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Solar for my pool pump

NaterPotaiter

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Joined
Feb 10, 2021
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Hi guys, hoping you can give me some advice. I need to build a cover for my pool pump so it's not getting baked by the sun. I'm curious what it would take to build it a little solar roof? I live near Santan solar so I can easily run down there and grab some of those $50 panels Will loves. But what would it entail to actually run the pool pump off of solar? Would it be easier to build an off-grid battery system or grid-tie it? I'm guessing both options will be pretty costly and probably not worth it, but still thought I would ask. And I did build my own lithium battery system for my camper but please still talk to me like I know nothing. I've seen this question asked before but I didn't really understand what would be needed to run off of solar. And I live in AZ if anyone knows what it takes to grid-tie a small system like that here. Thanks guys.
 
But what would it entail to actually run the pool pump off of solar?
What pump? Gotta have usage numbers to estimate solar numbers.
Volts, amps, surge amps, number of hours per day...

Would it be easier to build an off-grid battery system or grid-tie it?
Easier? Have you determined what permitting will entail? I think the $50 Santan panels
have info scrubbed off which makes them un-permitable.
 
I just did my well and pool pump with the used Santan panels and a Growatt all in one via a sub-panel off-grid. Cheap easy, very straightforward. Set the pool, which runs at 500w, to run 8 hours a day when solar is available. Made a 24v50ah bat from some used Lifepo4. A fun project that all-in costs around 2k.
 
I just did my well and pool pump with the used Santan panels and a Growatt all in one via a sub-panel off-grid. Cheap easy, very straightforward. Set the pool, which runs at 500w, to run 8 hours a day when solar is available. Made a 24v50ah bat from some used Lifepo4. A fun project that all-in costs around 2k.
Can you share your design and list of eqpt? Thanks.
 
I've never done it but seems to me if you only need it to run during daylight hours you don't even need a battery!
Just match the panels to the pump's draw (and startup peak) and let the sun turn it on and off.
Do you even need a charge controller or timer?
 
10 used(cracked backing) panels from Santan(35 each+delivery), 24v Growat LVM eBay(689), LifePo4 came from the company with the ape logo? can't think of the name. Subpanel with breakers Amazon(35). Panel brackets Aliexpress (5 a set). For large wire, I chopped up an old set of jumper cables and was able to snag some leftover pv wire from a neighbor. Pic below shows some normal usage, the spikes are the well filling the pressure tank and the 500w in the middle is the pool pump.
 

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I've never done it but seems to me if you only need it to run during daylight hours you don't even need a battery!
Just match the panels to the pump's draw (and startup peak) and let the sun turn it on and off.
Do you even need a charge controller or timer?
Any chance of a drawing? I’m a real novice.
 
Any chance of a drawing? I’m a real novice.

Pool pump is normally an induction motor, draws massive amount of current on startup. Running that PV direct is not practical, would need large inverter and a PV array at least 5x as big as operating power. Battery inverter and car batteries to give surge could work, but still needs big inverter.

You could find variable speed pumps for a PV direct system, probably at great expense.

Grid tie net metering PV is the best way to go from a technical and cost point of view, except for permitting cost and hassles.

If you installed a right-sized grid tie PV inverter behind the pump switch, that could avoid the issues or at least go unnoticed (except for that big array visible to anyone looking.) Benefit of this is you can use any old grid-tie PV inverter found used or old-stock on eBay (only get one with UL-1741 certification.)

Grid tie system with zero-export is another way to go. It could be sized bigger than pump or other household loads, but has current transformers near your meter to measure current flow and reduces its output when necessary so no power goes back to the grid.
 
I just did my well and pool pump with the used Santan panels and a Growatt all in one via a sub-panel off-grid. Cheap easy, very straightforward. Set the pool, which runs at 500w, to run 8 hours a day when solar is available. Made a 24v50ah bat from some used Lifepo4. A fun project that all-in costs around 2k.
I set up a 4kW all in one (AIO) inverter with a 48V 190Ah SLA battery bank as a grid outage backup system. I'm now installing some solar PV (6x370W panels) to keep it topped up and with all that energy available I figure I may as well supply power for the pool pump.

My pump draws ~900-1000W on its start up cycle and ~320W on its all day pump cycle which is about 2-2.5kWh/day. Duty cycle varies with season.

I've tested it starting and running just using the batteries via the AIO and it handles it all very comfortably, as it should. I'd imagine if all I wanted to do was run a pool pump I could use a smaller spec AIO inverter, e.g. 12 or 24V and a bit less solar PV. Just need to make sure you spec sufficient battery capacity.
 
It's all in the pump you choose.
Powering an existing 1 HP or 2 HP induction motor will take quite a bit.
If your existing systems has a different kind of motor, or you change yours, the PV will be much cheaper.
Ideally you would have a brush-type or brushless DC motor that varies in speed with voltage. Then just hook up some panels.
 
10 used(cracked backing) panels from Santan(35 each+delivery), 24v Growat LVM eBay(689), LifePo4 came from the company with the ape logo? can't think of the name. Subpanel with breakers Amazon(35). Panel brackets Aliexpress (5 a set). For large wire, I chopped up an old set of jumper cables and was able to snag some leftover pv wire from a neighbor. Pic below shows some normal usage, the spikes are the well filling the pressure tank and the 500w in the middle is the pool pump.
Hi! It seems to me you know what you are talking about. Perhaps you can help me with a question? I have a dc solar pool pump 3hp I need to run at night. What do I need to do in order to connect a battery backup of some sort to make this happen? Approximately how much would something like this cost?
 
Hi! It seems to me you know what you are talking about. Perhaps you can help me with a question? I have a dc solar pool pump 3hp I need to run at night. What do I need to do in order to connect a battery backup of some sort to make this happen? Approximately how much would something like this cost?
Thank you! Will this run a 3hp pump? Approximately how long will it run?
 
Hi! It seems to me you know what you are talking about. Perhaps you can help me with a question? I have a dc solar pool pump 3hp I need to run at night. What do I need to do in order to connect a battery backup of some sort to make this happen? Approximately how much would something like this cost?

Unless you build a DIY lithium battery pack, expect commercially made batteries (lead-acid or lithium) to cost $0.25 to $0.50/kWh of power drawn from them, by the time they are worn out. For lithium, that can be a decade of cycling once per day. Lead-acid can't do as many deep cycles, so you can size it to last a decade, or you can size it smaller to last a couple years.

PV panels, charge controllers, and electrical + mounting stuff will cost about $0.05/kWh amortized over a decade, based on about $1/watt purchase price (assuming DIY labor.)

If the pump is in the range of 12V, 24V, 36V, or 48V, charge controllers are readily available.
You should set up a control which turns off the pump in case of low battery.

You need to determine operating current for your pump - label should give an idea. A DC clamp meter would read it. Then you can determine how many kWh the battery needs to hold, and how much PV.
Is it OK that after cloudy day, you don't have enough charge to run through the night?
 
Unless you build a DIY lithium battery pack, expect commercially made batteries (lead-acid or lithium) to cost $0.25 to $0.50/kWh of power drawn from them, by the time they are worn out. For lithium, that can be a decade of cycling once per day. Lead-acid can't do as many deep cycles, so you can size it to last a decade, or you can size it smaller to last a couple years.

PV panels, charge controllers, and electrical + mounting stuff will cost about $0.05/kWh amortized over a decade, based on about $1/watt purchase price (assuming DIY labor.)

If the pump is in the range of 12V, 24V, 36V, or 48V, charge controllers are readily available.
You should set up a control which turns off the pump in case of low battery.

You need to determine operating current for your pump - label should give an idea. A DC clamp meter would read it. Then you can determine how many kWh the battery needs to hold, and how much PV.
Is it OK that after cloudy day, you don't have enough charge to run through the night?
Wow, this is extremely helpful, thank you. So if I am reading this correctly, because I have a dc pump, I do not need a converter correct? I'll only nerd batteries, a charge controller and mounting stuff? I already have the panels. I only need the pumpt to run approximately 3 hours after the sun goes down. Thanks again
 
Yes, if the pump is good over the battery voltage range.
Some SCC have control signals which can activate based on voltage or maybe SoC. That plus a timer could activate a power relay.

Why only after the sun goes down? Ideally would be run while there is sunlight, so minimal battery needed.
Pools need more filtering during times of more sunlight.
 
Yes, if the pump is good over the battery voltage range.
Some SCC have control signals which can activate based on voltage or maybe SoC. That plus a timer could activate a power relay.

Why only after the sun goes down? Ideally would be run while there is sunlight, so minimal battery needed.
Pools need more filtering during times of more sunlight.
The pump would operate off the panels directly during prime sunlight hours which in my case is about 8am to 1pm. After that, it would need to switch over to the battery for 3 hours so I can get a full 8hrs of pump run time total. If I get a controller that activates based on voltage plus a timer like you suggested, that should suffice correct?
 
Midnight Classic, for instance, has an "AUX" relay that can switch according to voltage, and "AUX1" switching according to SoC (or so it says).
I'm not clear how SoC is determined without measurement of current in/out of battery. Counting coulombs would help, and voltage also varies with current draw.


Your PV array, instead of being a single optimum orientation (facing South with some tilt) can have a portion aimed at AM sun and a portion aimed at PM, so it's power output is more flat with time and battery doesn't need to level power as much.
 
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