I have a grundfos sqflex solar pump installed in my well for a little over a year. It has worked well with occasional use powered by a portable generator. The well is 230' deep. The pump is set at 220'. The water level in the well is 80'. The well's flow rate is 2gpm according to my well driller.
I want to install just enough solar panel to maintain a 2gpm flow into a storage tank when the sun is up. The performance curve of the pump said it will require 300watt at 210ft head. 120watt at 90ft. How much panel do I need? A little over 300w or just under 120watt???? Should I use the depth where the pump was set or the static water level? I don't want to exceed the well's flow rate by providing too much power. Thanks for your help.
What is the flow rate of the well.
If greater than the pump rate then you can use the 80ft level.
Oversize your solar array to allow for line losses.
Go with close to 150 watts of solar panels.
With more specifics about the pump we could give more info.
Got a website that gives details on the pump?
I have a simalar setup except that I have a Dankoff pump. I have installed one just like yours for a neighbor. Warning You can not have too many solar panels. I would put the pump at about 100 or 120 ft and run some where between 200 and 300 watts. I have 240 watts on mine. They make some special panels for those Grunflos that are 66volt panels. If I remember those pumps can run on just about any thing AC/DC from about 12v to 300 volts. The 66 volt work really good if you can find them. Other wise I would probably go with four panels running 48 volts. I have 4 12 volt in series for 48 volts on mine. It pumps about 2 1/2 gallons a min. Warning again it is far better to pump into a storage tank than into a pressure tank. If you pump into a pressure tank you have to consider the pressure as part of the lift requirement.
Attempting to control the rate of pumping by panel wattage will not work. the pump will either pump or it will not. If you go light on the panels it just means that it will take more sunlight to pump than it does with more panels. Thus if your panels are marginal it may only pump from 11 Am till about 2 or 3 PM. With more panels it will start pumping at 9 or 10 and pump untill 4 or 5 depending on where you live. Going small also means that if it is a cloudy day and not much sun you may not pump at all. I guarantee if you run out of water it will always be at night and if your panels are too small and its a cloudy day you may not get any water the next day. It appears that you have a generator for those times, But the purpose of solar is to not use the generator.
Thanks Pooh Bear. The pump is Grundfos SQflex 11 SQF-2 Helical Rotor. The flow rate of the well is 2gpm according to well driller. I think it might be much higher because I can pump with full power with generator power (11 gpm) and the well didn't go dry yet. So, if I plan for 2gpm, it should be safe to not over pumping.
My main question was how to read/determine the meaning of head? Does it go by how deep the pump was set or the water level?
Thanks Jim. I agree with you that it's nearly impossible to control the flow rate with the exact amount of solar panel. The pump already set by the well driller at 220ft. I don't know enough and don't want to mess with it.
This pump can take a wide range of voltage and current. The flow rate is up to 11gpm. The more power, the higher flow rate up to the pump's maximum. With less power, it will pump .1gpm with as low as 40watt at 90ft head. Do I really need to pull the pump up higher to conserve power?
There is 3 types of head (regarding pumps).
Suction Head = the distance from the pump to the water surface.
Since you have a submersible pump this figure is irrelevant.
Lift Head = the total vertical distance from the water surface
to the discharge point of the pipe. In your case meaning the
distance from the water surface to the height you are pumping it to.
Total Head = Suction Head + Lift Head.
Your suction head is essentially zero so you only need Lift Head.
So use the vertical distance from the top water level in your well
to the highest point you will be pumping water.
You are forgetting the storage capacity of the well. I.E. a 6" well has 1.47 gal/foot of water in it. If the pump is sized to pump from the depth it is set at in the well, you can plan on using all the water above the pump inlet. If not, then the pump will draw down the well to the level the pump can't move water from.
All the while the pump is moving water up to the house, the well is recovering at the 2 gpm. So you probably have much more water available than a house is going to use unless you use more water than 2 gpm for hours at a time.
That's why you need to know the refresh rate of the well.
If you are pumping 2gpm but the well is only flowing at 1gpm
eventually you will pump it dry if you don't give it time to refresh.
And also you would need to use the lowest point of the draw
down level for head calculations.
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The Wells flow rate is 2gpm according to my well driller.
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From the original post. If the fellow has a large pressure tank and keeps his pump rate at under the 2 GPM he should be able to use the static water level as a very good guide.
We spent many years living with a flow rate of 2gpm for a family of four. [img]/forums/images/icons/grin.gif[/img]
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