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taking the pool pump solar powered

tchendrix

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Jul 21, 2022
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I've been doing some rough calculations and the pool pump is killing me. Here's the info I've got:

pool pump:
brand: Century, 1.5HP
volts: 230/115
amps 7.2A/14.4A

chlorine cell:
brand: Solaxx
input volts: 120/240
input amps: 1.8A/0.9A
output volts: 30vDC
output amps: 6A

desired results:
charge during the day (4-6 hours usable sun in this location
battery configuration: lifepo4 (minimum ah to achieve goal)
I want to run the pump and salt cell off the battery at night for 10 hours

If I go strictly off of aH I think that is 14.4A + 1.8A + 6A = 22.2 aH running for 10 hours for a total of 222 aH. So I'm guessing a 280aH battery bank would work using EVE cells.


Is this right? If so what equipment would I need to take this thing solar? I'm guessing a single 400 watt panel would get me the 9/10 hours off of the battery at night?

what would I need as far as battery, bms, inverter, panel (what else) to accomplish this?

thanks
 
chlorine cell:
brand: Solaxx
input volts: 120/240
input amps: 1.8A/0.9A
output volts: 30vDC
output amps: 6A


'chlorine cell' What is 'chlorine cell'? What is this unit? It looks to be power supply.
 
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chlorine cell:
brand: Solaxx
input volts: 120/240
input amps: 1.8A/0.9A
output volts: 30vDC
output amps: 6A


'chlorine cell' What is 'chlorine cell'? What is this unit?
it's a salt water pool so the cell splits the chlorine off of the salt to sanitize the pool
 
If I go strictly off of aH I think that is 14.4A + 1.8A + 6A = 22.2 aH running for 10 hours for a total of 222 aH. So I'm guessing a 280aH battery bank would work using EVE cells.


Is this right? If so what equipment would I need to take this thing solar? I'm guessing a single 400 watt panel would get me the 9/10 hours off of the battery at night?
If only it were that easy.

You have to get things to the same units. In this case KWH's

On the AC side you've got 22.2 A x 120V = 2,664 watts x 10 hrs = ~27KWH of usage

On the DC side that 400 panel will average around ~2.5 KWH's per day generation and that's before any losses in charge efficiency and conversion from DC to AC.

I hope that helped a bit. It's my bedtime.
 
It is not 22.2 ac Amp, the 6 dc Amp should not be factored in, the 6A is the dc Amp on the output side of that power supply that takes in 120Vac @1.8A then convert to 30VDC @6A.
 
Pool pump power consumption: 230 V x 7.2 A = 1656 W
Chlorinator power consumption: 120 V x 1.8 A = 216 W

Total power consumption 1872 W ~= 1.9 kW.

Must be a bloody big pool to need that much pumping and chlorination power. Or those are peak power readings and they don’t actually draw that much power most of the time.

10 hours at 1.9 kW = 19 kWh

At minimum you would need a 5 kW PV array, and 40 kWh of battery storage.

Why run at night? Run it during the day when the energy is actually generated. Don’t need anywhere as much battery then.

Do an actual energy audit on your pool operation. Find out how much power it actually uses. Only then can you scope a PV system suitable for its operation.
 
I agree with running during the day rather than storing power for night, if operating off-grid.

Is grid-tie net-metering an option?
How about grid-tie zero export?

Not mentioned yet is that your 1771 W rated pump will need 8855 W surge to start it. So you would need an inverter able to deliver that for about a second.
Easier to let the grid start it, and have GT PV inverter backfeed the grid or at least the house, and offset consumption.
 
It is not 22.2 ac Amp, the 6 dc Amp should not be factored in, the 6A is the dc Amp on the output side of that power supply that takes in 120Vac @1.8A then convert to 30VDC @6A.
Yep. The only point I was trying to make was there is no way the OP is going to run that set up with one 400 watt panel and that there was lot more that had to go into to the design.
 
The pump consumption will be continuous. We have a 0.75HP pump and it uses about 800W when running at full speed.

It's well worth considering a pump speed controller, ours now consumes about 440W while still giving adequate circulation. However, you do need to work out the flow rate that you actually need and if a reduced flow rate will work. (It seems that pool pumps are usually over sized.)

A speed controller should soft start the pump as well, reducing any starting surge.

Agrre with using the energy directly during the day as well.
 
While operating time is a bit shorter at this time of year, my pump and chlorinator today drew 1.6 kWh. In Summer it’ll be more like 2.2 kWh.

It runs on ~320 W. 50,000 liter pool.
 
Here is what I’m thinking for my pool pump. Similar watts (1650) as OP, but no salt chlorinator. Going to run 4 - 400w panels with microinverters wired into the load side of the pump timer which is set to run from 8am to 8pm. Risk is zero that I would ever have surplus to go back to grid, not going through a net metering agreement, way to expensive. If there is a surplus from these i know the rest of the circuits in the house will consume it.
 
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I agree with running during the day rather than storing power for night, if operating off-grid.
I also agree.
Not mentioned yet is that your 1771 W rated pump will need 8855 W surge to start it.
It could be more than that too. OP should absolutely get a clamp ammeter with inrush feature to find out. Inrush on pool pumps can be absurd.
 
Inverter pump like intelliflo will use 1/3 to 1/4 the power of a regular pool pump.
Chlorine generator doesn't run 24/7 except during "shock".
Mine runs 100% duty cycle but only 8 hours a day when the pump is running.
Get a gpm meter, they make venturi ones that strap over a small hole in 2" pvc pipe.
Only need one turnover per day for effective filtration. You can do this with a lot of movement during the day, or with low flo 24/7.
If you have a heater it may require a minimum flow rate, none of your other equipment is likely to care. Well chlorine gen has a flow switch, it should be fine at lower flows.
 
One offbeat and really simple way to do a solar pool pump is to use a dc treadmill motor, and couple it to the grid driven pool pump with a drive belt.

Then power the treadmill motor direct from a series string of solar panels.
No battery, no inverter, no control system of any kind.

It will run slow on cloudy days, but it will still run.
Power to drive the pump goes up cubed law, so a big reduction in solar does not slow the rpm as much as you might expect.
Also there is no massive starting surge, it starts to creep at sunrise, and just goes faster and faster as the sun comes up.

If you need full flat out power, for example pool cleaning on a really cloudy day, just fire up the original pump motor off the grid.
This is not armchair speculation, it has been done, and is proven to work really well.
 
Maitake has the right path to take, I just would not focus on turn over or super long run times, they don't really matter in residential pools.
Change it out for a variable speed pump and save energy all the time. If you decide to change the pump, make sure you have the right impeller setup to ensure you get the flow needed. Putting a variable speed unit on the wrong impeller won't be nearly as efficient.
You just need enough flow for effective skimming and chlorinating, you don't need to worry about turnover in a resi pool. You will be shocked at how effective low RPM operation can be in a matched impeller/pump system.
 
Our pool pumps were one of the first things targeted for solar, as the power use was costly.
I run the pumps during the day, powered directly off the PV panels, through the inverters.
I have the pump timers set to run during max insolation time of day.
When clouds block the Sun, the inverters temporarily borrow power from the grid.

Each pump uses 1500 watts, so I needed 3kW continuous, just for the pool.
(The heat pump & other loads also are solar powered)

There is a manual transfer switch that can be used to switch the pool pumps between solar and grid, as needed for special situations.
pool_pump_transfer_switch copy.jpg
I have FLA batteries, not designed for heavy cycling like the Lithiums are, so my batteries are in "standby" mode.

Screen Shot 2022-07-23 at 14.15.25 copy.png
 
Here is what I’m thinking for my pool pump. Similar watts (1650) as OP, but no salt chlorinator. Going to run 4 - 400w panels with microinverters wired into the load side of the pump timer which is set to run from 8am to 8pm. Risk is zero that I would ever have surplus to go back to grid, not going through a net metering agreement, way to expensive. If there is a surplus from these i know the rest of the circuits in the house will consume it.

"Guerrilla Solar"

If the pump has a thermal switch, might be best to wire in after that.

You can get PV string inverters of old models, new or used. Simplest and cheapest way to power the pump.

The pump consumption will be continuous. We have a 0.75HP pump and it uses about 800W when running at full speed.

It's well worth considering a pump speed controller, ours now consumes about 440W while still giving adequate circulation. However, you do need to work out the flow rate that you actually need and if a reduced flow rate will work. (It seems that pool pumps are usually over sized.)

A speed controller should soft start the pump as well, reducing any starting surge.

Agrre with using the energy directly during the day as well.

Do you have a speed controller on a single-speed split-phase motor?
I've seen controllers for soft-start and variable speed, but they said not to operate continuously below 80%.

I first switched to a 2-speed motor, but half speed was insufficient. I then installed a VFD and 3-phase motor, which starts very soft and will run any speed. It's poor power factor (only draws current from peak of sine wave) is a problem for my GT PV inverters when operating off-grid, which apparently see distorted AC waveform. Works with my (large) battery inverters.

What would be desired is a VFD that varies speed to use available power (Grudfos does that with well pumps). Don't know if such controllers are readily available stand-alone but I have seen listings before. I have no idea whether these are any good:

https://www.ebay.com/itm/185412718668

There are variable speed consumer pool pumps now. More expensive, of course, and controller integrated into motor package. They have extra features like detecting something (someone) stuck on water inlet and shut off. But wouldn't have the feature of PV input.
 
Got a DC pool pump motor?

You're right it would be simple. And some brushless DC do that. I run fans that way, off a couple solar panels.

If the $200 photovoltaic VFD is good, that's reasonably economical. But 3-phase pool pump motors don't come cheap.
 
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