But heat and dust can cause durability problems in the typical “lens-box” CPV designs, where dust can leak past seals and accumulate internally where it cannot be cleaned. Heat and condensation in lens systems can also degrade the optical performance of lenses, which typically are a combination of glass and silicone.
NEW IMPLEMENTATION OF CPV
The SST CPV design reduces these problems by using a mirror to concentrate the light externally to a more compact Receiver with 12 CPV modules. Each CPV module accepts about 200-400-times concentrated sunlight from the dish mirror collector, and so it is about 200 times more compact than “lens-box” CPV modules. It can be better sealed and protected against dust, water and heat. All of the optical surfaces are glass or quartz for durability. The SST mirror panels use thin-glass mirrors, with proven performance and durability. In the future, non-glass reflectors can be considered and used with the SST mirror panel, when they provide advantages.
Because of the high efficiency of CPV cells, currently exceeding 40%, less land area is required per megawatt. Dishes are arranged with about 75% of the land as “open space” between units to minimize shadow losses. At a 12 kW rating this provides over 500 kW per hectare (10,000 m2), or 5 acres per megawatt, assuming nominal spacing between dishes.
The target power rating per dish will increase over time. With pre-production fabrication methods and current CPV cell efficiency (42%), the power output is expected to be 10 to 12 kW. As the manufacturing is brought to full commercial status the power output is expected to reach 15 kW. Future CPV cell efficiency has potential to exceed 50%. With improvements in CPV cells the Dish-CPV system is expected to increase to 16 kW in the near term, with up to 20 kW possible over time. This long term efficiency goal could provide nearly a MW per hectare, or less than 3 acres per MW.