Panels test different than summer time

KhellSk

Hello everyone,

I have these panels that last summer with full sun on, tested 20v and 3.3 amps

Did the same thing couple days ago (winter) with clear sky facing sun as well

Tested 20v 1.25amps
@Photowhit ( panels alone, no load ,no battery, no charger)

Whats going on ?

Photowhit

Are you testing them 'short circuit' not connected to anything? Or are these measurements off a charge controller?

Estragon

Winter sun is much weaker than summer in most places that get snow.

BB.

It is amazing, but by our eyes, a 50% reduction in light is barely perceptible.

Low winter sun angle, any haze/smoke/clouds, and you will get reduced current (Isc is more or less proportional to the amount of sun on the panel).

If all of your identical panels are reading the same Isc current (short circuit current), then all is fine. If you have one panel that is reading 50% or less of the Isc of others measured in the same place, same angle, and same time--Then that panel (or its connections) are questionable.

-Bill

KhellSk

BB. said:

If all of your identical panels are reading the same Isc current (short circuit current), then all is fine. If you have one panel that is reading 50% or less of the Isc of others measured in the same place, same angle, and same time--Then that panel (or its connections) are questionable.

-Bill

All are approx the same. Its impressive that it isnt perceptible like you said. I really wonder what people do during winter... my charge controller cannot take more than 400w. To compensate for the lack of luminosity i would need to double my array but a charge controller is limited.


How would one find a good balance  between C rate and amd wattage winter compensation

BB.

PWM controllers do not have the ability to regulate the "extra current" from a solar array. You are stuck following their array configuration requirements.

MPPT type controllers are more flexible--And you can over panel to a degree just fine. There are secondary issues (any electronic device running at max current gets warmer than one running at 80% of rated current--Extra heat is always a difficulty... Can cause shorter life for electronics, especially if there is poor cooling / warm closet space). Oversize array in hot summer climate in a hot garage/battery shed--Your choice...

-Bill

KhellSk

Thank you

softdown

Have you adjusted your panel tilt for the changing orientation of the sun? In my area, accurate orientation varies from ~ 22 degrees in June to ~52 degrees in December.