Solar Panels vs Wind Turbines

[servodude]

Solar PV cells work based on light and not with the heat of the sun; hence it hardly matters if it is cold, cloudy or foggy.

Cold makes no difference, the other 2 a massive one. You need bright direct uninterruptes sunlightto get a decent output.

Scotland gets a similar amount of irradiance to Germany, which has the largest PV market in the world.

In the summertime the sun can stay up until after 10pm though in the winter it can disappear at 4pm so the issue is about generating supply at times when it isn't needed.

The incidental angle of the sun also makes quite a difference. The further North you go the lower the angle of the sun, markedly so away from the midsummer.

A friend in Perth gets similar total output to me in summer apparently (looking at August last year) but since then has lagged. He's catching up now, but even with his longer daylight it seems the hours of bright direct sunlight are not really any longer and his incidental angle is lower than ours.
https://www.timeanddate.com/sun/uk/shrewsbury lets you play with locations, even with our largely East facing array output declines dramatically an hour or so before daylight ends as the sun drops.

Maybe he needs a steeper roof.

Paul

Totally agree!
cloud is THE solar killer (and can be tricky to cope with in MPPT schemes)

Then angle - you want the rays normal in incidence to minimise reflection; depending on the array and use case it might even be worth motorising the panels for this

Temperature has an effect but less so than on batteries that are normally deployed with the panels I've had to play with

[Nocton]

Yes, temperature has a definite effect. We find with our panels, located in sunny Lincolnshire, that in the summer near midday the output graph is often flat, like Table Mountain, as the very hot panels are less efficient. We also have solar thermal panels, which are much more efficient than solar at capturing the sun's energy, and their panel surface temp can easily reach over 100C in summer.

[servodude]

Yes, temperature has a definite effect. We find with our panels, located in sunny Lincolnshire, that in the summer near midday the output graph is often flat, like Table Mountain, as the very hot panels are less efficient. We also have solar thermal panels, which are much more efficient than solar at capturing the sun's energy, and their panel surface temp can easily reach over 100C in summer.

Couldn't the just be saturating the output?
If it was really being hit hard by the temp you'd see it slope down as the panel warmed during the day

[DrFfybes]

Yes, temperature has a definite effect. We find with our panels, located in sunny Lincolnshire, that in the summer near midday the output graph is often flat, like Table Mountain, as the very hot panels are less efficient.

Perhaps daft questions, but...

Is the output capped by the inverter rather than the panels? - I know my niece has a 20 panel install (8kW) but is discovering that in order to avoid getting a G99 export licence they installed a 3.6(?)kW inverter.

When the output plateaus, if not inverter capped, what percentage of the theoretical max panel output is it? AIUI panels generally don't sit t their max.

f it was really being hit hard by the temp you'd see it slope down as the panel warmed during the day

This was my other thought on your observation.

Paul

[Nocton]

I can't answer these questions, but your suggestions may be correct. I'll look into it more this summer. However, the installer suggested it was a temperature effect, i.e. the panels are less efficient when hot.