A new polymer-based solar-thermal device developed by Wake Forest University is the first to generate power from both heat and visible sunlight, an advance that could shave the cost of heating a home by as much as 40 percent.

Geothermal add-ons for heat pumps on the market today collect heat from the air or the ground. This new device uses a fluid that flows through a roof-mounted module to collect heat from the sun while an integrated solar cell generates electricity from the sun’s visible light.

Unlike the flat solar cells used today, the curve of the tubes inside the new device allows for the collection of both visible light and infrared heat from nearly sunrise to sunset. This means it provides power for a much greater part of the day than does a normal solar cell.

A standard, rooftop solar cell will miss about 75 percent of the energy provided by the sun at any given time because it can’t collect the longest (infrared) wavelengths of light. Such cells miss an even greater amount of the available daily solar power because they collect sunlight most efficiently between 10 a.m. and 2 p.m.

The design of the new solar-thermal device takes advantage of this heat through an integrated array of clear tubes, five millimeters in diameter. They lie flat, and an oil blended with a proprietary dye flows through them. The visible sunlight shines into the clear tube and the oil inside, and is converted to electricity by a spray-on polymer photovoltaic on the back of the tubes. This process superheats the oil, which would then flow into the heat pump, for example, to transfer the heat inside a home.

Tests of the solar-thermal device have shown 30 percent efficiency in converting solar energy to power. By comparison, a standard solar cell with a polymer absorber has shown no greater than 8 percent conversion efficiency.

The research team will build the first square-meter-size solar-thermal cell this summer, a key step in getting the technology ready for market.

Hmm… maybe the Arizona State University researchers should talk with their Wake Forest University counterparts about using graphic nanoparticles in this device?