Practical Solar wants to bring solar thermal home, but in a somewhat unusual manner.
The company has created a system for harvesting heat from the sun to heat up a house. It plants heliostats – i.e., metal poles festooned with an array of mirrors – in your lawn or a nearby patch of real estate. The mirrors collect heat and then beam it into your living room.
A computerized control system guides the heliostats to maximize the harvesting of heat.
Although you'd think that something like this might sell best in the South, where it's hot, Practical is mostly targeting New England. It's the region where people need to heat their homes.
Solar thermal water heaters have been used to replace or supplement home water heaters or pool heaters for years. A number of companies – Sopogy, Chromasun, Millennium Solar and others – now want to expand how solar heat can be exploited. Chromasun, for instance, has a device that collects solar heat to run air conditioners. Some other companies use the heat for fluid pipe heating systems.
Cypress Semiconductor and a new crop of start-ups also want to harvest solar (and waste) heat and turn it into electricity with thermoelecttric semiconductors.
Practical cuts out the middle steps and beams that heat as well as sunlight directly into your rooms. A single heliostat provides about 600 watts of thermal energy.
The hardware and real estate requirements are a bit daunting. "You need about 25 heliostats for a home in New England," said CEO Bruce Rohr. It takes about four hours to assemble a system.
That number of heliostats will need about 2,500 square feet of real estate, he added. Additionally, homeowners are advised to also install a 5,000 gallon thermally insulated water tank for storing heat. That tank will heat your house for ten days or so.
A total installation costs about $20,000. With tax credits, it will pay for itself in seven or so years, he said. Unlike solar photovoltaic panels, however, there is no mechanism for selling the heat onto the grid. Thus, heat collected in the summer can't serve to provide credit with your utility, but it can be used to heat water.
Pets, kids and anyone else will also want to avoid standing in the path of the heat bouncing off the heliostat for long too.
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