Heat Transfer and Alternative Energy Systems Group

Solar Photovoltaic Hot Water System

Overview

A novel solar water heating system was patented in 1994. This system used photovoltaic cells to generate electrical energy that is subsequently dissipated in multiple electric resistive heating elements. A microprocessor controller continually selects the appropriate heating elements such that the resistive load causes the photovoltaic array to operate at or near maximum power. Unlike other residential photovoltaic systems, the photovoltaic solar water heating system does not require an inverter to convert the direct current supplied by the photovoltaic array to an alternating current or a battery system for storage. It uses the direct current supplied by the photovoltaic array and the inherent storage capabilities of a residential water heater. A photovoltaic solar hot water system eliminates the components most often associated with the failures of solar thermal hot water systems. Although currently more expensive than a solar thermal hot water system, the continued decline of photovoltaic cell prices is likely to make this system competitive with solar thermal hot water systems within the next decade.

The Technology Partnerships Division negotiates the licensing of NIST patented inventions, pursuant to the policy and objectives set forth in the 1980 Amendments to the Patent and Trademark Laws (Bayh-Dole) Act and the Federal Technology Transfer Act of 1986, as amended. Parties interested in licensing an issued patent or patent application to conduct further research on and/or commercialize NIST technology can obtain a license application on-line or from Technology Partnerships licensing officers, or by contacting Mr. Terry Lynch at 301-975-2691.