losing power with the heat

deacon

Hi guys,
Just want to see what you think.
My 10 80 sharp panels were installed in the end of March. On a bright sunny day I would regularly see 800 watts, sometimes as high as 860 watts.
We have been getting 90* weather lately, and the best I am seeing is 700 watts.
Is that in the normal range for Solar panels in the heat.
The difference is about 30* warmer.
Thanks

The Only Sarge

Re: losing power with the heat

It was 104f here yesterday....and I checked for grins and saw a 13% drop in output from the panels versus last week in the mid-high 80's.

Cariboocoot

Re: losing power with the heat

deacon wrote: »

Hi guys,
Just want to see what you think.
My 10 80 sharp panels were installed in the end of March. On a bright sunny day I would regularly see 800 watts, sometimes as high as 860 watts.
We have been getting 90* weather lately, and the best I am seeing is 700 watts.
Is that in the normal range for Solar panels in the heat.
The difference is about 30* warmer.
Thanks

Yes, it's to be expected.
For one thing, the "nameplate" rating on any panel is determined under lab conditions; controlled temp, short exposure to a known amount of light, calibrated instruments. On average you can expect to s around 75-80% of this rating.
Several factors will distort this. Higher temps will drop output (remember that panel temperature is higher than ambient). Cold temps will increase it. Humidity can diffuse light and reduce peak output. It can also diffuse light and increase over-all daily yield. Likewise pollution will drop readings. Higher elevation will increase output. Edge-of-cloud events can cause a sudden, significant, but fleeting increase in power.

Get the idea? So many factors come in to play! Never will panel output be a consistent value every day; you have to go by averages. 700 Watts from 800 Watts of panel is 87% - far above what we general expect in planning. But remember that how the readings are taken makes a difference too; charge controllers do not have the most accurate Watt readings (because they don't need it to be; the function is an incidental factor of their function).

deacon

Re: losing power with the heat

Thanks Guys. I took the readings from the SCC and the Bogart PentaMetric.