Is it getting too hot for solar panels?

[Social Media]

DUP MP Sammy Wilson has tweeted: "The UK has had to start coal fired generators during this heatwave because the sun is too strong and solar panels have had to be taken offline."

This isn't true.

While it's correct that solar panels are less efficient at hot temperatures, this reduction is relatively small, and was not the main reason for firing up coal power stations.

We spoke to Mr Wilson, who confirmed that the article he had read said that there was a "severe" fall in output, not that the panels had to be taken offline.

According to Solar Energy UK, solar panel performance falls by 0.34 percentage points for every degree that the temperature rises above 25C.

It also said that the longer days and clearer skies mean solar power generates much more electricity during the summer, even if the efficiency falls.

 

On Monday 12 June, coal power was used for the first time in 46 days, but solar power still generated around one-fifth of the UK's electricity during the middle part of the day.

 

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[KhunLA]

Mine will operate efficiently up to 40-44°C, so no worries here.

"Nominal Module Operating Temperature (NMOT) 42 ± 2°C"

 

Rarely does the temp hit 40, and unless near 45, still no worries.

My ESSs are topped up well before noon on sunny days, so even it temps got silly high, it wouldn't be a problem. (production / blue till ESSs topped up)

 

[Crossy]

Just so you recognise who to slap upside the head!

 

[KhunLA]

"According to Solar Energy UK, solar panel performance falls by 0.34 percentage points for every degree that the temperature rises above 25C." ????

 

[007 RED]

3 hours ago, KhunLA said:

"According to Solar Energy UK, solar panel performance falls by 0.34 percentage points for every degree that the temperature rises above 25C." ????

The efficiency drop which they quote is about right for most solar panels, bearing in mind that the tests to establish the output rating for panel will have been done under laboratory conditions with a precise light source projected perpendicularly onto the the photo cell which is maintained at precisely 25^oC.

 

What they seem to forget is that in the real world although the ambient temperature is say 25^oC, the actual temperature of the panel can in fact be considerably higher due to the panel absorbing heat radiated by the sun.

 

Late last year I was concerned that my system didn't seem to be performing as well as I expected.  In theory my 4 x 415W panels should be capable of producing 1,660W when the sun is at its highest point (e.g. mid day) with no clouds, but I was lucky if the system was producing 1,400W, which represents an efficiency loss of  approximately 16%.

 

I decided to do a none scientific test.  At mid day there was good strong sunshine with no clouds/haze.  The ambient temperature in the shade (under the car port) was 30^oC.  I climbed onto the roof of the car port and using an 'cheap' electronic temperature gun (same type used to measure people's temperature during the Covid lockdown) I took a number of readings pointing the gun close to the glass of the panels.  I have attached below a photo of the lowest reading.

 

As will be seen above, the temperature of the panel(s) is shown at just over 63^oC.  This being 38^oC above the panel's laboratory test figure of 25^oC.  My panels have a temperature coefficient = -0.37%/^oC.  Hence, 38 x 0.37 indicates a 14% reduction in efficiency, which accounts for the lower output from the panels.

 

So its fair to say that a nice sunny day can actually decrease the efficiency of the panels.

 

[Jenkins9039]

On generic sunny days -> 

 

5,000kw system (14 x 400w panels) 

 

Will be adding additional 7 550w panels on other side of the house to fill the void in the morning and evening.

 

Also have 300l solar water heater system.

[Pink7]

I have a feeling that Thailand just get hotter for every year..

 

 

 

Pink

[Jenkins9039]

35 minutes ago, Pink7 said:

I have a feeling that Thailand just get hotter for every year..

 

 

 

Pink

Which means more sunlight = more energy production.