The material and processing costs are still the major drawbacks of the c-Si based photovoltaic (PV) technology. The wafer cost comprises up to 35-40% of the total module cost. New approaches and system designs are needed in order to reduce the share of the wafer cost in photovoltaic energy systems. Here we explore the horizontally staggered light guide solar optics for use in Concentrated Photovoltaic (CPV) applications. This optical system comprises a lens array system coupled to a horizontal light guide which directs the incoming light beam to its edge. We have designed and simulated this system using a commercial ray tracing software (Zemax). The system is more compact, thinner and more robust compared to the conventional CPV systems. Concentration levels as high as 1000x can easily be reached when the system is properly designed. With such a high concentration level, a good acceptance angle of + -1 degree is still be conserved. The analysis of the system reveals that the total optical efficiency of the system could be as high as %94.4 without any anti-reflection (AR) coating. Optical losses can be reduced by just accommodating a single layer AR coating on the initial lens array leading to a %96.5 optical efficiency. Thermal behavior of high concentration linear concentrator is also discussed and compared with a conventional point focus CPV system.

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We describe the design of a thermal refocusing method for spaceborne high-resolution imagers where Korsch optical design is usually implemented. The secondary mirror is made of aluminum, a high thermal expansion coefficient material, instead of conventional zero-expansion glass ceramics. In this way, the radius of the curvature can be controlled by means of temperature change of the mirror. Change in the radius of curvature also changes the effective focal length of the camera which is used for compensation of the defocus that occurred in space. We show that the 30 μm despace of the secondary mirror in the optical system can be compensated by an ∼10°C temperature change of the mirror while the image quality is maintained.

Concentrated photovoltaic (CPV) systems have proven to be an important alternative to conventional crystalline silicon and thin film photovoltaic (PV) energy conversion systems. In CPV systems, lenses or mirrors are used to collect sunlight from a large area and to focus it onto a small area of a high efficiency photovoltaic cell. In this paper, we report the realization of a new CPV concentrator that is based on a horizontally staggered light guide system with a medium concentration level. The optical components were manufactured using a low-cost method, with PMMA as the optical material. Laser-grooved buried-contact silicon solar cells were used and these cells are specially designed and fabricated for this application to minimize the optical and electrical losses. A complete mini-module with a 15 cm x 15 cm area was assembled and tested under outdoor conditions. The test results are in good agreement with the expectations and the main problems causing losses are identified to further improve the system. It is shown that an optical efficiency of higher than 80%, leading to a module power that exceeds 170 W/m 2 , is attainable with existing Si solar cell technology with cost effective manufacturing methods.

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