Solar Panels - What controller and how many GMP to run through the panels?

DjEclipse

Well-known member
Jun 27, 2016
87
Ontario
I have the Pentair Solartouch controller works very well. It shuts down flow to the panels when a cloud comes over, also puts pump into low speed when solar is not available or viable.
My panels/sensor is roughly 75 feet from the controller, i haven't noticed any problems with probe readings, but if I want I can recalibrate the sensors. When the rooftop sensors reads 40+ C temp rise thru the panels is roughly 5 C. I have a laser temp reader.
Thank you for the reply.

Is this the controller you have?

 

Daaaadarz

Member
Apr 30, 2018
10
Randolph, NJ
I have roughly the same size pool with 6 2x20 panels.
Dont expect a great output from these due to lack of panel area and volume of water.
You should use a cover at night and expect one or two degrees gain on the best days.
1800 BTU/ft^2-day(from fafco rating) with 80ft^2 of panels is 144,000 BTU/day
You need 191,000 BTU to raise your pool 1 degree.
Best to spend your money on a heater and Fuel. typical gas heater can do that in 1hr
Hope I didnt dash your dreams. I'm in the same boat but at least the heat is free.
 

Daaaadarz

Member
Apr 30, 2018
10
Randolph, NJ
Also, when your running the solar, put your hand on the panels and feel all over(if you can or use a laser IR thermometer). They should be cool to the touch, any hot spots have trapped air or no/low flow. As long as they feel cool and have water flowing you are getting the full output. The flow requirements are very low to achieve full output on these.
 

DjEclipse

Well-known member
Jun 27, 2016
87
Ontario
I have roughly the same size pool with 6 2x20 panels.
Dont expect a great output from these due to lack of panel area and volume of water.
You should use a cover at night and expect one or two degrees gain on the best days.
1800 BTU/ft^2-day(from fafco rating) with 80ft^2 of panels is 144,000 BTU/day
You need 191,000 BTU to raise your pool 1 degree.
Best to spend your money on a heater and Fuel. typical gas heater can do that in 1hr
Hope I didnt dash your dreams. I'm in the same boat but at least the heat is free.
Where did you get the 1800 BTU/ft^2-day? Is that 1800btu/ sqft per day?

All the panels are cool to the touch on the roof, there are no air pickets, I put a good slant on them so air could it get trapped.

The problem is I have spent probably $1000 ( not including the solar pannels themselves ) in parts due to the long 60' + run from the pump to the roof and I still have to buy a controller to get the proper efficiency out of these things which will be another $500.00 Canadian when it is all said and done.

I'm almost at the same price as a heater $2300.00 but then I need it installed.

I'm going to have to get out the pool cover and try and keep some of this heat in.

The thing is with the cover alone ( nof solar) last season it would get up to 85 (30) on its own.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,615
Pleasanton, CA
1800 BTU/sqft/day is probably the absolute maximum you would get out of panels during the hottest day of the season. Typically, it is closer to 1000 BTU/sqft/day on an average day over the pool season.

If you want to heat that much water without a cover, you would need at least twice the number of panels but then your daily temperature swings would be twice as much as with a cover. The cover keeps the heat you gain over night where as without the cover, you lose most of what is gained during the day. Bottom line is you need a lot more panels without cover than you do with a cover.
 

Daaaadarz

Member
Apr 30, 2018
10
Randolph, NJ
Sources for my figures
This seems to be a pretty high figure and is probably in Arizona summer or something.
This would be a best case scenario i guess.

I have found other testing to show it to be 1000 Btu/sqft-day.

the FSEC testing all have this in them "This collector has been rated for energy output on measured performance and an assumed standard day. Total solar energy available for the standard day is 5045 Watt-hour/m2 (1600 Btu/ft2 ) distributed over a 10 hour period. "
Maybe 1600 is the standard maximum available.

Everything is probably working as well as it can.
I also have the pentair solartouch controller btw.
Recommend the kit with the draining valve to allow the panels to drain out when the valve is closed. Panels will also drain with a normal valve if the valve is slightly open to bypass.