Single voltage power point setting - Set to VMP or is there more nuance to it?

I am thinking about overpanel designs and conductor sizing, whether intermediate conductors could be sized for max power draw, rather than max power supply, and then fused appropriately to protect the wires if max draw was ever exceeded.

One of the hurdles of that design would be if the MPPT searches low voltage and high amperage power points, which would be available and would blow the OCP.

To prevent this happening, the charge controller could be set to a set to a single voltage power point so that it does not go searching. I have heard that single voltage configurations can perform better than expected, with only minor production losses compared to power point tracking.

Does anyone have experience with theory and is there anything more to it than just going off the VMP spec of the panel and setting it to VMP times panels in series?

Would be an interesting test to determine if the MPPT algorithm really does produce more power vs. a fixed Voltage setting.

That said, IMHO you are over thinking things based on the fact that Isc of most PV panels is not significantly higher than Imp therefore its not possible for the PV to generate excess current and trip the OCP.

BentleyJ said:

That said, IMHO you are over thinking things based on the fact that Isc of most PV panels is not significantly higher than Imp therefore its not possible for the PV to generate excess current and trip the OCP.

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I'm actually thinking of significant over-paneling configurations, like a 35 amp array on a 20 amp fuse, because the charge controller is never expected to draw more than 16 amps at the set voltage. But if the CC was searching it would have the opportunity to find 35 amp power points.

And I do mean a 20 amp fuse on the combined circuit, not the branches. It's for combined conductor protection, not string protection.

I think you may be shooting yourself in the foot.


I've noticed that on bad solar days (when you want to be overpaneled) the mppt runs at a lower voltage. So you'd be giving up production when you need it most.

For example, when I was producing 7kW two days ago my strings were at 275v and 321v. Today, at 1kW they are at 246v and 283v.

DougfromdaUP said:

I've noticed that on bad solar days (when you want to be overpaneled) the mppt runs at a lower voltage. So you'd be giving up production when you need it most.

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Yeah that would be the nuance. But it could be that the lower voltage works well enough to run all the time, giving up good day production instead.