A recent article in the March 2012 digital issue of AQUA Magazine highlights solar pool heating with heavy input from our industry-wise Heliocol solar pool heating staff. Kudos to Director of Marketing Tod Ellington, Vice President Bob Zrallack, National Sales Manager Loren Zucconi and Senior Professional Engineer Michael Studney for sharing their considerable solar industry knowledge with AQUA Magazine readers.
Solar Points, AQUA Magazine, March 2012
by Eric Herman
Experienced pool and spa owners will often complain that it simply costs too much to heat their water. Rising energy prices result not only lighter billfolds but also shorter swimming seasons and ultimately diminished use and enjoyment of their vessels. For those reasons and more, solar water heating systems have remained a popular heating option, which when installed properly can transform the frustration of obtaining warm water into the joy of affordable luxury.
|A recent article in AQUA Magazine outlining the benefits of solar pool heating systems.|
The notion of harnessing the sun’s energy to serve our earthly needs in the form of a ready and renewable energy source is hardly anything new. There’s an inescapable logic to utilizing the inexhaustible source of energy that is our sun in favor of burning fossil fuel.
And as energy prices continue to rise, the appeal of heating water for pools and spas in particular using the sun becomes more and more enticing for many consumers who want to both save money and extend their swimming season without their lips turning blue. And for those concerned about “going green” it doesn’t hurt that solar heating leaves virtually no carbon footprint.
That’s all been good news for solar manufacturers, who currently report that even through the tough economic conditions of the past four years, the market for solar heating, both on the residential and commercial sides of the market, has remained steady and has even made inroads in places they wouldn’t have expected. Even homeowners in areas such as the upper Midwest and Northeastern U.S., regions considered less likely to turn to solar to due their colder climates, have embraced solar heating.
Despite the ironclad logic behind solar thermal heating systems, successfully applying the technology does require hitting a handful of key technical concepts as well as governing client expectations. Here are a few of the main issues that need to be addressed in order for consumers to enjoy the limitless bounty of the sun’s free energy.
The good news is that all of these points boil down to basic common sense and when presented to clients in the right light, solar heating becomes more appealing and attainable.
Those who install solar heating systems must be part plumber, roofing contractor and electrician. That’s why manufacturers strongly recommend that homeowners turn to qualified dealers to size and install their systems and not take on the challenge themselves.
Hydraulic calculations, although not terribly complex, need to be considered with issues such as pump sizing
relative to the flow requirements of the solar panels, as well as resistance provided by vertical lift to the panel locations. And the plumbing connections need to be properly installed to avoid leaks.
On the electrical side, solar systems require connections to automated valves and heating control systems.
Again, although not complex by any stretch, those connections require an understanding of basic electrical installation techniques and hardware.
And finally, rooftop installations require making small numbers of penetrations to secure panel-mounting hardware. Proper use of sealants and flashing is therefore critical to avoid leaks.
For these basic reasons, solar pool heating should not be viewed as a do-it-yourself proposition.
As is true of most technologies, consumers should be informed in clear and understandable terms what to
expect from their systems in terms of performance.
They need to first understand that solar heating systems operate when the sun is out and therefore it’s necessary to circulate their pool’s filtration systems during the day, as in the vast majority of cases, the solar system will run off the primary circulation pump.
Consumers should be aware the solar heating is most effective when viewed as a daily heat maintenance source. How fast a system will raise water temperatures depends on the exposure to the sun and the desired
temperature rise — which in pools will typically top out at about 90 degrees. Depending on ambient temps and other variables, solar heating systems may take two to three days or longer to generate desired water temperatures.
A client who swims for exercise may only want temperatures in the mid-70s and in a mild climate, a properly
sized solar heating system will bring the water to the temperature in relatively short order, and evenly maintain
it over time. By contrast, a client who wants temps in the high-80s and lives in a cooler climate can also achieve that, but it will take longer to raise the temperature to the desired level.
Because solar heating systems are subject to the weather, clients should be reminded of basic pool facts such
as the cooling effect of rainfall and the required time needed to reheat the water. In most cases, clients are surprised by what they can achieve in terms of heat rise and maintenance, so long as they’ve been properly informed about the realistic limitations of their systems.
Meets The Wallet,Meets The Eye
When it comes to payback on investment, solar systems consistently outperform expectations. The variables
impacting return on investment include cost of heating in the area, the size of the pool, desired temperature and, of course, prevailing climatic conditions.
Clients who have used fossil fuel to heat their pools can easily calculate the savings — and the numbers are typically impressive enough to motivate serious interest in obtaining a system. As a general rule, manufacturers report that in the vast majority of situations, the systems repay their initial costs within two years.
By contrast, perhaps the most vexing client concern involves the appearance of the panels themselves.
Because they do consume significant surface area and are typically installed on roofs, the panels are quite visible. Some suppliers now offer panels in different colors that help blend with roof material.
Beyond that, the message to consumers is that most people come to see the panels in the way they see a satellite dish, television antenna or even power lines. They simply become part of the accepted scenery. And when the cost savings and increased enjoyment of the water is factored in, the appearance of the panels becomes far more forgivable and even potentially a point of pride.
Size And Exposure
Manufacturers size solar systems based primarily on surface area of the water rather than volume, based largely on the fact that approximately 70 percent of all heat loss in a body of water is due to evaporation. It’s common for suppliers to recommend that the surface area of the panels equate to 80 percent of the surface area of the water.
Again, depending on climate and desired heat rise, the sizing may change, perhaps taking the size of the
panels up to 100 or 120 percent of surface area. By contrast, there are situations, especially in warm climates, where systems can be sized as low as 50 percent of water’s surface area.
Because evaporation plays such a huge role in heat loss, all solar heating professionals recommend the use
of some type of solid cover, whether a floating solar cover or a solid safety cover. Simply preventing evaporative losses using a cover will typically more than double overall system efficiency.
As a side note, when systems include fountain elements or waterfalls, which can dramatically add to evaporative losses, many installers and manufacturers will recommend upsizing the panels to compensate.
Exposure to the sun is essential, of course, and in situations where adequate exposure is not possible, the
most staunch solar heating advocates will admit that the systems may not be worth the cost and will most likely only lead to unsatisfied customers.
The rule of thumb here is simple. In the Northern Hemisphere, solar heating panels should optimally be
mounted when facing within 45 degrees of southern exposure. Otherwise they will only be in direct sunlight during the summer months, when heating is less of a concern. East and west facing exposures can still be effective, although they could require upsizing or moderated client expectations for performance. Systems installed on flat roofs are perfectly acceptable.