We are asked frequently, why can’t one type of solar panel do everything? Specifically, people want to know if you can heat a pool with solar electric (photovoltaic) panels. With the price of solar electricity now much lower than it was just a few years ago, it stands to reason that heating a pool with electricity might now be cost effective. Can you heat your pool with solar electricity? The answer is yes, it can be done; but not directly and it is typically not the best solution.
Solar pool heating panels use solar thermal technology to heat pools. Solar radiation is absorbed and heat is transferred from the panels to the pool water within. This is a very simple and efficient process. Solar pool heating panels can convert as much as 85% of the sun’s energy hitting them into heat energy that is transferred to your pool.
Solar electric panels convert solar radiation into electricity. Using electricity to heat water is very inefficient. In fact, heating or cooling anything (water, air) requires a lot of electricity, and the conversion process is inefficient. Furthermore, solar electric panels commercially available today range in efficiency from 14% – 21% efficiency, far lower than the 80%+ achieved by solar pool heating panels.
If you wanted to heat your pool with solar electricity, you would also need a mechanical means of doing so. That means you also need to buy an electric heat pump. A good heat pump alone costs as much as a solar pool heating system — and you still need the solar electric system, which is very costly relative to solar pool heating systems. In the end, an investment in solar electricity to heat your pool would cost in the range of five times that of a solar pool heater. While solar electric panels are long lasting, heat pumps typically require replacement twice in the lifespan of a solar pool heater, and have moving parts and electronics that are prone to maintenance requirements.
On a good note, if you intend to heat your pool only very occasionally, a solar electric system can take the excess energy produced and reduce your electricity bill. This might fit the needs of people who want to heat a pool only on rare occasions, or need to provide heating performance that solar panels alone cannot achieve. However, there is no question that the most efficient way to heat your pool is with solar thermal technology, and not solar electricity.