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Why Is Shading Bad For Solar Panels?

by | May 24, 2019

I’m sure you’ve heard that shade is bad for solar panels, and obviously they need sun to perform. But why exactly is shade that bad?

There are actually 2 types of shade you can get, solid shade, like a wall or a chimney, or soft shade, like a tree and the shade from the leaves as they move.

Shade from trees is not great for producing lots of power.  However if there is only some shade the bypass diodes on the back of the panel will kick in, and you will still produce a reasonable amount of power.

However, if you have hard shade, like a chimney or a wall, this works very differently.  shading on solar panels adelaide

Let me show you a system we went to a while ago, and the customer had no idea he had a problem.  He couldn’t see the panels properly from the ground.  We were actually called out to remove the panels and relocate to another roof.

As you can see the chimney is shading 2 of the panels which are directly behind it. As the sun moves, all 3 of the panels behind the chimney get shaded at different times.

What about the bypass diodes you may ask?  Often sales people will tell you not to worry, the bypass diode will kick in, and you will lose hardly any performance, so not a problem.

Solar Fire Hazard

However, what is happening as the shade moves over, particularly at the angle you can see here, the bypass diodes are struggling.  Give it 5 years, and you will have burn marks and hot spots on your panels. This really affects the performance, and it is a fire hazard. If you have leaves or anything flammable under the panel you have a potential roof fire in the making.

However, not only that, but panel manufacturers will not cover them under warranty, as they are not installed to their instructions.

Here are the 3 panels you see, once we took them off the roof.

solar panels with hotspots Adelaide

Close up View of the hotspots on the panels

solar panels with hotspots adelaide

3 Solar Panels With Hotspots

What can you do?

If you are buying a new system, be very mindful of this, as in a few years time you will almost certainly have a problem.  If there is no alternative but to put panels in shade, you can stop this happening, and make the system perform better by installing either optimizers or micro inverters.

What about if you already have panels on your roof, and they are shaded like this?  Well, firstly, get your panels checked for any sign of a problem, and if you have you need to remove or bypass these panels NOW.

1. Can you remove the item that is shading the panels?  This is sometimes an option.  It could mean relocating a satellite dish, or cutting down a chimney.  However this is not always possible.

2. Relocate the panels to another, unshaded part of the roof.

3. Add optimizers to your system.  This involves installing an optimizer under the panel, and will ensure it works independently.  It is possible in some cases to just install an optimizer under the shaded panels, so can be a good option.

If you are in Adelaide and the surrounding areas and need help with this, call us today on 1300 130 546.