Massachusetts Institute of Technology (MIT)

The use of flat-panel solar photovoltaics (FPV) is growing dramatically as costs decrease. By contrast, more efficient concentrated PV systems (CPV), which focus direct sunlight onto a single point, have not been widely adopted because of their high cost, large size, and expensive tracking systems. A new approach, micro-scale concentrated photovoltaic systems (micro-CPV), may deliver the cost and size benefits of conventional FPV systems, but with an estimated 50% performance improvement. Micro-CPV modules would use cost-effective trackers and generate more electrical power in a given area. This allows installation on space-constrained residential rooftops and decreased costs for commercial and utility applications. Finally, the MOSAIC systems would have the ability to capture both direct and diffuse sunlight, which could make CPV economical in more geographical regions. These innovations could spur the expanded use of PV to generate clean, renewable energy.

The Massachusetts Institute of Technology (MIT) with partner Arizona State University will develop a new concept for PV power generation that achieves the 30% conversion efficiency associated with traditional concentrated PV systems while maintaining the low cost, low profile, and lightweight of conventional FPV modules. MIT aims to combine three technologies to achieve their goals: a dispersive lens system, laterally arrayed multiple bandgap (LAMB) solar cells, and a low-cost power management system. The dispersive lens concentrates and separates light that passes through it, providing 400-fold concentration for direct sunlight and 3-fold concentration for diffuse sunlight. The dispersive lens is a thin layer consisting of inexpensive, lightweight materials that can be manufactured at low cost using plastic molding, an improvement over traditional methods. The lens focuses the direct light onto the array of LAMB solar cells, while also focusing the diffuse light onto common PV cells integrated beneath the LAMB array. The power management system combines power from multiple cells into a single output so that the power from a panel of LAMB arrays can be processed with grid-interface power electronics, enabling as much as 20% additional energy capture in applications where the roof is partially shaded.

If successful, innovations from MIT’s project may lower the cost of solar systems by allowing economical, high-volume manufacturing of micro-CPV arrays. Improved systems could encourage greater adoption of solar power in all three primary markets – residential, commercial, and utility.