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No fancy datalogging here. But the annual logs are interesting nonetheless.

This set of panels is interesting as it's logged in November, so, after the bulk of a year's generation.



Topest year; 2018, closely followed by this, 2022 year.

A south facing 4kwp 3.68 limited array in north Cornwall. Unfortunately it's so high up it's never been cleaned. Pleased to see it's not dropped off noticeably.

I love it, no APPS, CLOUD, WIFFY, GOOGLE, ALGRITHMS or any other nonsense, just a bit of readable paper, a man after my heart

Desp

Bu99er. Thought I’d talk about the wood store


There again, analogue can be very comfortable

Gareth J wrote: ↑Sun Nov 20, 2022 2:31 pm
Pleased to see it's not dropped off noticeably.

It is very hard to determine the amount of degradation of solar panels.

The biggest influence on the annual generation is the annual sunshine hours. In your case there are monthly totals on the Met Office website for Camborne and Chivenor. There is also the question of the quality of the sunshine. Bright or hazy, morning or afternoon (especially for non-south facing roofs and shading issues), summer or winter etc. over several years one can expect quality to average out.

Thus kWh per kWp per hour of sunshine is a useful measure.

The next biggest influence is probably temperature. The higher the temperature the lower the efficiency of solar panels. More sunshine hours equals higher temperature and thus a lower kWh/kWp/sunshinehr.

All in all even after over 12 years of data. I cannot meaningfully determine how much degradation my solar panels have suffered.

John

John_S wrote: ↑Sun Nov 20, 2022 10:58 pm All in all even after over 12 years of data. I cannot meaningfully determine how much degradation my solar panels have suffered.

I’ve seen lots of people with arrays over 10 years old who cannot detect any deg whatsoever certainly it is within the normal variation from one year to another with recent “record years”. I’m leaning heavily towards real world deg being much less than thought.

Stinsy wrote: ↑Mon Nov 21, 2022 9:41 am

John_S wrote: ↑Sun Nov 20, 2022 10:58 pm All in all even after over 12 years of data. I cannot meaningfully determine how much degradation my solar panels have suffered.

I’ve seen lots of people with arrays over 10 years old who cannot detect any deg whatsoever certainly it is within the normal variation from one year to another with recent “record years”. I’m leaning heavily towards real world deg being much less than thought.

I agree, our system has been generating around 6,000kWh/year consistently each year since it was installed in 2014. There's a few percent variation from year to year, but no obvious downward trend. If there is some panel degradation then it looks as if it is less than the normal variation from year to year, so probably isn't worth worrying about too much.