A Real World Comparison of Solar Pool Heating Collectors

Pool Companies

Unfortunately, the group that you might think would be the natural source of this information, swimming pool installation & service companies, know little and have little to no interest in supplying an installed solar system. They will typically point you at a stack of cheap solar collectors in their store and say “help yourself”. Some of them will suggest you check on the internet.

Solar Manufacturers & Dealers

However, there is a great deal of garbage and misinformation about solar pool heating on-line. It is being supplied by "less than completely honest" manufacturers, dealers and installers. We pride ourselves on supplying accurate & honest information on all of the solar products we carry and compete with.

Solar Ontario does not accept any of the manufacturer’s comparative performance information, and instead evaluates independent 3rd party testing information. Even this can be difficult to interpret if you don’t have knowledge about solar product testing, for example: Recently, one company selling a product called echo-sun, began promoting their product as being the most efficient ever tested by an independent solar lab. They even published information stating that these results were from a new updated testing procedure - as if this was a good thing. That test indicated their product was at least 10% better than every other solar pool heater. However the other solar pool heaters they subsequently compared themselves to were tested using the old procedure – so the tests results aren’t comparable! This is a deliberate & dishonest attempt to misinform.

Another game played by this same company is to compare outdated product certification data from other solar products to up-to-date data from their own. This practice is also intentional & deliberately misleading.

Third-Party Solar Collector Performance Testing

Below is a table of results from tests performed by National Resources Canada. These tests were done by the government because, at the time, they had a subsidy program (only for commercial & municipal pools) that paid-out according to the energy expected to be delivered by the solar pool heating collector system.

These results are really how the products compare – not what a private lab was paid to measure or computer-simulate in a 2 - 4 hour test.

Solar Pool Heating Collector Comparison Table

Manufacturer

Material of

Construction

FSEC Energy Performance

Heat Collected Per sq. ft. **

April 2011

NRCan Performance Ranking Factor

Feb. 2009 ***

SOLAR ONTARIO How we ranked them in 2002*

(Before NRCan did)

Techno-Solis

Poly Plastic

1006 Btu

.97

2

Fafco Sunsaver

Poly Plastic

1014 Btu

1.00

1

Aquatherm

Poly Plastic

1010 Btu

.92

3

Enersol

Rubber

814 Btu

.69

4

Helicol

Poly Plastic

850 Btu

.58

5

 

* allowing for the effects of average wind speeds.

** Wind speed during test – less than 3 miles per hour.

(FSEC = The Florida Solar Energy Center) 

** https://tcp.fsec.ucf.edu/Certification/Ratings/RatingssummaryPage.aspx?type=1

*** http://www.ecoaction.gc.ca/ecoenergy-ecoenergie/heat-chauffage/v2008/collectors-capteurs-eng.cfm

 

Vacuum Tube Solar Collectors

Manufacturers and distributors of vacuum tube collectors (also known as: evacuated tube or tubular collectors), will quote European test results of their products because the performance can be reported three different ways. They choose the way that favours their collector over all others. This is where the ridiculous collector efficiency numbers between 92% and 97% come from. Most vacuum tube collector’s peak performance efficiencies are somewhere between 40% and 50% if their test results are based upon North American tests.

Manufacturers of vacuum tube collectors also usually claim that because they are more efficient when the weather is cold – you need less collector area than standard solar pool collectors. This is untrue. Because - when the weather outside is so cold that the vacuum tube collectors are more efficient (around 50 degrees F / 10  degrees C), the swimming pool is losing heat so quickly that only a gas heater running at full blast is going to keep the pool warm. No solar system of a reasonable size is going to be able to heat it – and neither are you likely to be interested in swimming, unless you are a polar bear.

We recommend you read our detailed review of Vacuum Tube Solar Pool Heating Systems

Mini Solar Pool Heating Collectors

In the past few years there has been an explosion of small, rigid plastic “solar pool heaters” with clear plastic covers. These are sold almost exclusively at pool stores. These “solar pool heaters” are usually less than 3`x 3` square (1 metre x 1 metre), are made of rigid black plastic and covered by a clear plastic sheet or dome. The performance claims typically say they will heat a pool in a week to 10 days. These “solar pool heaters” are so small that they will have NO measurable effect on heating the pool. If the pool does warm up in the 7 – 10 days claimed, the only reason the pool has done so is because the sun has been shining on it and warmed it up (and the weather has been very warm as well). The manufacturers are preying on pool owners who don’t know the science behind how much energy it takes to heat water. Pools require an enormous amount of heat to get and stay warm. This is why gas pool heaters have three to five times heating capacity of a typical home-heating gas furnace – and they run for hours at a time! There is no way around the fact that solar pool heating systems have to be large to work well!

How do you recognize a good solar pool heating collector?

 

  1. It’s not made of hard (brittle) plastic,
  2. It’s not covered with glass, plastic or made of vacuum tubes,
  3. You can't see through it,
  4. There are no gaps or spaces between the tubes that run up and down the collector,
  5. It’s at least 4’ x 8’ (1.2 m x 2.4 m) in size,
  6. The small tubes in the collector do not run horizontally across the roof,
  7. It has no metal in it other than for clamps or screws – and that metal is stainless steel,
  8. Its warranty is at least 10 years long.

 A bit off topic, but even the best solar pool heating collector will fail if not well installed, so:

 How do you recognize a good solar pool heating collector installer?

 

  1. They install a good - unglazed - solar collector (see above),
  2. They insist that you install an automatic controller for the solar system,
  3. They don’t tell you “all you ever need is 50% of your pool’s surface area”,
  4. They will tell you – “sorry, solar just can’t do the job – you need a gas heater” if a properly sized solar system can't be installed,
  5. They don't have "Spring sales" or automatically discount their quote by $500 for some arbitrary reason. Spring sales & discounting are just a con-game to sucker buyers in with a  fake price reduction. Fall sales may be legitimate for clearing inventory before Winter.
  6. They have installed hundreds of solar pool heating systems and have the photos & written references to prove it,
  7. They don’t post glowing Home Star reviews that they “bought” from the pool-owners by heavily discounting the cost of the solar installation that uses a new solar collector they had only just started selling,
  8. They don’t offer an unusually long installation warranty (more than two years) that is full of exceptions and default clauses,
  9. They don't require that you get on the roof every Fall and Spring to prepare your solar  collectors for the season ahead - or call them to go on the roof for you,
  10. They have experience installing and maintaining a  variety of solar pool heating products on  large variety of roofs & structures,
  11. Their website isn’t full of stock photography or solar systems they haven’t installed,
  12. Ideally they will have had a fair amount of experience installing solar pool heating systems for commercial or municipal clients. These clients are much more critical of the quality & durability of the solar collector and the installation work done.

Next: A Detailed Review of Vacuum-tube Solar Pool Heating Systems