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Do black solar panels perform badly?


To most people, the all black solar panel looks much nicer than a regular panel.
Black solar cells, inside a black frame with a black backing sheet like the Longi panel pictured below.


The black backsheet is what makes the panel look so good, but it also that same backsheet the critics claim is the cause of the problem. Black absorbs heat, making the cells hotter and therefore reducing their ability to make electricity compared to a panel with a white backsheet that reflects heat away from the cells.


It all makes perfect sense.


We decided to check whether the theory fitted reality, and the short answer is that it doesn't. When we compare our customer installation power outputs over the short, medium and long term, the all black panels make exactly the same power as the mono panels with white backsheets. There were sites where the black panels were performing a bit better than average, and sites where they were a bit worse, but that's entirely normal. A few percent either way happens everywhere with any panels, black, blue or otherwise.


What about efficiency?

To explain efficiency, consider this. You have two identically sized panels, both 1.6m high by 1 metre wide. One of them has a maximum power output rating of 330W, the other 300W.
The 330W model is more efficient because it can make more power per square metre of roof space. In real terms if you wanted 6.6kW of panels, you would need 20 of the 330W panels against 22 of the less efficient 300W panels. However, once on the roof, it makes no difference to power outputs, both are 6.6kW in total and will make exactly the same amount of electricity.


So, when we look at most of the all black panels we see that they are slightly less roof space efficient than those with white backsheets. Where we often see 300W all black panels, the same manufacturer has panels with white backsheets rated at 315W. So, 22 all black panels instead of 21 white ones to make 6.6kW.


It's our view that if the panels are on a roof, out of sight, then it makes no difference at all, but if you have panels that you and others can see then an all black panel on a dark roof, looks much better. On light roofs, not so much, in fact on a white roof, an all black panel seems to be even more obvious by its total blackness, but on a darker roof, they blend in much better.


The main point of this FAQ is about whether all black panels make less power, and on a small residential scale of the typical 6.6kW install in Perth, the answer to that, based on real life comparisons, is no they don't make less power. Perhaps on very large installations, solar farms etc, there might be detectable power outputs differences. Don't know, because we don't install solar farms.