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Cool PV - combined solar panels and pool heating


#1

I’m in the midst of costing a solar passive designed house and was looking for information about solar panels when I came across Cool PV. It’s a combined solar panel and pool heating system. From the little bit of online research I did I found that the efficiency of the panels is definitely increased by keeping them cooler.

Is there anyone with experience in these type of systems? Are they better than separate standard solar and pool heating? On paper it looks like a great way to combine my want for solar panels and to heat our pool.


#2

Hi Erin

Welcome to the forum. I hadn’t heard about these panels so it was interesting to do a bit of research to find out about them as we have both solar and solar matting. So it may have been of use to us.

What I found doesn’t look good to me.

Firstly, the developers of CoolPV, Fafco Solar Energy don’t seem to be a very reputable and quality oriented solar business: Fafco reviews.

Then, I went searching for reviews of the CoolPV. What I found, was very mixed, and none of it very good.

So while in principle you are right, that keeping the panel cooler helps with efficiency, in this case I couldn’t find any evidence that the CoolPV improved the efficiency (aside from generalised sales claims).

Any potential efficiency gain from cooling would depend on how warm your pool was, because you might be pumping up warm water not cool. On the other hand, how well it heats your pool is questionable, and depends on the size of the proposed CoolPV array, the size of your pool, the weather, and your location. The comments I read were that it doesn’t seem efficient at heating the pool compared to rooftop solar matting.

There were also cautions that combined water/PV panels had more points of failure, and potential degraded performance due to the need to have separation between the two systems in the one panel.
(See https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panels-for-your-home/364453-solar-electric-solar-water-opportunity-coolpv &
https://www.troublefreepool.com/threads/cool-pv-vs-thermal-solar.159953/)

I will be interested to hear what others have to say.


#3

Indeed it does.

Assume this is the product?

Is it worth considering?

The sales pitch for the CoolPV suggests it is a niche product. It targets pool owners who need pool heating and want the benefits of solar PV. One that also solves the problem of limited roof space facing the sun.

If it is such a great solution, how many or how few competitors are there with a similar product?
It could be an emerging market. Hence very few. Or a very limited market and only customers who will pay a premium/compromise to use limited roof space?

However if the product is cheaper than two separate systems the market might be very large? Pools are very common and one of the bigger expenses of pool ownership is the cost of running the pump. Something you can run in the day time for free off solar PV. Some are always looking to get more use out of the pool for longer in the year so the heating would appeal.

Is it cost effective?
Does it perform as promised?
Is it reliable?

For heating a pool which can utilise low grade heat it may be cost effective?

Is the “Cool PV” solution as cheap as buying a separate PV and Pool Water solar heating system? This assumes there is enough suitable roof space for both.

It may help others in the community in the future if you decide to get comparative quotes the overall results might be shared. :smiley:

It would seem reasonable to expect any quote for a “Cool PV” system worth considering would come with written performance guarantees. Annual energy production from the PV and also for the thermal performance of the pool heating system.

@meltam has offered some useful feedback on other considerations including reliability, reputation and reviews. Given typical solar PV panels are offered with very long warranties 10 years plus for the panels and 25 years for performance, you expect them to last a very long time. Is the wet system design in the “CoolPV” product going to last as long with minimal performance loss or failure?

A bit of cynicism:
The marketing material talks about “UP TO” often. That has no real value except as virtual loo paper. To counter this the panels have both electrical and thermal performance data appended to the marketing material. So the CoolPV system designer should be able to provide complete performance outcomes for each specific location.

Yes! it still looks good on paper! :upside_down_face:

p.s.
Some points to ponder.

We’ve had pools in three houses and appreciate that they can be too cold for comfort. The further south you live the greater the need for heating. In the north of Queensland we found that we needed the opposite (pools can get too hot) for half of the year.

A contradiction might be that in mid summer when the solar PV panels get hottest the last thing needed is a hotter pool, and turn the panel cooling off! But in mid winter or if the pool is way down south the air temperatures are cooler and strength of the sun weaker. Under those conditions the total panel output and hence efficiency benefits of cooler PV panels will be much reduced (halved?).

How effective the “CoolPV” panels are at transferring thermal (heat) energy to the pool water will also vary. The panel data sheets provide results for a nominal scientific standard set of conditions. A guide only. They are not representative of the real world. The energy transfers/benefits will depend on your latitude (North/South) roof orientation, day of the year, weather/clouding, pool water temperature, etc.

As an aside.
The following paper illustrates the potential for efficiency gains through cooling on yesterdays technology PV panels. And just how nerdy this topic could become.


#4

That is indeed the product. Thanks for the info. There are so many considerations to make albeit I don’t have the IQ to assess the data and figure out the best course of action. Is there anyone I can contact who can take the data from our house plans, climate and energy needs and figure it out for me?


#5

I’ve noted your other topic and enquiry re choosing appliances for Solar passive houses is related.


It would seem likely that your solar passive house designer might have the skills required, or have a positive relationship with another consultant who can?

Our Qld building certifier had to provide an energy efficiency audit for a recent planning application. That may also be an avenue of enquiry in your state, based on who is available locally, and their business expertise?

If you wish to tackle this yourself, it might be useful to begin with a list of your goals or expected outcomes.

It may also be useful to list your major energy consumption items and consider these first. For inside your solar passive house @TheBBG and @gordon have already provided some great feedback at the other topic.

For a typical home the biggest daily energy users are likely:

  • Heating and cooling, (possibly not a need for your house)
  • Hot water,
  • Pool,
  • Cooking (cook top, oven),
  • Fridge/s

The balance of the loads that are less significant in total consumption include dishwashers, washing machines and driers, TV - entertainment systems, lighting and misc electrical. Choice has lots of great information and advice on all these and also cooking and fridges.

And optionally you might need to also provide for:

  • The backyard shed,
  • House hold water pump and treatment if on tank water,
  • Sewage Treatment Plant if not on services,
  • Bore pump if rural.

There are lots of choices to make. And often more than one energy option.

Eg
If you go all electric per @gordon other post, are you also going off grid? If you go off grid and all electric you might choose a heat pump style hotwater system. Alternately you could choose an evacuated tube solar HW system with 200l storage tank with gas backup for low solar days?

Even the pool has choices that impact energy use and cost. A quality retractable thermal pool blanket may be a good call. Reduced cleaning, less water loss, less chemical dosing, less heat loss?

It might be beneficial to your planning to gain some insight and knowledge by talking with reputable local pool suppliers about your goals. They will suggest products and options. They should be able to provide budget costs and enough information to help with the decision making process. If you have concerns about a particular product or supplier, there is always Choice and the Community.

The same approach might be useful for the other key decisions with the final design of the property?