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Afternoon.

I have potential customer questioning whether all black panels will perform as well as panels with a white backing on the basis that they will become hotter more quickly affecting energy generation on warm sunny days.

I can understand the logic but have never seen hard evidence to suggest that there would be a significant difference, does anyone have any information/views?

Cheers Andrew
 
Afternoon.

I have potential customer questioning whether all black panels will perform as well as panels with a white backing on the basis that they will become hotter more quickly affecting energy generation on warm sunny days.

I can understand the logic but have never seen hard evidence to suggest that there would be a significant difference, does anyone have any information/views?

Cheers Andrew

What are the panels actually doing - or what are they for?
 
Difference in output will be neglible.

I presume you mean over a year, do you have anything to back this up? It makes sense to me that a black back panel might absorb more heat and therefore this could impact on generation levels but I am not clear to what extent this might be the case over a white backed panel.
 
it will absorb more heat, but only really in the white bits, which isn't where the cells are, so I'd expect a few degrees temperature difference between the cells in the panels, but not very much, so maybe 1-2% of difference in peak sunlight output levels at worst.
 
I don't know about the panels being offered today and i've never seen white PV panels, but the PV panels of a few years back were well and truly influenced by heat, and lost quite a bit in output efficiency when Panel temperatures rose above a certain level !!

One of the reasons why you didn't see much in the way of PV installations in the Middle East, (you would think that they would take advantage of free solar power) where the ambient temperatures often exceed 40C. You could quite easily fry eggs on the panels quicker than on an induction hob!! ...lol!!

I'll leave it to the PV boys here to add their working knowledge of PV panels with regards to heat vs efficiency. Probably not so much of a problem in the UK, as it might be in say Southern Europe...
 
I don't know about the panels being offered today and i've never seen white PV panels, but the PV panels of a few years back were well and truly influenced by heat, and lost quite a bit in output efficiency when Panel temperatures rose above a certain level !!

One of the reasons why you didn't see much in the way of PV installations in the Middle East, (you would think that they would take advantage of free solar power) where the ambient temperatures often exceed 40C. You could quite easily fry eggs on the panels quicker than on an induction hob!! ...lol!!

I'll leave it to the PV boys here to add their working knowledge of PV panels with regards to heat vs efficiency. Probably not so much of a problem in the UK, as it might be in say Southern Europe...

Yes, I take your point about the effects of ambient on PV output.
I (mis)read the first post as the OP wanting to collect heat hence the black.



Here's a link to a paper:

The Effects of Solar Irradience and Ambient Temperature on Solar PV Moule Output in Northern Ghana | Aburiya | Ghana Journal of Development Studies

You would probably have pay for the full paper but the abstract has this:

Ambient temperatures above 30oC cause a slight (5 - 9%) decrease in output
 
Black panels are going to absorb heat and so their temperature would be above that of 'less black' panels and (well?) above ambient. If you've ever watched Formula 1 you'll have heard the track temperature (black tarmac) quoted as well above air temperature.

The graphs produced at PV potential estimation utility show the temperature effect quite nicely with a dip in output for May to July rather than the the rise you might expect.
 
Thanks for the input everyone, very useful.

I think we're all agreed higher temperatures imped energy generation, the question is how much more is lost through the (potentially) higher temperature of a black backed panel over a white backed panel.

I'm inclined to agree with Gavin & Gary that the difference will be relatively small in the UK, although possibly more significant in sunnier climates.

Thanks again.

Andrew
 
Check out the graphs I referred to above and you may think that the loss will be more than 9-10%. Even at that level, that's a loss in the most productive months. 9-10% in December doesn't amount to much but in the middle of summer...
 
Check out the graphs I referred to above and you may think that the loss will be more than 9-10%. Even at that level, that's a loss in the most productive months. 9-10% in December doesn't amount to much but in the middle of summer...

Hi Digital48 - I think there may be some confusion here. I don't disagree that a system might have losses of 9-10% or more due to excessive heat (I've heard of worse). The 1-2% referred to above is the possible/guestimated difference between the energy loss on a black backed panel and a white backed panel i.e. if the white backed panel loses 10% due to excessive heat, a black backed panel could lose 12% in the same conditions.
 
Why not just look at the data sheet and work out losses above 25 degrees.
Also doesn't heat effect cell degradation
There must be reason why REC wont make a full black panel.
 
Why not just look at the data sheet and work out losses above 25 degrees.
Also doesn't heat effect cell degradation
There must be reason why REC wont make a full black panel.

I've had a look at various data sheets and I can't see any real difference between the losses on an all black panel and one with a white back. Also plenty of manufacturers put both types of panel on the same data sheet which suggests no difference at all.

I take your point about REC although to my (limited) knowledge no other manufacturer has made such a statement and plenty of other produce both.
 
Had a discussion with JA Solar about this at one exhibition. They use a slightly higher output cell around the edge of all black panels to compensate for the potential loss due to higher operating temperatures. It is the panel temperature, not ambient temperature that is important. If you have ever done a full test for VOC and ISC, taken irradiance and temperature readings to extrapolate back to STC, it is surprising just how warm panels can get - 40deg C very common.

I don't think it is a big issue if you are using a quality panel. There is some cheap as chips All Black around at the moment - as always, you will get what you pay for.
 

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