So now I have a solar PV system how do I make the most of it???

John_Pierpoint

Yes it is when you get a hole in thin clouds, full benefit from the direct sunlight plus a nice background glow from the fluffy white stuff.

sly_dog_jonah

I think the reason why bigger peaks are seen when there's broken sunshine is that the panels have time to cool down just prior to the peaks. Sustained sunshine will lead to higher panel temperatures and lower efficiency.

For similar reasons, a cool breeze will help bump up peak output compared to a still day, because the wind cools the panels.

I think any 'reflection' of sunlight from clouds must be so insignificant as to be of no relevance.

Its the temperature of the panels and solar radiation which is most importance.

Cardew

sly_dog_jonah wrote: »

For similar reasons, a cool breeze will help bump up peak output compared to a still day, because the wind cools the panels.

So use your surplus generated electricity to operate a fan to cool down your panels;)

GaryMo_2

A good reason why the likes of 4kWp of panels are matched with 3.68kW inverters.

isolar

Hey thought you might like to check out our cool 'solar uprising game' check it out here i-solar.co.uk > go to 'play solar game' on the left

HalloweenJack

today`s output - 11.8kwh

totals being 476.8kwh for 972h uptime...... not quite my best to date - that was 2 days ago @ 12.9 kwh

invertor was on MPP-Peak from 8.30AM

Cardew

isolar wrote: »

Hey thought you might like to check out our cool 'solar uprising game' check it out here spam.co.uk > go to 'play solar game' on the left

Apart from it being spam, you don't actually install systems but are a middleman getting a slice of the action!

zeupater

sly_dog_jonah wrote: »

I think the reason why bigger peaks are seen when there's broken sunshine is that the panels have time to cool down just prior to the peaks. Sustained sunshine will lead to higher panel temperatures and lower efficiency.

For similar reasons, a cool breeze will help bump up peak output compared to a still day, because the wind cools the panels.

I think any 'reflection' of sunlight from clouds must be so insignificant as to be of no relevance.

Its the temperature of the panels and solar radiation which is most importance.

Hi

'Cloud edge effect' does gain from cooling whilst the panels are shaded, however, when the cloud clears indirect sunlight is refracted through the cloud edge and reflected from other clouds ... this can be measured by light meters but can often be easily seen at the edge of fair weather (cumulus) clouds on a sunny day.

With pv you will notice a high peak as the cloud clears which drops away quite quickly as the cloud edge effect deminishes, followed by a further steady reduction in output as the panel temperature rises.

HTH
Z

sly_dog_jonah

zeupater wrote: »

Hi

'Cloud edge effect' does gain from cooling whilst the panels are shaded, however, when the cloud clears indirect sunlight is refracted through the cloud edge and reflected from other clouds ... this can be measured by light meters but can often be easily seen at the edge of fair weather (cumulus) clouds on a sunny day.

With pv you will notice a high peak as the cloud clears which drops away quite quickly as the cloud edge effect deminishes, followed by a further steady reduction in output as the panel temperature rises.

HTH
Z

Ah refraction and reflection, I stand corrected! I can well believe that refraction can have an effect at the edge of clouds (direct sunlight being added to by sunlight refracted slightly by the edge of the cloud).

But reflection off other clouds? That seems a bit far-fetched to me. Given how much solar radiation drops with just the slightest amount of cloud cover, I find it hard to believe that reflection off clouds can contribute anything measurable. The physisist in me says that's outside the realms of likelihood.

davidanddeirdre

sly_dog_jonah wrote: »

Ah refraction and reflection, I stand corrected! I can well believe that refraction can have an effect at the edge of clouds (direct sunlight being added to by sunlight refracted slightly by the edge of the cloud).

But reflection off other clouds? That seems a bit far-fetched to me. Given how much solar radiation drops with just the slightest amount of cloud cover, I find it hard to believe that reflection off clouds can contribute anything measurable. The physisist in me says that's outside the realms of likelihood.

I can't be totally scientific about this, but anecdotally there certainly seems to be something in reflection off clouds, both from the ground and from sunlight which is otherwise heading in a different direction.

1. When there was significant snowfall a few weeks ago, and I made sure immediately with a brush all the snow was off our panels, we achieved up to about 30% of direct sunlight generation even with an overcast sky, compared with about 20% max which could be expected without ground snow cover
2. Because we face slightly E of SE, we completely lose direct sunlight about 15.30 summertime. With a clear blue sky output quickly drops to <100, whereas with cloud especially thin high cloud it can achieve >200W. Some of our best daily outputs have been with a clear sky up to early afternoon, followed by mid to late afternoon with thin high cloud.