Solar water heaters are a popular and widespread technology, but they’re not right for every rooftop. If your house points in the wrong direction, you’re out of luck.
That’s why Alex Pina has developed a new type of heater that tracks the sun. Looking like a mirrored satellite dish, he hopes it will enable more people to heat water using the sun’s rays.
“We follow the sun as it moves across the sky, which enables homeowners to place the system wherever they like,” he says. “You’re no longer restricted to south-facing roofs for good solar energy. Now you can put it on the north-facing roof, or on the ground in your backyard.”
The unit focuses light in a two-step process: first through a “primary reflector” then concentrating it down to an beam that directly heats water. Solar thermal systems are used widely in utility-scale projects, but not normally on rooftops or outside deserts.
Pina’s company Avalanche Energy is developing the unit at Greentown Labs, a Massachusetts incubator. He claims it will save home-owners $300-$400 a year compared to a conventional electric heater, as long as he can bring the price down to his goal of $2,000 (or $1,000 after incentives and subsidies in the New England area).
The dishes, which are all-aluminum, are four-by-four feet across, or 16 square feet. They incorporate a GPS locator and sensors so the unit knows where it is in the sun’s cycle and can point in the optimal direction. It also has a miniature solar panel to provide power to run a DC-motorized tracking system.
Pina first developed the idea after seeing his grandparents trying to install a solar forced-air system in their house. They weren’t able to put something on their roof, because the sun was shining the wrong way.
Avalanche has created two prototypes and plans a final version to be tested this summer. It hopes to market a full product next summer. Pina points to the system’s simplicity: the unit is mostly metal, has no glass, and doesn’t use a chemical (like glycol) to help retain heat in the coils.
We’ll have to see if the unit survives harsh East Coast winters, but Pina is optimistic. “If we can make it work in Massachusetts and make good returns, we know it will work better anywhere else,” he says. “We’ll start with the hardest place and everything gets easier from there.”