Solar powered Pool Pump

JoeHam

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It looks like replacing his 10 year old 240V pool pump might be worthwhile.

My friend is researching VFD 120V pool pumps and then we will size a 120V AIO to run it during the day primarily with solar and add a minimal 48V LiFePO4 battery.

Starting with Pentair for pool pump research.

We did discuss that any solar equipment purchased in Arizona is free from sales tax and the Federal tax credit will also be a help.
 

HackNFly

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It looks like replacing his 10 year old 240V pool pump might be worthwhile.

My friend is researching VFD 120V pool pumps and then we will size a 120V AIO to run it during the day primarily with solar and add a minimal 48V LiFePO4 battery.

Starting with Pentair for pool pump research.

We did discuss that any solar equipment purchased in Arizona is free from sales tax and the Federal tax credit will also be a help.
Does he have to replace it? If it's currently working, he could use it as a backup with pretty minimal PVC rework, should just require a few TEES and 2 check valves. Then a solar only system would run it in the day and should run long enough to keep the pool clean, and would be the most efficient as going from Solar DC->Battery->AC has to incur some losses. This is what I'm going to try, so I'm curious if you can think of any drawbacks.
 

tomy2

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Pool remodel about twelve years ago, new tile and plaster - 3M quartz. They wanted about twenty grand to do the decks, which had some cracks in them. So they textured and coated, cut irregular cut lines to blend in with the cracks, and textured a fake rock coping.
The coping needs to be re-painted/dyed and recoated with acrylic, and the drive hasn't held up as well as the pool deck, but gee, for the couple of grand I spent on the decks and driveway, it has been phenomenal.

looks good, was that a concrete slurry product or more like a paint?
 

A.Justice

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A.Justice

Swears he didn't start that fire.
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Then a solar only system would run it in the day and should run long enough to keep the pool clean, and would be the most efficient as going from Solar DC->Battery->AC has to incur some losses. This is what I'm going to try, so I'm curious if you can think of any drawbacks.
It's pretty common for pools to have multiple pumps for a variety of reasons (waterfalls, grottos, split spas, etc), so I don't see any issues there. Just make sure you use the pump at least once a week or it WILL eventually sieze. No matter how good the pump seal is, it leaks a small amount of chlorinated water back up into the motor windings and controller board over time, and rust is inevitable.

If you don't already, I also always recommend to my customers that they go out to the equipment out once a week or so while they're pool is closed, and flip on the pumps for a few seconds, it can save a lot of potential headaches from siezed shafts on opening day.
 

JoeHam

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Does he have to replace it?

For my buddy it looks like replacing it will allow for a more cost effective 120V AIO unit vs two in tandem to create 240V in order to run the pool pump.

I'm hoping the startup or LRA requirements of a VFD pump will be much easier to satisfy as well.
 

A.Justice

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I'm hoping the startup or LRA requirements of a VFD pump will be much easier to satisfy as well.
If you start on low speed it keeps the inrush current below the max draw on full speed. From there you can ramp the speed up, which also avoids inrush.

I'm not sure which specific units do it, but some start on slow speed by default for just that reason.
 

Browneye

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looks good, was that a concrete slurry product or more like a paint?

It was a slurry type of texture coating, then painted over and acrylic clear. Kind of like cool decking - shoot on then knock down with a trowel.
The pool decking is nearly flawless, have even pressure washed areas under shrubs that get dark from sappy fallout and then dirt, like a black shadow. Otherwise just hose it off every couple of months, easy care.

The texturing is super durable. Almost looks like FixItAll. For all I know that's what it is. The company was Deckrete, they did a lot of resurfacing in the area. I've used that product for other concrete leveling/patching on inside slab on grade floors.
 

WYtreasure

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If you start on low speed it keeps the inrush current below the max draw on full speed. From there you can ramp the speed up, which also avoids inrush.

I'm not sure which specific units do it, but some start on slow speed by default for just that reason.
Would a "Soft-Start" feature or mechanism be what @JoeHam is looking for? I think the inverter would appreciate that.

Is this typical, even on a 20+ year old hot tub or pool? My hot tub starts on low and the inrush is a bit below the max draw on full speed.
Still scratching my head over how to get the inrush current numbers as the motor switches to high speed. 🤷‍♂️
 

A.Justice

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Would a "Soft-Start" feature or mechanism be what @JoeHam is looking for? I think the inverter would appreciate that.

Is this typical, even on a 20+ year old hot tub or pool? My hot tub starts on low and the inrush is a bit below the max draw on full speed.
Still scratching my head over how to get the inrush current numbers as the motor switches to high speed. 🤷‍♂️
I think it's more regular for a hot tub, or spa, to have a multi speed pump than a pool. Most multi-speed pumps that start on low act pretty much like a soft starter already. Switching to high speed from an already spinning and pressured system won't have the surge like it does from a "cold start".
 

HackNFly

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For my buddy it looks like replacing it will allow for a more cost effective 120V AIO unit vs two in tandem to create 240V in order to run the pool pump.

I'm hoping the startup or LRA requirements of a VFD pump will be much easier to satisfy as well.
I guess I just meant it leave the 240V connected. I see in your original post that the goal is to be off-grid, so if the goal is to be completely off grid and not have any grid power, then that wouldn't be ideal, but if they will still have grid power and could just use it on rare occasion then the dual pump could work.

The pump I was referencing before just came in, half the cost of the other one and much more nicely packaged, no broken parts and decent looking PV cables. It's a 1.2 HP pump so should be plenty powerful but will require 4 panels in my case. This system doesn't require any batteries and just runs when there is enough sunshine.

Also for reference, here is a video of the type of dual motor set up I'm referring to, one solar and one AC.


20220421_123422.jpg
 

JoeHam

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Thanks @HackNFly now I understand better what you’re doing.

Great solution but I’ll have to see if he’s up to the plumbing part for a parallel motor setup. I can help him with the solar power part but all this pool stuff is not for me 😎.
 

JoeHam

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Pentair Superflo VS is the 120v unit.

Any wild guess what the startup power requirement would be for a pump like that ?

Trying to figure if a 3kW inverter would handle it or if a 5 kW would be needed.
 

WYtreasure

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Any wild guess what the startup power requirement would be for a pump like that ?

Trying to figure if a 3kW inverter would handle it or if a 5 kW would be needed.
For reference, my old hot tub, 240 VAC, 2.5 HP;
the pumps start on low speed (2 speed motor) and one motor pulls 10 Amps, the other pulls 11 Amps at start.
Pump specs: Amps 10.7/3.0
 

wattmatters

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Some data from my pump in case it is of any use or interest.

My pool pump is a Hayward Maxflo Variable Speed Pump SP2300VS. It's been in place for ~5 years. It replaced an old single speed pump which was on its way out. The old pump used to draw ~1200W.

The chlorinator is an Astral Pool 6 Series. Pool is ~50,000 litres.

Here we are a 230V AC normal supply. I did a pump speed vs AC power draw test one day and charted the results:

Screen Shot 2022-04-22 at 6.10.15 am.png

Note the expected curvilinear (quadratic) relationship between pump speed and pump power.

The normal cycle for this pump is to begin with a 5-min interval operating at maximum speed, before it drops down to the selected all day running speed.

Currently I have my all day operational pump speed set to 1900rpm, which is ~320-330W. It's selected to allow the Dragonfly pool skimmer to operate at its best.

I have learned that the power draw is affected by the salt content of the pool. If the water get diluted, such as happens naturally with time or usually because of big rain events, then the power draw of the chlorinator falls a little. When I add salt it can increase power consumption by between 10-30W depending on how low the salt level was to start with.

Now the way the unit works is even though it runs a start up cycle at maximum speed, it seems to soft start that process, taking its time to build up to that level.

My off-grid AIO inverter (a PIP clone 48V DC, 4kW / 230V AC) manages the start of the pump just fine. I also did a video of that when I first installed the inverter:


And here's a typical day's load profile (yesterday):
Screen Shot 2022-04-22 at 6.35.25 am.png

Can see the spike in the load to start with, then the all day running power until the duty cycle is complete for the day. On most days with reasonable light the pump barely uses the battery.

I have the start and end of the pump duty cycle automated with Home Assistant and use an offset to Sunrise (+2.5 hours) and Sunset (-3.0 hours) for that. In this way the pump will always operate during the best solar hours, plus the duration of the duty cycle matches the season as a longer duty cycle is required in Summer and shorter in Winter. My pump operates all year as we have a mild climate in Winter.

I also have the Home Assistant turn off the pump should battery state of charge fall below a set threshold.

The chart above is via Solar Assistant, and that is integrated with Home Assistant. Solar Assistant will soon also add to the Home Assistant integration all of the inverter control options, which will mean that I can, instead of turning the pump off when SOC is below threshold, choose instead to change the inverter's mode of operation from Solar/Battery/Utility to Utility first mode so the pump can continue to operate from grid power without interruption, while the batteries can recharge from the remaining solar PV.

This might happen when we get multiple days of rain and poor solar PV output. For now I do those changes manually (can do that remotely via my phone or laptop with Solar Assistant). I know for instance that the next few days the weather will be poor, so I may need to keep an eye on that.

I don't like to see my battery SOC drop much - my (SLA) batteries are really there for grid outage backup so I keep them charged and ready for that - running a pool pump is a side gig for which they act as ballast.
 

Browneye

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The pump I was referencing before just came in, half the cost of the other one and much more nicely packaged, no broken parts and decent looking PV cables. It's a 1.2 HP pump so should be plenty powerful but will require 4 panels in my case. This system doesn't require any batteries and just runs when there is enough sunshine.


View attachment 92036


This pump, this link?

Yes, more detailed information please. The link to the installation manual on the product link is invalid.
Truly this pump runs with two 300W solar panels and a controller? No other hardware? And runs when the sun shines?
Seems absolutely ideal.
 

A.Justice

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Any wild guess what the startup power requirement would be for a pump like that ?

Trying to figure if a 3kW inverter would handle it or if a 5 kW would be needed.
My guess...

Its a horse and a half, so running watts would be ~1200. If it starts in low speed and works its way up to high speed you shouldn't see over 1500w used. The 3k SHOULD be okay, but I would make sure it has a return policy just in case.
 

Warpspeed

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A guy in South Australia posed the same problem about a year ago on another Forum.

What he ended up doing was fitting a pulley to the back of the existing induction motor on his pool pump.
There was a small plastic cooling fan there that he removed to be able to do that.
He then used an old tread mill motor he already had to drive the pump through a flat belt.
A single series string of solar panels powered the treadmill motor directly with nothing else required.

The treadmill motor he already had was rather small, only 1/2Hp and it eventually overheated and burned out after a few weeks.
But it worked well while it lasted, so he bought a 2Hp treadmill motor from e-bay which looked massive next to the old one.
That worked even better, and as far as I know is still going strong.
It made a significant difference to his electricity bills too.

On really dull cloudy days when he wanted to clean out the pool, he would slip the belt off, and power the original pump up with grid power.
The pump runs fine in almost no sun, and fine for just pool filtering like that.
But for vacuuming, the pool it needs grid power on really overcast days, but in full sun it does not need any help for doing the same thing.

Enjoy !
 

HackNFly

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This pump, this link?

Yes, more detailed information please. The link to the installation manual on the product link is invalid.
Truly this pump runs with two 300W solar panels and a controller? No other hardware? And runs when the sun shines?
Seems absolutely ideal.
It requires more than 900 watts of panels. So you'll need a 2S2P configuration with 300 watt panels. In the manual they use 6 200 watt panels in 3S2P configuration. The video I linked shows that type of system in action. The chinese company also uses the same type of MPPT controller for well pumps and have the ability to charge up a battery as well. I don't have that version.
 
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