Parallel) on the controller. How will the one shaded panel effect the whole system? Should I just not use the 4th panel or get it its own controller?

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seb71 answered ·

These are 72 cell panels 48.91v open circuit. Originally I was going to just use 3 panels in series as that is what easily fits on my boat. 3 in series would be just under the 150v requirement for open circuit voltage.

That's too close to 150V. Keep in mind that on colder days the Voc can be even higher, so you risk going over 150V.


If I used 4 panels I would need to configure 2 sets of 2 panels in series then each set connected to a set of the MC4 connectors (Parallel) on the controller. How will the one shaded panel effect the whole system?

The shaded panel will bring down the production of that string (of 2 PV panels in series). So it depends how long will be in shade.


What's the battery voltage?

If 12V or 24V, you may consider getting some smaller MPPT charger(s) for the 3rd (and maybe another small MPPT for 4th panel, if you buy a 4th one).

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