Too much voltage for my MPPT?

[JanC]

Hi, I have a Victron Smartsolar 150/35 and I have two 485w solar panels wired in series. I'm considering upgrading my solar system with one extra solar panel that fit's the amperage of the other panels and I want to wire it in series with the residual two panels. The VOC would be 129v. It seems somewhat close to the limits of my MPPT considering it can get to -8° C or 17°F in my area.

What I don't understand fully is this- The voltage of the panels rises only when there is sunshine, so there would have to be -8°C/17°F during the top sunshine hours to create voltage too close to 150v limit of my MPPT. And that is impossible in my area. -8°C/°17°F is the record night time temperature during the winter months. So if my assumption is correct, there is no danger in having 129v panel array with 150v MPPT in my case, is it?

I'd be grateful for any advice

Jan

 

[JWLV]

If it's -8°C at night, right when the sun comes out in the morning it still might be pretty close to -8°C. But as the sun comes out (it does not necessarily have to shine directly on your solar panels), your panels will have a voltage although very low amperage. This is the critical time when it might go over your MPPT's VoC limit. Voltage and amperage are separate. There could be high voltage and low amperage at certain times. In the morning is usually that time. The label on your panels state a VoC based on a standard test environment. I believe it is 20°C. If your environment is -8°C, the VoC of your panel will be much higher than what the label says.

 

[TomC4306]

Upgrade with 2 panels, serial connected to one another then, wire them in parallel with an mc4 branch connector to the original pair.