(408) 432-9900

Is Solar Thermal Now Cost Competitive with Natural Gas Heat and Hot Water for Apartment Buildings? Yes


A 3-story, 19,260 sq. ft. renovation project, located at 1731 15th St in San Francisco, will serve as a 50 one-bedroom student apartment complex located near the Mission Dolores section of San Francisco. In the background is a solar PV project on another building.

Is solar thermal now cost-competitive with natural gas heating and hot water for apartment buildings? As Free Hot Water recently found out, the answer is… yes! 

One of Free Hot Water’s new clients, Barak Jolish, a San Francisco building developer, revealed to us that he had received a total of five bids to install a new hydronic radiator heating and hot water system for his 3-story, 50-unit student housing renovation. He received four natural gas-based bids for a combined heating and hot water natural gas system. Then, on a friend’s referral, Jolish asked Free Hot Water to submit a design for a solar thermal based hydronic heating and domestic hot water system with a natural gas back-up.

Free Hot Water won the bid, but it was only later when Jolish revealed to us that our design not only met his energy efficiency goals, but that the project was also about the same $200,000 price–or less–than the four earlier natural gas-based bids he’d received, and that cost was before applying any state or federal solar incentives. After California’s CSI Thermal incentive and other Federal tax incentives, Jolish’s net cost was around $114,000. Even more impressive was the fact that Free Hot Water’s design also included a 4.5kW solar PV system to offset the building’s electricity and solar water heating pump stations.

Jolish is a real-estate developer with 17 properties in San Francisco, and he said that while he appreciates green energy, his primary goal was to get his renovation under budget and reduce his operating costs. That Free Hot Water’s design was based on solar technologies was besides the point.


A photo of the 3-story, 19,260 sq. ft. renovation project, located from the street view. Free Hot Water’s design also included energy efficiencies, a 4.5kW solar PV system, and a web-based dashboard that monitors all of the building’s heating, hot water, and solar thermal systems, as well as back up systems.

18 4 X 10 made-in-USA OG-100 certified solar collectors will provide 750 gal/day of solar hot water for tenants’ showers, laundry, and dish washing, as well as fuel the hydronic radiator heating system. 95% gas boilers will back up the solar at night and cloudy days. In addition to the upfront savings, Jolish estimates that the building’s solar systems will be cutting its operating energy costs by 66%.

While this is just one renovation project in California, chief engineer Gal Moyal says that Free Hot Water’s same proprietary design and engineering could be applied to any new multi-unit housing construction project or to a replacement heating and hot water project.

“This is groundbreaking news,” Moyal said, “We had no idea that solar thermal was so cost competitive with conventional gas heating systems until Mr Jolish revealed his other bids to us after our work had started. From now on, even without incentives, you can choose solar thermal systems and save money on operating costs.”

This entry was posted in 30% Investment Tax Credit, CSI Thermal Program, Solar Hot Water for Apartment Buildings. Bookmark the permalink.

Comments are closed.