Laboratory Evaluation of Solar Power Units for Marine Aids to Navigation.

This report describes the Coast Guard evaluation of solar energy as a power source for lighted aids to navigation. Fifty-three solar powered aids, on test in a natural environment at Groton, Connecticut, have been continuously monitored for two years. Solar arrays from two manufacturers were tested with neither being wholly satisfactory. One had major quality control problems while the other suffered from inadequate sealing. Three types of lead-acid batteries used for energy storage have all been satisfactory to date. The test has indicated the advantages of voltage regulation in reducing water use in batteries, but has not proved that regulation is in fact required for long battery life. The insolation measured has shown excellent agreement with that predicted using the averages from a surrogate area. Almost all of the original estimates that were made to predict system performance battery capacity vs. time of year proved to be very conservative and most of the systems performed better than expected. Author