ArcSol Technology Meets CPV Challenges

The cost-effective deployment of CPV technology faces a number of challenges that arise from its use of tracking high-concentration optics. Whereas the challenges are well understood, the solutions will likely remain an area of active research and development far into the future. ¹

The ArcSol^TM Panel takes a very different approach to addressing these challenges than is seen in the types of CPV systems that are most widely deployed and extensively tested. ArcSol attempts to "design out" several of the problems in conventional approaches by simultaneously miniaturizing and integrating the tracking and optics systems within modular array elements whose geometry maximizes light capture and concentration efficiency.

Challenge	ArcSol Solution
Light capture efficiency	Plane-tiling optics profile shape and center-pivot perimeter mount provides Array aperture coverage of more than 97 percent throughout solar tracking range of 120º degrees about both axes
Optical efficiency	One-bounce reflective focusing No secondary reflector subjected to high flux No obstructions within reflector aperture
Thermal management	Group III-IV cells: Process light from small -- 24 cm² -- apertures whose maximum flux is 2.4 watts Are distributed around thermally-conductive reflector body
Tracking accuracy	Self-orienting No-calibration CPV elements: Use reflector-embedded PV cell illumination to track Eliminate error-introducing linkages between sensors and optics
Soiling, wind-loading, moisture, UV-accelerated aging	CPV array is enclosed in a sealed, UV-screening enclosure that functions in a fixed low-profile position Small, modular CPV elements enable high-volume parallel accelerated life testing
Reliability	CPV elements are mechanically independent and electronically isolating: Failures have only incremental performance impact Elements are easily replaced
Cost	Identical modules consist of a simple six-part assembly plus electronics: Five parts are injection-molded plastic Reflector is stamped aluminum part that doubles as heat sink Assembly can be easily automatable

The first challenge -- maximizing light capture efficiency -- is not frequently addressed in discussions of CPV technology, perhaps because land-use cost is a small factor in today's utility-scale CPV installations. However, in systems that miniaturize CPV arrays to fit in panel-like enclosures, the arrays' light-capture efficiency becomes a performance factor on par with optical efficiency.

1. Opportunities and Challenges for Development of a Mature Concentrating Photovoltaic Power Industry, NREL.gov, Jul 19, 2010, http://www.nrel.gov/docs/fy10osti/43208.pdf