What the Guru says
My 10-year solar system panels got some brown spots on them – like someone burned them with a cigarette. What’s the issue? What do I do next?
Brown spots on a solar panel are a really interesting one.
I'm going to day say two things. Number one, check your solar panels are clean, especially if you live in an area with lots of gum trees or cicadas.
Brown spots usually are a sign that something's going pretty wrong. It's usually a sign of a burn mark underneath. Definitely worth getting your installer out to have a good look.
If you see brown spots on your solar panel, one reason is relatively harmless and another is serious. It’s important to investigate this promptly.
The 1st reason could be a deposit from trees or animals on the glass of the panel zap from gum trees, or bat poo looks brown and bakes onto the panel’s surface. Or a cicada shell could look like a brown spot from a distance.
If you have eliminated these two options and it looks more like a burn mark, especially if it also appears on the back of the panel on the white backing sheet, then this is a hot spot.
Panels can develop hot spots after a few years on the roof because of ongoing hard shadows hitting the panel or due to damage in the panel’s cells.
A hot spot is, as the name says, a local spot on the panel that heats up more than the surrounding area. The reason is that the electricity in the panel has found some resistance, for example, when there is a gap in a cell due to a micro-crack and the electrons can not flow freely, the power turns into heat.
Over time you get a runaway effect, and that particular area gets hotter and hotter till it starts to burn the backing sheet and maybe even crack the glass in front of the panel.
So what can you do?
- Only go close to the panels if access can be gained safely. Otherwise, contact a local solar installer for an inspection.
- Check if your system has lost production by comparing annual output data from previous years and now.
- If you can get access easily, establish if the brown spots are on top of the panels or below in the cell. If above the panels, we suggest cleaning the panels with warm water and some glass cleaner/dishwashing liquid.
- If below the glass, take photos and contact your local solar company for a diagnosis and advice. If possible, arrange a sit inspection for further diagnosis. If this is a product warranty claim, you might also seek to send the photos to the panel manufacturer for feedback.
