The largest solar water heating project to date in California is scheduled to start this month at a 320-unit condominium community in San Jose called The Tradewinds. The rooftop system being installed is projected to reduce this complex’s water-heating bills by as much as 60%.

Solar thermal “is a 5,000-year-old technology that’s new again,” says Paul Burrowes, COO of Free Hot Water, a locally based manufacturer that designed the systems being installed on five roofs of the two-story buildings in the Tradewinds complex. The systems will heat water to between 130 and 180 degrees and are expected to eventually relegate the buildings’ central boilers and water heaters to backups.

TBI Energy is managing this project, and the design/build mechanical contractor Comfort Energy will do all of the installation, which should take about two months, says Cheryl Butterton, TBI’s project manager. (The project will actually take four and a half months to complete because of California’s metering requirements.) Butterton says this is the largest solar thermal project to receive Pacific Gas & Electric rebates. Using the California Solar Initiative Program as its guide, Free Hot Water estimates that Tradewinds will earn approximately $186,240 in rebates. (Because Tradewinds is a not-for-profit homeowners association, it isn’t eligible for energy tax credits.)

“I feel proud to bring renewable energy and efficiency to The Tradewinds,” said Craig Gorewitz, who manages the complex’s day-to-day activities. He tells Builder that the HOA's out-of-pocket expenditure would be around $390,000, and that the system and its installation would cost a total of about $600,000. Free Hot Water estimates that the HOA should recoup its investment within 2.7 years, ''but we'd be happy if it was five years,'' says Gorewitz.

News about this project was first posted on Renewable Energy World’s website. The companies working on this project did not disclose the cost of the systems being installed.

In an interview with Builder this week, Burrowes explained how his company’s solar thermal system works.

Water comes from the city into buildings at about 55 degrees Fahrenheit. Multifamily structures typically include one central boiler for every 50 to 100 units, and that boiler provides water that’s heated to around 120 degrees. However, the boiler must be on all the time so residents can get hot water when they want it.

Three natural gas central boilers heat water for The Tradewinds’ residents—78% of whom own their homes, and the rest rent—who use about 10,000 gallons per day.

Burrowes says that the solar thermal system will heat water by means of a heat-transfer fluid, propylene glycol, which circulates through what he calls a solar loop, from 183 commercial-grade solar hot-water collectors to a pump station and then through heat-exchange coils that lead to three 2,500-gallon underground storage tanks. The fluid heats the water in those tanks up to 180 degrees, which is then sent, as needed, through other coils to the building’s boiler system.

Free Hot Water estimates that this solar thermal system will produce over 5 million BTUs daily and save more than 250,000 pounds of carbon dioxide annually.

Burrowes says his company has taken a “LEGO-like approach” to designing its systems to make their installation as simple as possible. Philip Neumann, a vice president with Comfort Energy, confirms that “Free Hot Water is doing a lot of the work that we’d normally do,” such as handling the water flow and exchanges.

Neumann says that TBI chose Comfort Energy as its contractor on this project because of its background in hydronics and solar thermal, “which we integrate into a lot of projects we do.” The biggest challenge the Tradewinds installation presented, he said, was the community’s “mature landscaping. We have to work around trees to get equipment in, and trench real carefully.” Free Hot Water also had to design the roof plan around tree shade.

Free Hot Water’s goal is to have distributors in every state in the country. Its website includes a calculator that allows visitors from any state to figure out how much a solar thermal system would cost for their homes or buildings, and what the rebates, tax credits, and cost savings would be.

But its most fertile target right now is California, where buildings must now comply with new regulations aimed at significantly reducing the state’s greenhouse gas emissions by 2020.

In San Jose alone, Neumann believes that “there are so many other complexes” that use lots of water and could benefit from a solar heating conversion, including health clubs, assisted living facilities, and laundromats. Neumann adds that solar thermal systems are “much more efficient” when energy storage is on-site, bringing these systems’ sunlight-to-end user efficient beyond 70%, compared to the 17% to 18% efficiency of photovoltaic cells.

But pitching energy efficiency is never the easiest sell in the world: Burrowes says he negotiated with the residents of The Tradewinds for nine months before they agreed to allow the solar thermal installation.

John Caulfield is senior editor at Builder magazine.

Learn more about markets featured in this article: San Jose, CA, Los Angeles, CA.