Photovoltaic Modules Must Take the Heat

Photovoltaic (PV) modules in tandem with other renewable energy technologies have the potential to play a key role in solving the world's inevitable energy crisis. At present, the price of the technology prohibits widespread adoption with the exception of certain applications (e.g., remote power and lighting) or in locations that have enacted incentive programs. The cost has continued to decline, however, and in general, the PV industry has demonstrated an 18% reduction in cost for every doubling of capacity that occurs about every two years. One focus area for cost reduction continues to be robust packaging materials that are required to protect the PV cells for more than twenty years in extreme environments and with direct sunlight exposure. The technical challenge of this cost optimization problem is compounded by the fact that PV cells are designed to absorb almost all incident sunlight, but typically covert less than 20% into electricity. The remaining 80% of absorbed sunlight energy goes directly into heat, meaning that PV modules can be operated at temperatures well above that of the ambient air. Just how hot do PV modules get? This article estimates the typical thermal environment of PV modules deployed in a number of cities and mounting configurations.