Why knowing VOC and cold weather matters.

[jasonhc73]

This is why you have to be extra careful during cold weather and knowing what your MPPT limits are.

The VOC of these panels are 45.4V
The MPPT range is 60~115Vdc. with max VOC at 145Vdc.

This is 2 panels in series setup, just being turned on. (I forgot to turn them on last night after reconfiguring)

As soon as the MPPT activated and started drawing "current" the "voltage" drops and as soon as the panels "warm" the voltage lowers some more.

Just like any well regulated mechanical machine, running anything at its extremes is not a good idea.

 

[snoobler]

Sorry if I'm being dense, but I don't see what you're trying to convey.

The pictures look identical, both showing 88V.
If the Panel Voc is 45.4V, two in series would be about 90.8V.

I would conclude that there are no cold weather issues based on the information you presented.

 

[jasonhc73]

Sorry if I'm being dense, but I don't see what you're trying to convey.

The pictures look identical, both showing 88V.
If the Panel Voc is 45.4V, two in series would be about 90.8V.

I would conclude that there are no cold weather issues based on the information you presented.

Normal warmed up operation is about 65V to 76V

 

[fafrd]

Normal warmed up operation is about 65V to 76V

View attachment 32243

Yes, normal 2-series Vmpp is 65-75V while when first turned on cold you might get voltages as high as 88V.

Your MPPT range is 60-115VDC, so all is OK there even beyond Voc of over 91V and the upper limit of Voc your controller can handle is well beyond that at 145V.

Your system seems well-designed to handle this panel configuration, or is that the point your trying to make (and warning others not to plan for an MPPT range just barely extending past Vmpp)?

 

[snoobler]

Normal warmed up operation is about 65V to 76V

View attachment 32243

Right. Somewhere around Vmp which is probably around 36V for your panels. The voltage lowering has more to do with the MPPT algorithm than cold.

I'm still not seeing the point of this thread. I understand the concepts involved. I am concerned that someone who has no idea, but who could possibly benefit from a "precautionary tale" worthy subject line, will be as clueless as I am about the point of this thread.

And why it's in review/tech support of AiO systems.