DEFINITION OF OPTIMUM ANGLE OF INCLINATION OF SOLAR COLLECTOR DEPENDING ON ITS ORIENTATION AND PROBABILITY OF SUNSHINE

Abstract

A method of determining the optimum angle of inclination of a flat solar collector to the plane of the horizon, depending on its orientation and the probability of sunshine in the area of construction, is developed.

The curves of maximum (astronomical) and statistical duration of sunshine in hours for Sarny city of Rivne region are given. These curves depend on the number of the year day. The probability of sunshine is also shown depending on the day of the year. This curve was calculated as the ratio of the statistical sunshine duration to the maximum.

The statistical duration of sunshine was taken from the observations of an actinometric station in Sarny city and the maximum duration was calculated in the program developed by the authors.

Also there is surface of incoming solar radiation in one square meter depending on the orientation and angle of inclination of the plane of the solar collector to the plane of the horizon. The shape of this surface gives a clear idea of this dependence, but is inconvenient for practical use.

The surface itself is formed from curves of dependence of energy supply on one meter square of the collector plane from the angle of its inclination to the plane of the horizon. These curves were calculated for ten collector orientations. The orientation varied from south to east in ten degree increments.

All curves have one maximum. This made it possible to build the optimal curve collector angle to the plane of the horizon from its orientation.

For comparison, a similar curve was shown. But it was built without taking into account the probability of sunshine. This curve illustrates the substantial dependence of optimal angle of the probability of sunshine (optimally be much greater angles).

The method can be used (if statistics are available for the construction area) for other periods of the year, for example, spring-summer-autumn, given that in certain areas of construction snow may lie on the collector planes for a long time. Other periods of the year may also be used for climate-related reasons, such as electricity schedules.

Keywords: flat solar collector, astronomical and statistical duration of insolation, the probability of sunshine, optimum tilt angle, integral atmospheric transparency coefficient, orientation of the solar collector, mass of atmosphere.