Some of my solar panels are warm to the touch. What’s going on?

Slippery

Active member
Jul 15, 2018
27
Portland or
I have 5 4x10 solar panels that I moved to a sunnier location 2 days ago and the pool is still struggling to warm up. Pump had been on for a few hours when I went out to touch them and found that 2 were cool and 3 were warm to the touch. That tells me that somethings off. But what is it?
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
3,882
Damascus, MD
Your panels will be lucky to give you a degree or 2 per day. If you don't cover the pool at night you'll not gain much at all. How big is your pool?
 

Teald024

TFP Guide
It sounds like the flow isn't balanced across the panels. The hot panels aren't getting enough flow through them. The panels shouldn't feel hot when operating properly.

You have plenty of surface area on the panels to heat your 4400 gallon pool. If the panels are getting full sun then you should be seeing a few degrees per day temp rise. Make sure you cover the pool when possible to prevent evaporation from cooling the pool when windy or at night.
 

ashtonfitzgerald

Well-known member
Sep 27, 2016
207
Oshawa, ON, Canada
If the panels are plumbed in parallel, they should all be the same temperature to your touch unless there is a blockage stopping water from moving through the panel. Air trapped in the panel can slow/stop flow through as can a physical blockage from debris. You'll have to check them to ensure they're each clear and then prime them appropriately.
 

Slippery

Active member
Jul 15, 2018
27
Portland or
If the panels are plumbed in parallel, they should all be the same temperature to your touch unless there is a blockage stopping water from moving through the panel. Air trapped in the panel can slow/stop flow through as can a physical blockage from debris. You'll have to check them to ensure they're each clear and then prime them appropriately.
This is my guess. What does it mean to prime the panels? How does one remove the air?
 

ashtonfitzgerald

Well-known member
Sep 27, 2016
207
Oshawa, ON, Canada
The priming process basically fills the panels with water (removes all air from the system) and the steps depend on how your panels are plumbed.

With my DIY system I need to adjust my diverter to max flow through the system (this won't damage mine as it is designed to handle the pump capacity and pressure) for a few minutes before reducing the flow to a normal level. This flushes most of the air out on it's own.

Pro designed systems that are roof mounted usually have a bleeder valve at the top of the system which allow the panels to gravity drain when the pump/diverter isn't pushing water through the panels. If this is stuck closed, air in the system won't Ben able to vent. Check the bleeder valve operation while the pump is off and while it's running.

Once you know things are operating, you may need to increase the pump speed in order to push enough water through to purge the air. Once primed a slower flow will function fine.

Before I upgraded my pump I used to prime my panels at the start of the season using a garden hose as it gave me more flow than my anemic intex pump.

If the panels are in series (plumbed so water goes through one panel at a time) it is normal for each panel to be hotter than the previous as the water gets warmer the further it travels through the solar.

Please post a pic of your setup and we can probably give more direct advice.
 

Slippery

Active member
Jul 15, 2018
27
Portland or
The priming process basically fills the panels with water (removes all air from the system) and the steps depend on how your panels are plumbed.

With my DIY system I need to adjust my diverter to max flow through the system (this won't damage mine as it is designed to handle the pump capacity and pressure) for a few minutes before reducing the flow to a normal level. This flushes most of the air out on it's own.

Pro designed systems that are roof mounted usually have a bleeder valve at the top of the system which allow the panels to gravity drain when the pump/diverter isn't pushing water through the panels. If this is stuck closed, air in the system won't Ben able to vent. Check the bleeder valve operation while the pump is off and while it's running.

Once you know things are operating, you may need to increase the pump speed in order to push enough water through to purge the air. Once primed a slower flow will function fine.

Before I upgraded my pump I used to prime my panels at the start of the season using a garden hose as it gave me more flow than my anemic intex pump.

If the panels are in series (plumbed so water goes through one panel at a time) it is normal for each panel to be hotter than the previous as the water gets warmer the further it travels through the solar.

Please post a pic of your setup and we can probably give more direct advice.
Thanks! This is great info. Is there a device I can install at the highest point of my panels that will automatically bleed air out and not water when the pump is on?

I was able to bleed a surprising amount of air out of the top yesterday and the panels cooled down immediately. Right now there is a valve that lets air when there is no water flowing installed at the highest point.
 

ashtonfitzgerald

Well-known member
Sep 27, 2016
207
Oshawa, ON, Canada
Am I correct in understanding you already have a vacuum release valve on the solar system? I.e it allows air into the system so that's water can drain when the pump is off? This is an example of one: Amazon.com: HELIOCOL 3/4" New Vacuum Relief Valve Pool Solar Panels - New White: Garden & Outdoor

If so, it should be able to bleed the air from the system as well IF it's properly installed. The relief valve needs to be at the highest point of the system and placed so that as water fills the panels (from bottom to top), air is bled slowly through the valve. Once water hits it, the valve is pushed closed.

Pictures of your setup will help a lot.
 

Slippery

Active member
Jul 15, 2018
27
Portland or
I ended up creating a 90 degree elbow at the highest point of my panels and installed a brass hose faucet to bleed air out. The interesting part was as i went back through out the day as the pump was running i was able to bleed more an more air out. I can also hear the water running through the 100 feet or so of pvc pipe that goes to my panels. That to me suggests there's a lot of air getting and staying in there. Where is it coming from?
 

Slippery

Active member
Jul 15, 2018
27
Portland or
Am I correct in understanding you already have a vacuum release valve on the solar system? I.e it allows air into the system so that's water can drain when the pump is off? This is an example of one: Amazon.com: HELIOCOL 3/4" New Vacuum Relief Valve Pool Solar Panels - New White: Garden & Outdoor

If so, it should be able to bleed the air from the system as well IF it's properly installed. The relief valve needs to be at the highest point of the system and placed so that as water fills the panels (from bottom to top), air is bled slowly through the valve. Once water hits it, the valve is pushed closed.

Pictures of your setup will help a lot.
this is brilliant! if it can also automatically let air out i'll try one.
 

ashtonfitzgerald

Well-known member
Sep 27, 2016
207
Oshawa, ON, Canada
I ended up creating a 90 degree elbow at the highest point of my panels and installed a brass hose faucet to bleed air out. The interesting part was as i went back through out the day as the pump was running i was able to bleed more an more air out. I can also hear the water running through the 100 feet or so of pvc pipe that goes to my panels. That to me suggests there's a lot of air getting and staying in there. Where is it coming from?
Most likely the air is getting in through a leak on the suction side of the pump. If you bypass the solar completely do you see air coming out of the return jets?