Solar panels not draining when pump is running

lborne

Well-known member
Jun 29, 2009
467
Vero Beach, FL
I have the temperature set for 86 and what typically happens is the pool cools overnight, the pump comes on about 11 am and the controller diverts the water to the panels. Sometime later in the afternoon the temperature reaches the set point and the valve is turned so no water can go up to the panels. I was in the pool about 4 pm and decided to turn the temp up. The water that came out of the returns was scalding hot. It had been sitting up in the panels for a few hours - that can't be good for the panels.
My solar panels are plumbed correctly with a valve to either divert water to them, or bypass them. The return has a check valve so water can't go into the panels when the valve is in bypass mode. The problem is that the pump pressure keeps the check valve closed and so the panels stay full. Once the pump shuts off, the panels drain completely. What am I doing wrong?
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
That sounds like normal operation. Not ideal, but there is no way for the panels to drain while the pump is running.
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,413
Morris Cnty NJ
you would have to change the timing to allow the pump to stop so the panels would drain. the problem is that depending on temp that could be at any time of the day. my solar does the same thing and so does everybody elses. look up your panels online and take a look at the specs. i think they are rated for over 200degrees even with some pressure behind them from pump. shouldnt be an issue really
 

lborne

Well-known member
Jun 29, 2009
467
Vero Beach, FL
you would have to change the timing to allow the pump to stop so the panels would drain. the problem is that depending on temp that could be at any time of the day. my solar does the same thing and so does everybody elses. look up your panels online and take a look at the specs. i think they are rated for over 200degrees even with some pressure behind them from pump. shouldnt be an issue really
I was thinking of adding a second valve on the return so that when solar is shut off, the panels are removed from seeing any pump pressure and then dumping the solar water back into the pool - but it would require the addition of another return line, or I could use the vac line except for that code required cap needed on the input of the vac line. Not sure any of this is worth it.
 
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