Focusing the sun a myriad times — that's the aim of solar hyper-concentrators. These devices focus high intensity sunlight on a small area, usually with Fresnel lenses or mirrors. The newest concentrators are a competitive power source, rivaling other up-and-coming renewable energy systems. Some devices are capable of achieving a sunlight concentration equivalent to hundreds of suns.
The Stirling Solar Energy technology (see above) converts thermal energy to electricity by using a mirror array to focus the sun’s rays on the receiver end of a Stirling engine. The internal side of the receiver then heats hydrogen gas, which expands. The pressure created by the expanding gas drives a piston, crank shaft, and drive shaft assembly much like those found in internal combustion engines but without igniting the gas. The drive shaft is connected to a small electricity generator. The entire energy conversion process takes place within a canister the size of an oil barrel.
Entech has a patented concentrator technology which allows for the installation of massive solar "farms" with reduced requirements for solar cell materials (silicon or multi-junction).
Due to the advantages of Entech's concentrator, only 5% of the amount of silicon used in flat plate solar modules is required by current Entech modules to generate the same electrical power. For example, 50 kilowatts of solar cells used in conventional flat plate solar modules generates one megawatt of electrical energy using the Entech modules. Entech concentrators utilize a two-axis tracker to follow the sun's position throughout the day, maximizing energy production.
The funding at SolFocus, which complements a seed round of $3.5 million in March, will be used to test and ramp up production of SolFocus' concentrators and to hire more people, said Gary Conley, the company's founder and CEO. Nanosolar, has raised about $100 million to build a plant to make solar cells from CIGS (copper-indium-gallium-selenium). SolFocus' concentrators magnify the light 500 times, which Conley called the "sweet spot" between higher energy production and excessive heat. The products are aimed at the commercial market, such as retail stores or office parks. SolFocus also intends to build large-scale power generation, where a field of panels could generate several hundred megawatts of power, Conley said.
The company intends to have a 100-megawatt manufacturing facility in India operating at the end of next year, he said. SolFocus then intends to replicate that plant in China, Europe and somewhere in the Americas.