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Hi all, another noob.


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Hello everyone.

My knowledge of solar is limited to 12v DC applications to run a fridge when we go camping off grid.

I would like to know if it is possible and/or viable to run the pool pump off solar. No batteries.

My garden would suit a ground level installation for the panels and very close to the pool pump itself. 1.1 kw pump that circulates the pool and 10 solar roof mounted panels. To get the best out of the heating panels requires more pump time than is needed to just keep the pool clean and sends my Eskom bill up.

What do you think, viable project or not ?

 

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Pumps are some of the higher usage items in a house. You can add the pump to solar, but it has to be big enough to handle the pump's load (naturally) and then you need to handle the pump's start current. Start current of pumps can be as high as 7x the normal rating. You can handle this from Eskom power which will be the cheapest option, or you need to cater for the start in your panels and inverter. 

You also get solar specific pumps, but these are more to still move water when not full sun at a reduced rate. For a pool you need to circulate at a specific rate to make your kreepy work, so they will not be the best option.

 

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Thanks, looking at those pumps now, and reading lots of threads here too.

I think that if this could be made to work efficiently and reasonably priced it would be beneficial. My thoughts are to get the best heating benefit from the pool panels I need to run the system say 9 AM to 4 PM. Assuming 1 kw per hour, that is 7kw per day x 30 = 210 kw per month

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1 hour ago, Louisvdw said:

Pumps are some of the higher usage items in a house. You can add the pump to solar, but it has to be big enough to handle the pump's load (naturally) and then you need to handle the pump's start current. Start current of pumps can be as high as 7x the normal rating. You can handle this from Eskom power which will be the cheapest option, or you need to cater for the start in your panels and inverter. 

You also get solar specific pumps, but these are more to still move water when not full sun at a reduced rate. For a pool you need to circulate at a specific rate to make your kreepy work, so they will not be the best option.

 

I run my pool all day, using just the solar panels on a 5kw inverter. The pump is a 750w pump and the spike is just under 1kw. 

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Thanks, so would I be far off in looking for a 2KW inverter and panels to produce 1.5 or so ?

I am not worried about the rest of the house at this stage as the geyser is taken care of with a solar geyser and geyser wise system. So my thoughts run to dedicated system for this pump.

 

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22 hours ago, Stranger said:

To get the best out of the heating panels requires more pump time than is needed to just keep the pool clean and sends my Eskom bill up.

I have a 45 000 liter pool. On roughly 80% of the surface my double garage roof I have (now bypassed) some of these solar "mats" (multiple rows of little black pipes) that are warmed by the sun before the water returns to the pool. I have found a bubble pool cover way more effective at raising the pool temperature. Another major benefit is that I have not used tap water in over three years to top up my pool (do at times add a bit from rain water harvested from the roof) - the cover also helps a bit to keep leaves and crap out of the pool. Just get a cover with a roll up station other wise opening the pool feels too much like a chore. One way to reduce your particular pool pump running time...

If looking at other ways to reduce electrcity costs I found the following when looking at the various options:

1) Variable flow pumps (pump runs slower depending on settings - drawback is that these are quite expensive and you pool cleaner may not work on the lower settings).

2) Purpose made solar (PV) pool pumps (normally a DC motor that will start running slowly when solar output is low and then pick up speed as solar output increases then slow down again as solar output decreases - you basically leave the pump to run the whole day. Again also not cheap. Think the bundupower ones are PV DC).

3) PV add-on options for exisitng AC pumps. (normally some variant of a solar controller and Variable Speed Drive - the Speck systems as mentioned by @Richard Mackay should be a variant of this. Again not cheap). I suspect the specks are actually made by Microcare and sustainable still lists the actual microcare options. I normally try to support local but at the time could not get any response from Microcare unfortunately

In the end when I looked at these options the intial cost just did not make it worthwhile in terms of return on investment for me . 

If I was going to look at this now again, purely with an eye on keeping electricity costs down I would look at my options for a grid-tied inverter as mentioned by @Plaashaas.

I would consider splitting my DB and maybe have my pool and kitchen on a "savings circuit" which is fed by a grid-tied inverter which can blend incoming AC (the idea is NOT to export anything to the grid). Having the grid-tied inverter allows Eskom to help start the motor without needing a 5000W+ inverter (which after startup will be running at ~1300W). Having the kitchen on this same "savings circuit" means that at times when the pool is maybe not runnning that my fridges get the benefit of reduced eskom power consumption from the Rxxxx-xx system I installed. I also do not have to worry will my pool motor even work with a VSD, if it does having another component that can fail etc. If some clouds drift past the sun the pool pump does not sound like a learner driver trying to still master clutch control.

 

Part 2 of my blog:

21 hours ago, Stranger said:

so would I be far off in looking for a 2KW inverter and panels to produce 1.5 or so ?

The major issue is the startup. My 1.1kW pool pump (actual brand name "Quality".....) with a 7A run rating draws at least 30A in the first 100ms (i.e. 30A*230V=6900W). Even though i.i.r.c.  @plonkster started a 1kW pump with a 3kW victron you will likely want to go a bit bigger on the inverter.

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3 hours ago, introverter said:

I have found a bubble pool cover way more effective at raising the pool temperature.

I once looked at pool heating and I was surprised how effective this was, from memory it was something like the heating capacity could be down-scaled 25-30% with one of these.

Definitely, first stop when considering pool heating or just keeping it warmer longer.

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13 hours ago, phil.g00 said:

I once looked at pool heating and I was surprised how effective this was, from memory it was something like the heating capacity could be down-scaled 25-30% with one of these.

Suspect lowering convective heat loss is a big contributor of the blankets (blowing on your tea to cool it down vs covering the cup with the saucer and then blowing). In summer it is almost too effective - pool water at > 30 degree C not much of a way to cool down 

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