Panel volts in cold weather

[grebaba]

I have my 12 panels in series and they sticker on them says 38.6 volts per panel.
The spec's. say the voc temp is -.31%c. Jinko 265 Watt panels.
How do I figure the cold temp max voltage these will put out. I am not smart enough to figure it out on my own.
My AIO says it will take 500 volts.
Thanks
Greg

 

[Bob B]

Will Covers that in this recent video

 

[glandpuck]

I have my 12 panels in series and they sticker on them says 38.6 volts per panel.
The spec's. say the voc temp is -.31%c. Jinko 265 Watt panels.
How do I figure the cold temp max voltage these will put out. I am not smart enough to figure it out on my own.
My AIO says it will take 500 volts.
Thanks
Greg

Greg, you are truly smarter than you think because you asked for help instead of being a self proclaimed know it all!

So Voc is open circuit voltage. This is the voltage between the PV+ and PV- when no current is flowing. A physical property of silicon solar cells is that this voltage can go up or down depending on ambient temperature. By agreement, the midpoint of the scale for measurement is 77 degrees F. This is 25 degrees C. Your Voc is calculated to drop 0.31% for each degree centigrade over 25 at the panel surface and to rise by that amount for each degree C below 25 at the panel surface. Say the temperature is 32 F or 0 C. Then we would have 0.31 x 25 = 7.75 + 38.6 so your panel Voc would be 46.35. Again, it is the temperature at the surface of the panel, not the air temperature. Sunshine on a panel can warm it up considerably more that what the air temperature is around the panel.
Now, if you are in the "heat dome" and your temperature is 102 F and the sun is out making your panel surface temperature 130 F, then your Voc will drop as follows: 130F = 54 .4 C. 54.4-25 = 29.4 29.4 x 0.31 = 7.87 38.6 - 7.87 = 30.73 So your Voc with a surface temperature will drop to an expected 30.73 volts.

Hope this helps.

 

[bolhuijo]

Your Voc is calculated to drop 0.31% for each degree centigrade over 25 at the panel surface and to rise by that amount for each degree C below 25 at the panel surface. Say the temperature is 32 F or 0 C. Then we would have 0.31 x 25 = 7.75 + 38.6 so your panel Voc would be 46.35.

The way I read that is 0.31% of 38.6 Voc = 0.1197 Volts per degree. So 25 degrees colder gives 25 * 0.1197 or 3V additional, for 41.6V total.

 

[glandpuck]

The way I read that is 0.31% of 38.6 Voc = 0.1197 Volts per degree. So 25 degrees colder gives 25 * 0.1197 or 3V additional, for 41.6V total.

You may be reading it that way, but that is not correct. I know this because I have diligently measured Voc on my panels for 8 years in winter weather and summer weather.

From the infallible internet Googler:

"It specifically quantifies the loss in power output when a solar panel's temperature surpasses the 25°C (77°F) baseline set under Standard Test Conditions (STC). Typically, the temperature coefficient is articulated as a percentage change per degree Celsius (%/°C) or per degree Fahrenheit (%/°F)."

 

[Danke]

Solar Panel Maximum Voltage Calculator - Footprint Hero

Calculate the maximum open circuit voltage of your solar array. Find your max solar panel voltage to correctly size your solar charge controller.

footprinthero.com