Why hotel pools should take the plunge into solar thermal heating

Solar power is attractive for hotels trying to cut chunks out of their energy tab, but not too many of them are connecting solar and thermal heating solutions to the hotel pool. Here are three things operators need to know about thermal solar power before they can swim in savings.

1. Pools are Designed for Solar Thermal Heating

Freeman Ford, CEO of solar heating company FAFCO, said hotels are looking at pools all wrong. "Resort operators view pools as an essential ingredient to the guest experience, and they're not wrong," he said. "But solar people view pools as a storage tank."

What he means is that while pools can be difficult to heat, they retain heat easily. Ford recommends pumping solar thermal energy into pools early in the morning when the sun is out, making it hard for the surface to cool during cloudy periods. Additionally, pools already require circulation systems, which allow them to retain energy.

On top of this, pools require more energy to heat than any other part of a hotel. Resort properties in particular know their guests want warm water. 78 degrees may be a temperate climate outdoors, but if a pool thermometer comes up with that number nobody is going in. Many operators aim to hit a sweet spot between 82-85 degrees Fahrenheit, which is warm enough to satisfy guests without expending too much energy. Heating a pool is expensive though, and increasing a pool's temperature by even a single degree can be costly. For this reason, hotels that can are turning to solar energy.

2. It's All in the Physics

According to Ford, solar thermal heating is not a big secret, with the ancient Greeks supposedly trying their hands at it. Solar electric technology relies on redirecting electrons to create heat, and while that makes it easy to collect energy, it can be difficult to make use of all of it. The primary difference between the two technologies is that solar electric power is converted directly into electricity, while solar thermal power is used directly to heat water or air. Ford said solar thermal power can retain up to 20 percent more energy over its electric counterpart because of how the mechanics of the operation work at the atomic level.

“Solar electric power relies on making electrons go where they don’t want to. Electrons are very difficult to control, so it’s just simply not possible to retain all of the energy you gather,” he said. “Solar thermal, on the other hand, speeds up photons, which is much more manageable.”

In addition, some climates are actually too hot for solar panels to be completely effective when converting energy directly into electricity. Solar panels can get extremely hot, and those temperatures can be difficult to handle when it comes to energy collection.

“Meanwhile, those hot environments are the ones where thermal heating really comes into play, because the warmer it is outside the higher the starting temperature is to begin heating a pool,” Ford said. “The closer you get to the equator, thermal energy becomes easier to collect and solar electric works less and less well.”

3. You Need Space

The ideal place for solar panel placements is on building rooftops, but the kind of large resort hotels that would benefit from a solar thermal installation often utilize their roofs for other purposes. Ford recommends installing panels atop covered garages or other buildings not utilizing roof space, and says hotels need to install anywhere from one-third to three-quarters of a pool’s total area in panels in order to heat the water meaningfully.

“Solar electric installations are commonly going after hotels, but many have limited roof space,” Ford said. “Most operators are interested in doing both if they can, and in a perfect situation they probably should, but operators also tend to be concerned about one bill over another when it come to solar power.”

The good news is that, for interested properties, numerous tax incentives are available should they undertake a solar panel installation. While this can help seal the deal in some cases, Ford said he only needs to ask a hotel three questions to know if they can benefit from solar power.

“What is your electric and thermal load? What does your thermal and electric energy cost you each month? Do you have a reasonable place to install solar collectors? Those are important,” he said. “If they have no roof space then it’s a five-minute discussion. But if they do, they can save.”