A SIMPLE METHOD FOR REPRESENTATION OF SOLAR RADIATION AND WEATHER DATA FOR DESIGN PURPOSES

I. Segal, A. Arbel, D. De Thysebaert
Designers of solar systems need to evaluate the two most important weather parameters: solar radiation and ambient temperature.

A friendly computer program, to be used with a Personal Computer, was developed to simulate the clear sky radiation and the ambient temperature at required intervals.

  1. Clear sky radiation The required data are the location of the site, the dates, geometrical parameters (slope and orientation), and time interval for the calculations.

    An example of a computer calculation is presented. The results are compared to measurements made at Bet Dagan, Israel, and show, as expected, that calculated radiation is slightly higher. The ratio KT between measurements and calculated results could be used for summer simulations with very small error. For the winter months, this error is more significant due to the existence of cloudy days. For this period, we propose another method of representation utilizing radiation values of two types of days: clear sky and very cloudy days.

  2. Ambient temperature The same program included a simulation of the ambient temperature. The required data are the yearly mean temperature and the yearly mean amplitude of temperature variation around this mean. This simulation is based on sinus variation of the temperature throughout the year and during the day. We assumed that the times of occurrence of the daily maximum and the daily minimum are constant along the year. This simple method produces a temperature variation with good correlation with respect to the daily mean. The hourly variations representation is less satisfactory.
Segal, I., Arbel, A. and De Thysebaert, D. (1989). A SIMPLE METHOD FOR REPRESENTATION OF SOLAR RADIATION AND WEATHER DATA FOR DESIGN PURPOSES. Acta Hortic. 245, 363-369
DOI: 10.17660/ActaHortic.1989.245.48
https://doi.org/10.17660/ActaHortic.1989.245.48

Acta Horticulturae