Considering Solar for Surface Well Pump

fellixx

Hello,

I am new to the whole topic of solar power but recently I have taken a hard look at my utility bill and I have starting looking at ways I can reduce it. Most of my major appliances are now fairly new with the exception of one very important item which is my 3/4HP well pump. This pump runs off of 240V and runs quite often to a point that I know without ever looking at the meter that it costs a lot to run it. (Hence my post here)

It only took a few Google searches to figure out that solar powered water pumping systems are out there in various forms but aside from the fact that it seems that these systems are mostly installed in remote locations it seems as if most if not all of them are for submersible pump systems combined with over sized storage tanks. I haven’t seen any publications regarding single family homes using solar power to drive surface well pumps. So to sum it all up, here are some questions I would like to pose to all of you to see if I should even consider this type of system for our household;

1. Using my existing 3/4HP well pump and pressure tank, can solar power be utilized and still maintain existing pressure? Would I have to replace one or both components?

2. Even living in sunny West Palm Beach it does rain here quite often. I was thinking of possibly running a direct powered system that was augmented by grid power. Is this even possible and does it make for a more complex and expensive system?

3. In this type of application would it still make sense to consider using batteries? My thought here is that since energy consumption is generally at its lowest when power generation for solar is at its highest it would seem to make sense to "store" the energy that’s captured for later use. I would imagine that power output would be greater as well.

4. What’s the ballpark figure for such a system? I realize I have not given absolutely all the factors for designing a system but I am just trying to get a guestimate as to what this could potentially cost.

I apologize in advance if this subject has already been addressed elsewhere but if you could possibly post the link to the article I would greatly appreciate it.

Thanks,

Fellixx

GreenPowerManiac

Re: Considering Solar for Surface Well Pump

Wow ! You're looking at an expensive setup for Solar. Many systems out there are set up for 120v A/C with low load. A 240v pump is one of the most difficult things to start using Solar powered anything, especially 240 volts.

On my home, my system is the same, 240 volts. It draws up to 40-50 amps surge and runs for a minute or two on a 20 amp breaker. This requires a 240 volt Inverter in phase. Two 120v power sources in phase output. My 15 deep-cycle battery bank can't take this kind of surge & I'm running a combined 3kw system. A 10kw system would work OK, but who has the $$ ?

Might want to consider saving money by running lights or solid-state electronics, or quite frankly, your garage items at 120v. I spent $6400 building my own system with wind and solar for a combined output of 3kw.

Nowadays, the push to go Green is ever increasing, & highly overrated. A small system of 2kw will not run the entire house, but it will save 10-20 dollars a month with your utility bill.

Cariboocoot

Re: Considering Solar for Surface Well Pump

If you're looking to reduce your utility bills, conservation will give you a better return per $ spent than anything else.

Solar electric is expensive. It won't save you a nickel on your electric bill if you include the capital outlay costs. An off-grid system produces at an annualized rate of $1 - $2 per kilowatt hour. Grid-tie can be half that or less, depending on how willing your local utility is to buy back surplus power and what government incentives you can take advantage of to off-set the initial costs.

Trying to run a 3/4 HP well pump off solar is murder. That's a very large power requirement. It is not, as many would assume "746 Watts (1 electrical horsepower) * 0.75". It's more like 1350 Watts running, plus a big start-up load (3-7 times running current). I can't give you an exact number, because motors and pumps vary, and then the application they're in will change the way they draw (i.e. amount of lift or available head, flow rate, pressure ...)

You say your pump runs quite often. Why? Large water usage? look at conserving there. If it is 'cycling' a lot it may be due to an undersized pressure tank. Better to have the pump come on and fill up a really big tank once or twice a day than fill a too small one seven or eight times.

As for changing for a different, 'direct from solar' pump or such it is impossible to say whether or not that is viable without knowing the water set-up. At a guess, a 3/4 HP 240 VAC pump is probably on the 'deep' side; this could be a 'shallow' well running at 50-80 feet, or it could be a submersible pump 150 feet down.

Take a look at the prices on some of the heftier pumps at NAWS:
http://store.solar-electric.com/sun-pumps.html
http://store.solar-electric.com/grsoposuwapu.html

How much capital do you want to spend? You'd probably be better off starting with a Kill-A-Watt meter (around $30) and seeing what sort of 'energy hogs' you can track down in your house.

But be warned: one of them may be your wife or kid!

sawmill

Re: Considering Solar for Surface Well Pump

Would it be possible to go with a 1/2 hp pump rather than the 3/4? This would offer savings before thinking of solar.

As suggested a larger pressure tank would save on pump cycles and would save electricity no matter what hp pump is being used.

BB.

Re: Considering Solar for Surface Well Pump

Talk with a pump supplier and see what they would recommend to increase your system efficiency...

Some pumps can be run off of solar or AC power (Grundfos is one brand)--so you can put the pump in well, connect with AC for now--and have the option of solar at a later date (direct or battery backed).

In reality--you should look at your kWhr per month/year usage and costs--vs the capital cost of installing a new pump and capital costs / xx years of expected life vs electricity saved).

If you have a need for water when the power is out (2 weeks after a hurricane for example)--an energy efficient pump, sized for your needs, is cheaper to run off a back up genset (smaller motor, less fuel used), or to install on solar.

In the end, conservation, as others have said here, is almost always cheaper than throwing solar panels at something (and adding batteries for night/cloudy weather operation) will make a power system 2-4+ times more expensive (battery costs, replacement, charge controller, more panels because of battery+charger losses, etc.).

-Bill

fellixx

Re: Considering Solar for Surface Well Pump

Cariboocoot wrote: »

If you're looking to reduce your utility bills, conservation will give you a better return per $ spent than anything else.

Solar electric is expensive. It won't save you a nickel on your electric bill if you include the capital outlay costs. An off-grid system produces at an annualized rate of $1 - $2 per kilowatt hour. Grid-tie can be half that or less, depending on how willing your local utility is to buy back surplus power and what government incentives you can take advantage of to off-set the initial costs.

Trying to run a 3/4 HP well pump off solar is murder. That's a very large power requirement. It is not, as many would assume "746 Watts (1 electrical horsepower) * 0.75". It's more like 1350 Watts running, plus a big start-up load (3-7 times running current). I can't give you an exact number, because motors and pumps vary, and then the application they're in will change the way they draw (i.e. amount of lift or available head, flow rate, pressure ...)

You say your pump runs quite often. Why? Large water usage? look at conserving there. If it is 'cycling' a lot it may be due to an undersized pressure tank. Better to have the pump come on and fill up a really big tank once or twice a day than fill a too small one seven or eight times.

As for changing for a different, 'direct from solar' pump or such it is impossible to say whether or not that is viable without knowing the water set-up. At a guess, a 3/4 HP 240 VAC pump is probably on the 'deep' side; this could be a 'shallow' well running at 50-80 feet, or it could be a submersible pump 150 feet down.

Take a look at the prices on some of the heftier pumps at NAWS:
http://store.solar-electric.com/sun-pumps.html
http://store.solar-electric.com/grsoposuwapu.html

How much capital do you want to spend? You'd probably be better off starting with a Kill-A-Watt meter (around $30) and seeing what sort of 'energy hogs' you can track down in your house.

But be warned: one of them may be your wife or kid!

I beleive it is an undersized preasure tank which I am addressing which is also another reason the solar conversation came up. The pump isnt short cycling but I can guarentee that for every time a tap is turned on in the house, the pump turns on. As for the depth of the actual well, the water table in south Forida is minimal. My well for instance is around 18 to 20ft deep. The actual well head is relatively close to the house as well (<100ft).

As for how much Im willing to spend, thats debatable but as I read up on how solar technology has advanced over the years, Im figuring it maybe worth looking into now. Especially now as I am getting ready to replace my preasure tank and possibly the pump as well since both are getting quite dated.

Fellixx

fellixx

Re: Considering Solar for Surface Well Pump

sawmill wrote: »

Would it be possible to go with a 1/2 hp pump rather than the 3/4? This would offer savings before thinking of solar.

As suggested a larger pressure tank would save on pump cycles and would save electricity no matter what hp pump is being used.

I wondered about this as well. The well is not deep. (18 to 20ft) which makes me wonder why so large of a pump was used at all. Its a single story 3 bedroom home with two full bathrooms. To me a pump that size would be overkill. That is of course, if a water softener and iron filter ( I have both) warrant that size of a pump.

fellixx

Re: Considering Solar for Surface Well Pump

BB. wrote: »

Talk with a pump supplier and see what they would recommend to increase your system efficiency...

Some pumps can be run off of solar or AC power (Grundfos is one brand)--so you can put the pump in well, connect with AC for now--and have the option of solar at a later date (direct or battery backed).

In reality--you should look at your kWhr per month/year usage and costs--vs the capital cost of installing a new pump and capital costs / xx years of expected life vs electricity saved).

If you have a need for water when the power is out (2 weeks after a hurricane for example)--an energy efficient pump, sized for your needs, is cheaper to run off a back up genset (smaller motor, less fuel used), or to install on solar.

In the and, conservation, as others have said here, is almost always cheaper than throwing solar panels at something (and adding batteries for night/cloudy weather operation) will make a power system 2-4+ times more expensive (battery costs, replacement, charge controller, more panels because of battery+charger losses, etc.).

-Bill

Outages arent really of a concern. I have a generator and transfer switch which allows me to drive the pump during significant outages.

Cariboocoot

Re: Considering Solar for Surface Well Pump

If the pump comes on every time someone opens a tap, that is 'cycling'. Either you have one of those ridiculous 5 gallon PT's or the one you have has become 'water logged' or suffered some other failure (low air pressure in the bladder, terminal weeping through a fitting).

Also, with a 20 foot deep well you don't really need more than a 1/2HP 'standard' pump.

Lefty Wright

Re: Considering Solar for Surface Well Pump

I agree with others that changing over to solar power for your well pump may not be the best way to lower power bills. But you can save a lot of electricity by looking over your pump and pressure tank situation.

My static water level is at 200 feet and my 3 wire 3/4 HP pump draws 9A after it's initial surge. Since I pump into a large storage tank I don't run the pump every day. A small booster pump fills my pressure tank.

This doesn't require very much power.

Have you checked to see if your pressure tank has become waterlogged? That would cut your storage capacity and cause your well pump to run too often.

fellixx

Re: Considering Solar for Surface Well Pump

Cariboocoot wrote: »

If the pump comes on every time someone opens a tap, that is 'cycling'. Either you have one of those ridiculous 5 gallon PT's or the one you have has become 'water logged' or suffered some other failure (low air pressure in the bladder, terminal weeping through a fitting).

Also, with a 20 foot deep well you don't really need more than a 1/2HP 'standard' pump.

Not a ridiculous 5 but instead a pathetic 6 gallon tank. Everything I’m reading says that way too small a tank. The question for me again comes back to how big of a tank should I consider as a replacement? I’m thinking a 40 gal tank. Also something else that Im considering is that the motor I have is dual voltage capable. I’m running 230V now but it’s capable of running at 115. I’m trying to see what the disadvantage would be to converting it to the lower one. (Yes I know it’s not as simple as hitting a switch). The docs on the pump does not show a difference in spec if you decide on 115V. BTW its a Sta Rite SND series pump.

Thoughts anyone?

BB.

Re: Considering Solar for Surface Well Pump

If you can run the pump at 230 VAC--keep it at that voltage... Wiring for 115 VAC will just double the current and increase losses (and increase required wiring/breaker size).

-Bill

Cariboocoot

Re: Considering Solar for Surface Well Pump

Get the biggest pressure tank you've got space for and can afford to buy: cutting down on pump cycles saves energy and lengthens the life of the pump.

Bill is, as usual, correct: switching the pump to lower voltage will use more energy, not less.

But switching to a smaller pump might be advantageous, if yours is ready for replacement.

fellixx

Re: Considering Solar for Surface Well Pump

Yea been thinking about the pump......not sure its ready for replacement just yet and given whats been said about efficiency of 230V vs 115V I cant honestly justify its replacment just yet. I did however figure out the sizing for a potential tank and it looks like I can get a 40Gal tank that has the same footprint as my 6gal tank. BUT, as I was doing the measurements and recording model and serial numbers I noticed some dripping comming from the preasure switch which is a 30/50 switch that came with the pump. Guess Ill have to look at potentially replacing that. It just never ends.

BTW thank you all very much for your help with thinking all this through. It has truly been an educational conversation. though I have to say I am not feeling much love for the company that installed this system for this house.

fellixx