Electric solar pool heating question

[sir sanders zingmore]

Quick question for the SNA brains trust. 

 

Is there a way to use the electricity generated by solar panels to heat my pool?

I’m not talking about solar heating where you have the black pipes running on the roof. What I mean is some sort of electric hot water heater than runs off solar.

 

Ideally it would only use excess power from the panels. So it would be “smart” enough that if we are using power in the house then only the excess could be used for heating (so it has a lower priority to the rest of the electricity being used in the house)

 

does such a thing exist ?

[Addicted to music]

 Normal solar hot water panels are not ideal for swimming pool water as this is chlorinated or salted and has the potential to degrade the fine heating elements that's used.  Most are design for a certain PH level.   

The panel that are sold in the last decade are all cheaply made with the cheapest material.  I should know, I have had all 3 panels replaced.

[sir sanders zingmore]

Why would the water need to go anywhere near the solar panels ?

they'd just generate the electricity for the heater

Edited December 11, 2016 by Sir Sanders Zingmore

[lusk]

Can use a heat pump which is basically an AC in reverse where you reclaim heat off the condenser for heating the water. It will be more efficient than using something with electric heaters.

 

https://www.zodiac.com.au/heat-pumps

 

Not sure how you would do the power side, but you could put your heat pump on a timer, adjust the on time (while considering pool water temperature) until the amount of power you put back into the grid goes to zero. Thats if you put any power back into the grid at all.

 

Edited December 12, 2016 by lusk

[sir sanders zingmore]

28 minutes ago, lusk said:

Can use a heat pump which is basically an AC in reverse where you reclaim heat off the condenser for heating the water. It will be more efficient than using something with electric heaters.

 

https://www.zodiac.com.au/heat-pumps

 

Not sure how you would do the power side, but you could put your heat pump on a timer, adjust the on time (while considering pool water temperature) until the amount of power you put back into the grid goes to zero. Thats if you put any power back into the grid at all.

 

I think that's what I meant, thanks. 

Not cheap though

[t_mike]

Use an insulated pool cover. That makes a massive difference.

[Benje]

Sir Sanders

 

the use of a heat-pump to heat your water sounds good - cool your house and heat your pool at the same time.  Do it during the day with your PV.

Problem is that the time of year when you need to heat your pool (spring and autumn) is not the time when you need to cool your house.

 

The insulated pool cover's are a good idea.

 

If you want something else (to extend the swimming period at start/end of season) then you probably need to select a dedicated pool heater.  I have no idea/experience here.

Note that PV system output is normally high for roughly the 6 months of daylight saving (more accurately, between equinox dates for spring and autumn).

You could be reasonably confident of high solar PV output 2 to 3 hours hours either side of solar noon for that 6 month period unless heavy cloud occurs.

Edited December 12, 2016 by Benje

[Guest jakeyb77]

3 hours ago, Sir Sanders Zingmore said:

Quick question for the SNA brains trust. 

 

Is there a way to use the electricity generated by solar panels to heat my pool?

 

I’m not talking about solar heating where you have the black pipes running on the roof. What I mean is some sort of electric hot water heater than runs off solar.

 

 

 

Ideally it would only use excess power from the panels. So it would be “smart” enough that if we are using power in the house then only the excess could be used for heating (so it has a lower priority to the rest of the electricity being used in the house)

 

does such a thing exist ?

 

move to QLD!

[sir sanders zingmore]

7 minutes ago, Benje said:

Sir Sanders

 

the use of a heat-pump to heat your water sounds good - cool your house and heat your pool at the same time.  Do it during the day with your PV.

Problem is that the time of year when you need to heat your pool (spring and autumn) is not the time when you need to cool your house.

 

The insulated pool cover's are a good idea.

 

If you want something else (to extend the swimming period at start/end of season) then you probably need to select a dedicated pool heater.  I have no idea/experience here.

Note that PV system output is normally high for roughly the 6 months of daylight saving (more accurately, between equinox dates for spring and autumn).

You could be reasonably confident of high solar PV output 2 to 3 hours hours either side of solar noon for that 6 month period unless heavy cloud occurs.

 

 

Ummmm, what's "PV"

[mrbuzzardstubble]

29 minutes ago, Jakeyb77 said:

 

move to QLD!

He can't. They won't let him in. His IQ's too high.

[Guest rmpfyf]

@Sir Sanders Zingmore

 

Possibly but heat pump electrical loads are high relative to what most PV will actually export, they're not as variable as you'd like and you'll be running it not intermittently (e.g. offpeak too) to noticeably heat your pool. And you'll best need to insulate, as others have mentioned, which you may or may not want to do with kids or pets. 

 

You can feed that excess to drive a pump at 1-2kW (which is more reasonable) to your usual black pipe collectors (cheaper) or evac tubes (hellishly more expensive for something that's ok with chlorinated water) or evac tubes into a liquid-liquid heat exchanger (not uncomplicated and moderately expensive).

 

Pure inline electrical water heaters will need way more power than you export, and are expensive. Can work for a spa. 

 

If you're dumping it into a heat exchanger that you also use for your home domestic hot water - and it has excess thermal capacity that can drive a pool too (via the aforementioned heat exchanger) - that does work, and can be very efficient. But it's not a bolt-on design, you'll be reengineering your home thermal system.

 

Seriously... black tube driving a pump on an export-triggered relay with a lockout timer, and you're done. Very efficient and will work just fine. Dump any excess export into aircon or domestic hot water.

[Benje]

Sir Sanders

 

PV = Photo Voltaic, = solar.

 

Also, what rmpfyf said is very good.

Cheapest heating source is the sun, so 'black tubes' to heat the water, with a pump driven by solar (PV) during the near-solar noon period.

Just cut back on the heating in the middle of summer, as the water will be getting quite hot.

 

The only problem with this solution is finding the best locations on your roof for the solar panels (PV) and for the black tubes.

You may run out of ideal roof space, depending on the orientation.

The PV panels will probably require the best sun orientation away from shadows, with north/north-west orientation preferably.

[lencolad]

Butchertech - do not be tempted to try this at home please kids.

Put one of these Lucky Dragon brand heaters in the pool via a timer.

Almost certain to burn out the timer's contacts (internal switch) very quickly and almost certain to wind up with the plug immersed in the pool causing mayhem.

 

for amusement purposes only

 

you're welcome

Edited December 12, 2016 by lencolad

[Saxon Hall]

Yeah. If you use one of those, you won,t be so lucky


Sent from my F1f using Tapatalk

[mrbuzzardstubble]

2 hours ago, lencolad said:

Butchertech - do not be tempted to try this at home please kids.

Put one of these Lucky Dragon brand heaters in the pool via a timer.

Almost certain to burn out the timer's contacts (internal switch) very quickly and almost certain to wind up with the plug immersed in the pool causing mayhem.

 

for amusement purposes only

 

you're welcome

Or add 12 buckets of silica gel (exothermic reaction) and if the water's too hot, 1 bucket of sodium nitrite (endothermic) should make it comfortable

[comfortablynumb]

3 hours ago, Benje said:

Sir Sanders

 

PV = Photo Voltaic, = solar.

 

Also, what rmpfyf said is very good.

Cheapest heating source is the sun, so 'black tubes' to heat the water, with a pump driven by solar (PV) during the near-solar noon period.

Just cut back on the heating in the middle of summer, as the water will be getting quite hot.

 

The only problem with this solution is finding the best locations on your roof for the solar panels (PV) and for the black tubes.

You may run out of ideal roof space, depending on the orientation.

The PV panels will probably require the best sun orientation away from shadows, with north/north-west orientation preferably.

 

Benjie is on the money. Solar with it's own, stand alone PV powered pump.

While you are at it, get a bigger solar array and run your pool pump from it as well.

Also, if you are concerned with power consumption, consider a two speed or variable speed pump for the filter.

[Benje]

can you use the same pump, with a valve to send water through the heat pipes?

[comfortablynumb]

1 hour ago, Benje said:

can you use the same pump, with a valve to send water through the heat pipes?

 

Yes, it can be set up like that if you want.

Depending on your system, you may need a bigger pump.

You need valves to slow the flow on the solar array. Or the water travels too fast and picks up little heat from the tubes.

Edited December 12, 2016 by comfortablynumb

[sir sanders zingmore]

5 hours ago, Benje said:

Sir Sanders

 

PV = Photo Voltaic, = solar.

 

Also, what rmpfyf said is very good.

Cheapest heating source is the sun, so 'black tubes' to heat the water, with a pump driven by solar (PV) during the near-solar noon period.

Just cut back on the heating in the middle of summer, as the water will be getting quite hot.

 

The only problem with this solution is finding the best locations on your roof for the solar panels (PV) and for the black tubes.

You may run out of ideal roof space, depending on the orientation.

The PV panels will probably require the best sun orientation away from shadows, with north/north-west orientation preferably.

The problem with the black plastic is that the roof space available by the pool is the garage and my pool guy tells me the area is too small. He reckons you need around 1.5 times the pool area and my garage roof is about half the pool area. 

[comfortablynumb]

7 minutes ago, Sir Sanders Zingmore said:

The problem with the black plastic is that the roof space available by the pool is the garage and my pool guy tells me the area is too small. He reckons you need around 1.5 times the pool area and my garage roof is about half the pool area. 

 

He is spot on.

Try a solar blanket first then. A bit of a PITA but it makes a massive difference.

In Qld at least a blanket probably extends the swimming season a month either side. We put it away in summer, water gets too warm to be refreshing. Evaporation isn't an issue. We pump water out of the pool in summer.....

[Luc]

9 hours ago, Sir Sanders Zingmore said:

I think that's what I meant, thanks. 

Not cheap though

Don't be a tight arse. Just buy the pump and forego the next system update ok, think of the boys....they'll love you more as they cavort and splash in sunny Bleak City in the middle of July.

 

Look here  and have a read (if you haven't already)>>>splash&splutter!