Overheating Solar Panels

On the 2021 cruise I was disappointed in the output from the new solar panels.  When first installed the panels performed perfectly, putting out the expected amps.  Somehow, the output from the panels seemed to have degraded at the same time that we had good summer sunlight conditions.

The panels were mounted almost one year ago directly onto the hard dodger.  I had noticed that the underside of the dodger was getting warm under the panels in sunny weather.  Could the panels be overheating causing the output to degrade?  An inspection under the panels revealed just how high the temperature had been getting, the paint on the dodger top was blistering.

After a few weeks thinking about the overheating problem I thought I had a solution.  I needed to provide an air gap between the solar panel and the dodger top. To separate the solar panel from the dodger a sheet of corflute looked like an answer. Corflute is widely used in signage and can be obtained cheaply from most hardware stores.  I had a look at some Corflute and was not too impressed.  It’s a polypropylene material and not really robust enough for the marine environment.

After some more thought and beer I hit on the solution.  There is a product called Twinwall, it’s a clear polycarbonate sheet used in roofing and has square section channels.  Perfect for circulating air and dissipating heat.  The product has a fifteen year warranty for roofing applications so should last the course. Its strong, flexible and with the square shaped channels will be perfect for use under solar panels.

The local stockist had a 6mm Twinwall offcut which he gave me for free, just charging me twenty dollars for cutting it the exact size of the two solar panels.  A good deal.

Mounting the twinwall under the panels was an easy job.  I unscrewed the panels from the dodger top and slipped the twinwall sheets underneath.  The 3/4’” screws were replaced with 1” screws to account for the extre thickness of the twinwall.  I used 3M 4000 sealant around the screws, both underneath the twinwasll and between the twinwall and the panels.

The channels in the twinwall run fore and aft to take advantage of the airflow that normally runs from ahead when at anchor.  In this way the twinwall acts like a large flat heat exchanger.  I expect that over time the twinwall may become blocked with dirt and salt but a quick squirt with a hosepipe should clean it out. 

Both solar panels are now operating at a lower temperature and the output is back to normal.  An easy fix but it took a while for me to figure it out.

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