Solar thermal technology — a.k.a. solar water heating — is popular in homes and businesses in Mediterranean climate zones around the world, yet it's oddly scarce in similarly sunny Southern California. That could soon change.
Thanks to today's eco-conscious mentality, not to mention the draw of lowered utility bills and a state rebate program to incentivize solar thermal system installation, more and more SoCal denizens are discovering the many benefits of solar water heating.
Solar water heating is found in more than 90% of homes in Israel, where heating water with rooftop solar collector plates was invented in the early 1950s. It's also common in countries such as Cyprus and Greece. But the U.S. has lagged far behind in implementing this common-sense, cost-effective and sustainable technology — only about 30,000 solar water heaters were being sold nationwide annually as of 2013, according to a report by the nonprofit trade group Solar Energy Industries Association.
Solar water heating systems pump fluid through a device called a heat exchanger, which then transfers the solar energy gathered by the roof-mounted, often tube-shaped collectors to the hot water flow of a building. According to the U.S. Department of Energy's website, installing a solar thermal system can reduce a user's water heating bills by 50% to 80%.
Boosting the efficiency and supply of an existing water heater with a solar thermal system can be particularly significant for commercial users that require a lot of hot water, such as hotels, multi-family property management companies, and restaurants. And if a business grows and its need for hot water increases, a solar water heating system can keep pace, with little modification. Additionally, factoring in applicable federal, state and local tax incentives, a rebate of up to $800,000 per site is available from the California Solar Initiative Thermal Program for commercial customers.
UCLA, where solar water heating helps power 5,000 showers and 7,000 meals per day, has offset up to 80% of its water heating costs, according to a report on SoCalGas.com. The university is saving more than $3,600 per year on natural gas in just a single residence hall.
San Diego-based architecture firm Carrier Johnson + Culture recently incorporated a solar thermal system into a large student housing project at UC San Diego. The system meets 90% of the project's residential hot water demand.
The firm's design called for collectors to be mounted on various roofs and canopies above exterior walkways. Those collectors absorb the sun's rays, and the heat energy is transferred to a non-potable fluid that's piped down to heat exchangers that warm the separate potable water system.
While multiple types of solar water heaters exist, three in particular are fairly popular and widely available, explained Brooke Nally, content coordinator at SolarPowerAuthority.com. Batch collectors heat water within an insulated box and store it until needed. Flat-plate collectors consist of copper tubes fitted to an absorber plate. Evacuated tube collectors capture solar energy in vacuum-sealed glass tubes and are the most efficient and popular contemporary choice.
"Although solar water heaters have been around for a long time … we have seen significant technological advancements [in the past 10 years]," Nally said. Between those advances, state incentives, an available 30% federal tax credit and the systems' 20-plus-year lifespan, she said, today's solar water heaters can be well worth the long-term investment.
That means now might be the best time for SoCal businesses to start catching some rays.
—Tribune Content Solutions for SoCalGas