Solar Pool Pumping

System

Ok, exasperated at the cost of DC pool pump, cripes I can buy two dual speed AC pool pump motors for the cost of the cheapest DC pump I found.

Game plan now is to keep the AC motor, actually am going to invest in a dual speed, and run from panels. As I only need it to run in sunlight I am assuming I can escape the cost of batteries?????

Do I need a controller to regulate the power coming in from the panels and if so do they make them where I can run AC as need to account for those 3 or 4 days a year when the sun doesn't shine here in AZ.

So many projects, looking to get the most bang for the buck in what I do. Being this is probable my second most gluttonous power scarf, it might be a good place to get my feet wet with and inexpensive pv unit.

Looking at building a arbor over the pumping area and the end of the pool to accommodate the panels.

Thanks,

Sal

BB.

Re: Solar Pool Pumping

Grid Tied Solar with a multi-speed AC pool pump is going to be the best bank for the buck (plus solar hotwater panel for pool heating).

Not going to be cheap though.

-Bill

Brock

Re: Solar Pool Pumping

If you already have a pump, leave it in place and add a second small DC pump. Depending on the size of the pool I would say about 1/4 to 1/8 hp and let it do the circulating and use the big AC pump for cleaning.

System2

Re: Solar Pool Pumping

BB. wrote: »

Grid Tied Solar with a multi-speed AC pool pump is going to be the best bank for the buck (plus solar hotwater panel for pool heating).

Not going to be cheap though.

-Bill

Not much swimming done in the winter months so not so worried about heating the pool. Why a grid tied system and not a stand alone for the pool pump itself eliminating the batters as it only needs to run during the day. I know I will need a small inverter to go from dc to ac. dunno if that is possible.

If I was going to use a small dc pump, for the added expense it would not be that much more to get a 3/4hp dc which is what I need for my pool, that starts at $600 and goes up.

BB.

Re: Solar Pool Pumping

The following is just a paper evaluation to give rough numbers... The details may be off (just took quick guesses on pricing--did not go into a detailed parts list)--but provides a framework for evaluation of costs between systems. Also, using a well pump for pumping pool water may have other issues (pool chemicals, safety, local sanitation laws, etc.--certainly not an area of expertise for me):

As I see it--you have several ways to go:

1. Grid Tied
2. Full Off-Grid w/batteries
3. Something "different"... Lets say a Grundfos well pump...

Lets assume 3/4 HP, 8 hours per day. Assume that it takes 1kW average power to run it...

1kW*8hrs=8kWhrs per day (or $0.80 per day with grid power). And assume that you want to offset that power for 9 months of the year.

8kWhrs * 30 days = 240 kWhrs per month

Phoenix Arizona, assume defaults with PV Watts program.

1kW of panels, toss the lowest 3 months, gives you 122 kWhrs per month (February).

(240kWhr per month/122 kWhrs per month) * 1kW of panels = 1.97 kWatts of solar panels

Assume $8 per watt for GT installed (you may get 30%-50% rebates and credits depending on your location).

$8 * 1,970 watt = $15,760 installed GT system (very rough guess)

$15,760 cost / (20 yrs * 3,185 kWhrs per year for 1.97kW of panels)= $0.25 per kWhr

Of course, if you get lots of rebates and taxes, may need to replace the inverter once in 20 years, etc... You may get down to $0.13 per kWhr or so...

An off-grid system with batteries--same as above, but instead of 0.77 derating factor for GT, use 0.52 for off-grid with batteries...

81kWhrs per month per 1kW of panels (February is minimum month again)--

(240kWhrs / 81 kWhrs) * 1kW of panels = 2.96 kW worth of panels

Assume Off-Grid installed is $15 per Watt:

2,960 watt * $15 per watt = $44,444

Assume will need to replace the batteries at least once in 20 years (10 year life)--guess at $5,000 replacement costs:

($44,444 + $5,000)/(20yr * 3,180 kWhrs per year) = $0.78 per kWhr

And, at least historically, off-grid systems have not been eligible for near as many rebates.

Using a well pump (don't know if it will work--but seems like a neat idea).... A Grundos SQFlex pump costs about $1,800 for a ~1kWatt pump...

Get ~1kWatt of solar panels, $5,000 + $1,800 for pump + $1,000 for panel mounts + $500 wiring/controller?; all for less than $10,000???--I like the Grundfos pump because it will run on DC from solar panels, or from your AC:

Vac: 1x90-240V
Vdc: 30-300V

A very flexible pump... You can start with a minimum amount of solar panels (if you need less pumping), and add more if you need more pumping. Also very efficient on AC power--switch to your AC when the sun is down--no extra converters needed...

Grundfos is a more expensive pumping system--there are other out there that should be less.

Will a well pump work for a swimming pool system? I don't know--Have to check to see if pool chemicals will attack the pump or not. May need to dig/construct a sump next to the pool to drop the pump in...

Looks like a dedicated solar pool pump is competitive vs the Grid Tied system... With GT though--you can share excess summer production with your A/C and other household power requirements.

With dedicated DC solar pump--excess energy is lost during the summer, reducing its return on investment possibilities. And Off-Grid battery just does not make any economic sense at all.

-Bill

PS: There are "DC" motors that use brushes and there are "DC" motors that use electronic controllers (basically AC motors with electronics to commutate the AC for the motor).

"Real" DC Motor (brushed) will work fine on solar panels--but brushes are a wear item that will need replacement (or more) every year or less.

Not many DC servo type systems that will run directly from solar panels (usually need a battery/power supply for source). Selected Grundfos for this example because it has a solar panel friendly MPPT controller that can take solar panels, batteries, or AC power without any change in pump/motor configuration.

System2

Re: Solar Pool Pumping

What do think about this complete system that should be able to be sized for both pumping through a solar hot water panels as well as just filtering during the winter months: http://store.altenergystore.com/Solar-Pool-Heaters-and-Pumps/Solar-Pool-Pumps/Lorentz-Solar-Pool-Pump-with-PS600-Controller/p5827/

You will also need solar panels sized to your load. I have no practical experience with this system, but I am currently researching it. Please reply with any reviews or lessons learned, especially for use in California.

Solar Guppy

Re: Solar Pool Pumping

Lorentz is the only real PV pool pump solution I've seen, your going to need 600-800 watts of PV if you have solar thermal panels to overcome the head needs.

If your doing this to save money, stop now. Even with the best deals on panels and you doing all the installation, it will take more than 10 years to break even and by that time you will be looking for a new pump 1 or 2 times over

Your best solution is the simplest, remove your current pump and put in a new 1/2hp pump ( not just the motor, the whole pump as the vane is based on the HP of the motor ). Pool company's are notorious for over sizing the pumps ... an average pool, even with roof mount solar thermal will be quite happy on 1/2hp

Two speeds give you more flexibility, turn it on high only when needed to help with pool vacs.

Going the 1/2 HP route and timer no more than 4 hours a day winter 8 hours summer will probably cut you bill by more than half

Windsun

Re: Solar Pool Pumping

We never sold the Lorentz pool pumps, but our experience with the submersibles led to our decision to not sell them anymore about 4 years ago.

retrodog

Re: Solar Pool Pumping

Sal_B wrote: »

Ok, exasperated at the cost of DC pool pump, cripes I can buy two dual speed AC pool pump motors for the cost of the cheapest DC pump I found.

Game plan now is to keep the AC motor, actually am going to invest in a dual speed, and run from panels. As I only need it to run in sunlight I am assuming I can escape the cost of batteries?????

Do I need a controller to regulate the power coming in from the panels and if so do they make them where I can run AC as need to account for those 3 or 4 days a year when the sun doesn't shine here in AZ.

So many projects, looking to get the most bang for the buck in what I do. Being this is probable my second most gluttonous power scarf, it might be a good place to get my feet wet with and inexpensive pv unit.

Looking at building a arbor over the pumping area and the end of the pool to accommodate the panels.

Thanks,

Sal

Not sure where you ended up going with this. One thing you might consider is to change out the AC pump to a Pentair Intelliflo version. They cost about $900-$1,200, depending on model, but supposedly run a lot more efficiently than regular single speed motor pumps. I have two friends who have them and they swear by them.

That way you could grid tie your panels and get the most out of them, while potentially cutting your overall electric use down.

I really like the concept of running the pool pump directly off solar panels though. It's got a nice theory behind it (the more sun you get, the more water you need to move). Even though it might not be the optimum way to operate, it would sure feel pretty cool.