Help with Solar Pump system design? Please!

[Sunking]

I live in central west Texas with no trees and have about 330 sunny days a year.

I am not trying to be a smart A$$ here but coming from a farm family with kin folk all over Oklahoma and TX, none of them have ever used anything electric for well water. Have you thought about a windmill? Your location and application just SCREAMS WIND MILL. It would be far less expensive, more reliable and productive, and works 24 hours a day.

It is old school tech that has worked perfectly for 200 years. You can make repairs with Duct Tape and chewing gum. Where you are at you have gale winds 364 days a year.

[Mike90250]

...
The pump I am talking about is the Sun Pump SDS-Q-135. Here are the specs on it copied from the spec data sheet (http://www.dcpower-systems.com/uploa...ts/22762_2.pdf).

That pump will not pump for your application very long. You need to see the Pump Curve on it.

The max GPM is at 0" of head. The max head will be something 1/2 GPM at 100'

What size is your well pipe ? 3", 5" 6" ?? As you start pumping, the level will drop from 30' , to some point where the pumping slows to what the level is that the well can maintain. There are charts for what size pipe holds how much water.

Does that pump have a low water sensor in it ??

The cheap way is pure solar, and pump to a 500 gallon grond tank. Let that water flow through a pipe to your house, where you have a pressure pump and pressure tank that runs off 120VAC.

If you can't get an above ground tank, you need to either add batteries, or several more pressure tanks that can carry your water needs through to the next patch of sunlight. Batteries are expensive, and you waste a lot of power in them

[jungleexplorer]

Looked at windmills first. First off they are very hard to get and very expensive. I think the cheapest one I found was like $3,500.00 for like 1.5 GPM @ 15 MPH wind speeds. Contrary to popular belief, the wind does not always blow here, but the sun comes up every day. The day the sun does not come up, I don't think I will be worrying about water. LOL! Also, windmills require monthly maintenance. Back in thew day when you had to pull water out of a well with a bucket and the whole family took a bath in the same tub of water, the windmill was a huge improvement. All ranchers around here now use solar systems for their cattle tanks because it is cheaper, more reliable and requires less maintenance then windmills.

[jungleexplorer]

That pump will not pump for your application very long. You need to see the Pump Curve on it.

The max GPM is at 0" of head. The max head will be something 1/2 GPM at 100'

What size is your well pipe ? 3", 5" 6" ?? As you start pumping, the level will drop from 30' , to some point where the pumping slows to what the level is that the well can maintain. There are charts for what size pipe holds how much water.

Does that pump have a low water sensor in it ??

The cheap way is pure solar, and pump to a 500 gallon grond tank. Let that water flow through a pipe to your house, where you have a pressure pump and pressure tank that runs off 120VAC.

If you can't get an above ground tank, you need to either add batteries, or several more pressure tanks that can carry your water needs through to the next patch of sunlight. Batteries are expensive, and you waste a lot of power in them

Not sure what you mean. Here is a chart for the pump.

SDS-Q-135-chart.jpg

[Mike90250]

How many "feet", does it take to pressurize your tank at ground level to 40# of pressure? That's the other problem.


We'll make a pump expert out of you sooner or later. I am surprised at how flat the pump curve is.

[Sunking]

OK let's KISS this pig (KEEP IT SIMPLE STUPID) The pump you reference too draws 130 watts.

For a off-grid solar system you have to design worse case scenario. So answer these two questions and I will do all the work.

• Worse case how many hours per day will the pump run
• Your location.

That is all we need to know

[jungleexplorer]

That pump will not pump for your application very long. You need to see the Pump Curve on it.

The max GPM is at 0" of head. The max head will be something 1/2 GPM at 100'

What size is your well pipe ? 3", 5" 6" ?? As you start pumping, the level will drop from 30' , to some point where the pumping slows to what the level is that the well can maintain. There are charts for what size pipe holds how much water.

Does that pump have a low water sensor in it ??

The cheap way is pure solar, and pump to a 500 gallon grond tank. Let that water flow through a pipe to your house, where you have a pressure pump and pressure tank that runs off 120VAC.

If you can't get an above ground tank, you need to either add batteries, or several more pressure tanks that can carry your water needs through to the next patch of sunlight. Batteries are expensive, and you waste a lot of power in them

My well is an 8" pipe. The well is 100 feet deep. If you measure from the ground surface down to the water it is 30 feet. So that means there is 70 feet of water in the well. It has a production rate (or recuperation rate) of of 4 GPM. So if the pump pumps 4 GPM or less the level of the water in the well should not go down very much at all.

It is my uninformed understanding that even if I put the pump down at 90 feet the effective head is the distance from the surface of the water to the tank. In my case, 30 feet. If I were to do away with the pressure system and install a tank tower of say 20 feet tall, then the head would be 50 feet. This is my understanding. Is this wrong.

[Naptown]

That would be approximately correct yes

[jungleexplorer]

OK let's KISS this pig (KEEP IT SIMPLE STUPID) The pump you reference too draws 130 watts.

For a off-grid solar system you have to design worse case scenario. So answer these two questions and I will do all the work.

• Worse case how many hours per day will the pump run
• Your location.

That is all we need to know

How much water is difficult to determine. I live North of Abilene, TX on a ridge with and unobstructed view of the southern sky. If this were the only well, I would say the worse case scenario would be the max production rate of the well which would be 4 gpm times 24 hours which equals 5760 gallons a day. But the truth is, this well is only a backup well to our primary well. We have a well that is a lot closer to our house, but it has a low recuperation rate and sometimes we run it dry. This well has a 1 HP 240v submersible pump in it with a 50 gallon pressure tank. I have laid pipe and tied both wells together so that they can both feed into the same system. So essentially, our primary well will handle, most of our needs and the secondary well will only pick up the slack.

Anyway, I think I am beating a dead horse here. The answer is obvious that I need to just lay wire and forget going solar. I appreciate you offer to figure this up for me, but in the end that will be a lot of work for you and it will most likely be cost prohibitive for me to go the solar route. The cattle ranchers around here use solar pumps to fill their water tanks and that is what got me thinking about trying to use solar for my needs. This has been a learning experience for me. Thanks for the help.

[Naptown]

That is a practical use but they are only probably pumping during daylight hours. It's the 24/7 and pressurizing that becomes an issue.

[jungleexplorer]

Just called an electric supply house and the cost of running copper is $2,050.00 but the cost of running aluminum is just $730.00. The cost of a 1/2 HP pump with controller is $305.00. I will go with aluminum. $1,035.00 is a lot better then $30,000.00. You try to be eco friendly, but they just make it so expensive. Until alternative energy becomes affordable for the common person, it will just be a rich persons feel good hobby.

Thanks for all the advice and help.

[Mike90250]

Right, aluminun, generic pump and controller, and you can find parts in 5 years. I went through all this 4 years ago.

[Naptown]

Just called an electric supply house and the cost of running copper is $2,050.00 but the cost of running aluminum is just $730.00. The cost of a 1/2 HP pump with controller is $305.00. I will go with aluminum. $1,035.00 is a lot better then $30,000.00. You try to be eco friendly, but they just make it so expensive. Until alternative energy becomes affordable for the common person, it will just be a rich persons feel good hobby.

Thanks for all the advice and help.

Isn't it funny that you come to a solar forum only to be told your project isn't worth doing?
If you were expecting tree hugging fanatics this is the wrong place.

[Sunking]

You try to be eco friendly, but they just make it so expensive.

Don't beat yourself because there is nothing eco friendly about an off-grid battery system. A battery system will never produce more energy than it takes to manufacture the bits and pieces to make the system.

[jungleexplorer]

Isn't it funny that you come to a solar forum only to be told your project isn't worth doing?
If you were expecting tree hugging fanatics this is the wrong place.

Oh, I am not a tree hugger by any stretch of the imagination. I am a conservationist, not an environmentalist. I believe God gave mankind the world to use, but not to abuse. Where as radical environmentalist believe that mankind is an infection that is hurting mother nature and the world would be better off without us. I have cut many of tree down for my use. But I have also planted many trees to replace them. I see trees as being no different then a crop of corn; it just takes many more years for a crop trees to be ready to harvest then it does a crop of corn.

No, my inquiry about a solar pumping system had more to do with economics and self sufficiency then it did about going green. Hey, if I can be eco friendly and save money at the same time, I will do it. I am not rich, so economy wins with me.