The Sun Can Heat Your Pool Even When the Weather Is Cool

Changing economics are making solar energy viable for a growing number of New York City co-ops and condos and other multi-family dwellings. Under one unique financing arrangement, smaller co-ops are installing rooftop solar panels with no out-of-pocket expenses, then repaying the loan through tax incentives and savings on their electric bills. A group called Brooklyn Microgrid has installed solar panels on 11 neighboring rooftops near Prospect Park, passing along the surplus electricity to neighbors who can’t yet afford their own solar panels. And now, along comes another use for solar energy: the cost-free heating of swimming pools.

“When you have an outdoor pool without a heating system you’ll have to wait until mid-July or August for the pool to get warm,” says Mike Mazzeo, partner at New Jersey-based Solar Living, which provides design, installation and service of solar pool-heating systems. “We can get that same temperature all through the season from Memorial Day through Labor Day, and the best thing about it is, there is no fuel bill.”

The 293-unit Changebridge Condominium Association in Montville, New Jersey has a 20-by-40-foot pool. Nine years ago, at a cost of about $7,000, the condo board installed a solar heating system on the pool, which had previously been unheated. “The pool does get warmer sooner,” says property manager Marilyn McClure. “Residents do appreciate that very much.”

Typically the area needed to install solar heating is equal to about half the size of the pool. Unlike rooftop solar panels that generate electricity for lights and appliances, these pool-heating solar collectors transfer the heat directly to the water. “The solar collectors capture the heat,” says Mazzeo. “The water is then transferred through the piping of the collectors back into the pool. Typically the solar collectors are on the roof” – the preferred setup in space-starved New York City – “but in one case at a condominium in Clifton, New Jersey, we were able to use an area on the property that was basically a drainage ditch, an unused grassy hill. They were previously spending about $5,000 per season to heat the pool.”

The cost of installing a solar heating system for a large pool is about $20,000 to $30,000, Mazzeo says, with annual savings of about $7,000 – meaning the system usually pays for itself in five years or less.

While most rooftop solar installations come with tax incentives and tax credits, this is not the case for solar pool heating. “And quite frankly it’s not needed,” says Mazzeo, “since it pays for itself faster than [rooftop] solar with all the incentives combined.”

The solar pool heating system provides temperature control and will deliver heat only when it’s needed. The system shuts down automatically when the pool reaches its target temperature. The maintenance cost is also low. “In the past nine years we only had to call Solar Living once for a very minor problem,” says McClure. “Solar pool heating is not cost-prohibitive.”

Yet, as with any sun-powered system, those that heat swimming pools rely on an abundance of sunshine. “The sun has to be out steadily for three to five days in order to warm up the pool and make the solar panels work,” says McClure. “We’ve had unusually cloudy weather, and you need at least three days of continued sunshine to warm up the pool.”

The systems have an advantage beyond saving money on energy bills. “It’s also safer than other systems,” says Mazzeo. “There have been incidents of gas lines catching fire and explosions of propane gas. Also, when the roof is paneled with solar panels, that will lower the cost of air conditioning. The roof is not getting hot because the heat is being directed to the pool.”

Warm swimming pool, cool apartments, lower energy bills: for cost-conscious co-op and condo boards, it’s a win-win-win.