Link to document:
Status
Electronic Resource
Call number
Publication
JPL 5101 45; Report; December 1977.
Language
Library's review
ABSTRACT:
Solar photovoltaic arrays deployed in certain areas of the U.S. will be subject to damaging hailstones. Hailstones up to five inches in diameter have caused damage to glass panes in buildings and autos, to asphalt roofs, and to other property and crops.
This report presents the results of a
A key element of this study involves the generation of a statistical model describing the probability of impact by hailstones of various sizes and estimating the mean time between hits. This model is based on three types of information: the average number of annual hail days at a location; the hailstone size distribution, given that a hailstorm has occurred; and the areal densities of hailstones. Hail statistics in each of these areas are developed from published hail records and private consultation with experts in the field. The general lack of good quality data, particularly on hailstone size distribution and areal densities, necessitates extrapolation of sparse data and leads to large uncertainty bounds on the final results. These uncertainty bounds are analyzed via a sensitivity analysis in which the size and areal density distributions are allowed to vary between maximum and minimum values as determined from available data. This provides a range of values for the study result which are stated in terms of the probability of a given area of solar array being struck by hailstones of a specific size or larger. The results are identified by region, and are defined in terms of the number of annual hail days associated with that region. The results indicate that damage to solar collectors from hailstones may occur in many parts of the country. In the Great Plains region of the United States, where the most damaging hail occurs, it is predicted that solar arrays will be struck by hail stones 1.5 inches or larger as often as every 6 to 8 years. Although these results contain considerable uncertainty, it is concluded that the local hail environment of a proposed site location is an important factor to consider in solar array design and applications. This is particularly true considering the large site-to-site variations even within small regions of the country.
Solar photovoltaic arrays deployed in certain areas of the U.S. will be subject to damaging hailstones. Hailstones up to five inches in diameter have caused damage to glass panes in buildings and autos, to asphalt roofs, and to other property and crops.
This report presents the results of a
Show More
study assessing the probability of solar arrays being struck by hailstones of various sizes as a function of geographic location and service life. The study complements parallel studies of solar array sensitivity to hail damage, the final objective being an estimate of the most cost effective level for solar array hail protection.A key element of this study involves the generation of a statistical model describing the probability of impact by hailstones of various sizes and estimating the mean time between hits. This model is based on three types of information: the average number of annual hail days at a location; the hailstone size distribution, given that a hailstorm has occurred; and the areal densities of hailstones. Hail statistics in each of these areas are developed from published hail records and private consultation with experts in the field. The general lack of good quality data, particularly on hailstone size distribution and areal densities, necessitates extrapolation of sparse data and leads to large uncertainty bounds on the final results. These uncertainty bounds are analyzed via a sensitivity analysis in which the size and areal density distributions are allowed to vary between maximum and minimum values as determined from available data. This provides a range of values for the study result which are stated in terms of the probability of a given area of solar array being struck by hailstones of a specific size or larger. The results are identified by region, and are defined in terms of the number of annual hail days associated with that region. The results indicate that damage to solar collectors from hailstones may occur in many parts of the country. In the Great Plains region of the United States, where the most damaging hail occurs, it is predicted that solar arrays will be struck by hail stones 1.5 inches or larger as often as every 6 to 8 years. Although these results contain considerable uncertainty, it is concluded that the local hail environment of a proposed site location is an important factor to consider in solar array design and applications. This is particularly true considering the large site-to-site variations even within small regions of the country.
Show Less