The Seasons of Solar Thermal Problems – Summer

Over the years we have received many customer service calls about this or that solar heating system not working.  As we have continued to work with the installers we have developed patterns of problems that follow share a high correlation to the season.  The problems we have faced recently (no surprise) are what I will call the summer problem.  You might be thinking that the summer problem is systems blowing off because they have too much heat but you would be wrong.  Several years ago we figured out how to mitigate that problem and have seen very few cases of it since.  No, the summer problem I am talking about today has to do with differential controllers.


A high percentage of our summer problem calls are related to differential controllers.  The problem solar installers report is that their sensors or controller have stopped working.  Believing the product to be faulty (this is always the first assumption) they call seeking to get a replacement for whatever they believe is defective.  In pretty much every case the solar contractor is providing a temporary patch to the problem rather than actually fixing it.  The actual problem is that the solar loop piping isn’t grounded.  Since the solar loop piping isn’t electrically grounded whenever there is a weather event the collectors on the roof and associated piping acts as a grounding rod for all of the electrostatic energy in the air.  If the piping isn’t grounded enough electrical potential will develop until the static electricity shorts across the sensor or the control to reach electrical ground.  This static discharge is enough to ruin the sensor or the control.  The reason I call this a summer problem is because we get this call in the summer time particularly during periods when there has been a lot of electrical storms.


It doesn’t take a lightning strike to cause your system to fail so be sure to use a ground strap and grounding rod to electrically ground your solar piping to eliminate this problem  By the way, this problem can also kill solar monitoring systems as well.