Design of dual-curvature mirror for linear medium concentration photovoltaic systems

The impact of mirror shape on energy production in Skyline Solar's reflective trough medium concentration photovoltaic system is reviewed using a combination of commercial and proprietary modeling tools. For linear concentrators, an important parameter for efficiency optimization is the uniformity of the flux line on the photovoltaic cells. A significant source of nonuniformity is the discontinuity of reflected light due to the gap between mirrors along the length of the trough. Standard concentrating solar power trough mirrors have a typical length of 1.5 m with a gap between mirrors of 10 to 20 mm. To reduce nonuniformity of the flux line due to this mirror to mirror gap, Skyline Solar developed a dual curvature mirror that stretches the flux line along the trough axis. Extensive modeling and experiments have been conducted to analyze the impact of this design. The methodology of optimization is presented for the X14 Skyline system architecture, and benefits of up to 3% of energy can be realized at locations with latitude below 30 deg.