Pump settings for solar

Sep 29, 2015
100
Las vegas nv
Just had my solar installed and trying to find the best settings for my pump. Pool is 10k gallons, single story house, sun trek solar system. Feed pipe goes up about 14' then over about 32' on the roof, back through 28' of panels, 10' of return then straight down about 14'. My usual pump setting for my Hayward ecostar VS pump is 50%. I have it split 50/50 between skimmer and vacuum. With this setting he vacuum moves good and water circulates good as well. Pressure on filter reads 4psi. If I leave it on 50% and turn solar on the pressure increases to 7psi, vacuum moves very very slow and water circulates very slow. You can watch the water flow through check valve so I know it's coming back just much slower. If I turn the pump to 75% the pressure is about 14psi. 100% and pressure is around 30%. What would be the best way to take full advantage of my new solar setup? 30 psi seems high especially to run for several hours a day.
 
How many solar panels do you have? You want to send about 1 gallon per minute per 10 square feet of solar panel. If you do not have a very large bank of panels then you probably need to divert some of the flow and bypass the solar or keep the pump speed down a little bit.

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How many solar panels do you have? You want to send about 1 gallon per minute per 10 square feet of solar panel. If you do not have a very large bank of panels then you probably need to divert some of the flow and bypass the solar or keep the pump speed down a little bit.

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How do I determine the amount of water flowing at certain pump speeds?
 
I knew I should have never said that :). There is no easy way. Go up and feel the panel's if they're cool then you have enough water flowing through them if they're warm you need more water flowing through them. But you don't want to have too much water flowing through them because that will pressurize them and could damage the panels.
 
I knew I should have never said that :). There is no easy way. Go up and feel the panel's if they're cool then you have enough water flowing through them if they're warm you need more water flowing through them. But you don't want to have too much water flowing through them because that will pressurize them and could damage the panels.

I get what your saying. My main concern is running the solar with the vacuum still cleaning. We're supposed to get 80 degree temps this weekend so I'll get up there and feel them. My thinking is that I might have to run 75% with the solar getting 50% of the water and maybe the vacuum will run as it should.
 
It is a bit of trial and error. If at the low speed with 100% going to the solar you are not getting good cleaning, then you may need to increase the pump speed and reduce the % of water going to solar to get more flow to the cleaner.
 
That sounds like a lot of back pressure building which can lead to solar panel failure, can you post pictures of your installation something may be off. To check to see how much pressure the panels are actually seeing, you may wish to temporarily T in a pressure gauge with the vacuum release valve at the panels, ideally you want less than 5 psi at the panels, if you have more than that you should look at down stream restricitons, like eyeball fitting size, and move up a size..
 
That sounds like a lot of back pressure building which can lead to solar panel failure, can you post pictures of your installation something may be off. To check to see how much pressure the panels are actually seeing, you may wish to temporarily T in a pressure gauge with the vacuum release valve at the panels, ideally you want less than 5 psi at the panels, if you have more than that you should look at down stream restricitons, like eyeball fitting size, and move up a size..
Here are a couple from when the install was in progress. 2" pipe for everything.

Not best pics but maybe you get an idea
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Yeah, that is not a very large solar bank and those 20' long panels provide a lot of added restriction. So you should not try to force too much water through them.

Can you draw up how they are plumbed? Are the fed and return from the bottom of the 2 headers (not ideal), or is the return coming out of the top of the right header (not in the picture)?

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Something looks wrong with that roof top plumbing, but it is hard to tell from that angle and without seeing the other end. Are they being fed corner to corner and bottom to top, if not you may have an issue with air being trapped in the panel.
 
Something looks wrong with that roof top plumbing, but it is hard to tell from that angle and without seeing the other end. Are they being fed corner to corner and bottom to top, if not you may have an issue with air being trapped in the panel.

I'll edit my signature when I have computer access, I'm mobile now. Yes it is feeding bottom right corner and returning bottom left corner then back up to run down side wall. I think I get what your saying. I could possibly have say the top two panels just filled with air and being compressed so instead of water flowing through all five panels then maybe only three and increasing pressure?
 
Another question, would it be ok that the return will go from the top left corner down maybe 2' and then over and down the wall or should the return pipe run the length of the side collector then U-turn back up and over? or that wouldn't really matter since it will be corner to corner either way?
 
The first option so it is easier to get the air out. Do you have a Vacuum Release Valve (VRV)? Where is it?

Honestly, the blue line should never go so high up the roof. It should be all down hill from the panel so that the panels can drain when the pump is off. Leaving water in the panel in the sun with the pump off, can weaken the panel plastic and damage them.
 
The first option so it is easier to get the air out. Do you have a Vacuum Release Valve (VRV)? Where is it?

Honestly, the blue line should never go so high up the rook. It should be all down hill from the panel so that the panels can drain when the pump is off. Leaving water in the panel in the sun with the pump off, can weaken the panel plastic and damage them.

VR is on top right. So it would be best to have pipes run horizontal along wall and then up and over the eave?
 
I agree with Jason, it would be better if the cold feed line were to go straight tot the edge of the roof then down below the eave, otherwise the middle option looks good. As to the VRV it may work ok for you where it is, however if you find it starts sucking air while the panel is in operation you may need to move it to either bottom corner. This is one of those theory vs practice things, as sometimes the VRV needs a little positive pressure to stay closed, also sometimes you will have slight negative pressure at the top of the panels due to siphon effect depending on the resistance in your hot side check valve.

Ike

p.s. if it were me I would check for trapped water in the panel when I moved the hot return from bottom left to top left before moving the cold feed line as it may have enough siphon effect to drain the panels or it may not, depending on pump pressure and if you used a solar valve or a regular diverter, if a regular diverter you may need to drill a pin hole in it to allow draining, or add a bypass bridge between the hot and cold side with a valve in it. On my solar install I used a 1/2 inch PVC bridge between the hot and cold feed near ground level with cut off valve on it that keep at just a trickle of bypass flow along with a drain valve.

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Equipment is indoors behind that wall, note wire tying the drain valve closed, shortly after I installed my solar heater a small limb from a pine tree fell and bumped the drain open, so now it is tied shut Note also the light blue teflon tape and screw in plug that can be used to blow out the panels with air in the winter
 
If I leave it on 50% and turn solar on the pressure increases to 7psi, vacuum moves very very slow and water circulates very slow. You can watch the water flow through check valve so I know it's coming back just much slower.
7 PSI at the filter, you may be loosing prime in the panels because the VRV is opening. Do you see any air coming down through the check valve? If so, you just need to increase the RPM.
 

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