Photovoltaics for Buildings: New Applications and Lessons Learned

Sheila J. Hayter, Paul A. Torcellini, and Michael P. Deru, National Renewable Energy Laboratory

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Abstract

Photovoltaics (PV) for buildings system applications are experiencing exponential growth. This increased activity is the result of building owners becoming more confident with this new technology, designers becoming more comfortable incorporating PV into architectural and building electrical designs, decreasing PV system cost, the heightened public awareness of depleting conventional energy resources, and issues related to power reliability and stability. Usually, these systems meet primary objectives to offset building electrical loads, decrease building electrical demand, or provide continuous power supply during utility grid outages; but because of design flaws, installation errors, or improper maintenance, these systems can perform below the design expectations.

Currently, the performance of the PV systems integrated into the designs of three high-performance commercial buildings is under close observation. The rated capacities of these systems range from 7 kWp to 60 kWp. Two systems are roof-mounted systems and one is a roof-integrated system. All systems are grid-tied and one also doubles as the uninterruptible power supply (UPS) system for the building. These systems provide power to a classroom/laboratory building, a national park visitor center, and a retail store. This paper discusses experiences with these PV systems on commercial buildings and presents energy performance and solutions to resolve design and operation issues.