On the relation between insolation and climatological variables—IV. Construction of a model year of solar intensity and climate

Abstract

Proper design and sizing of a solar energy heating and/or cooling system involves an assessment of the local availability of solar energy and its relationship to local climate.

A study is made of availability of solar energy at Fort Hood, Texas for the period 1961–1969. Hourly values of climatological variables were obtained from the National Climatic Center. These are combined with correlations of solar intensity with cloud cover and visibility to obtain hourly estimates of total insolation and normal incidence solar intensity. Monthly totals are calculated for each of the 108 months in 1961–1969, and average monthly solar intensities are obtained. For each month of the year, the month in the 1961–1969 period that most closely approximated the average solar intensities, as well as the average heating and cooling degree-days, is chosen to prepare an average model year. This average has hourly values of solar intensities as well as climatological variables. Hourly models are also prepared for the worst winter and summer months in the period. Finally, a study is made of correlations of solar availability with degree-days. It is found that there is very little correlation in winter, but in summer sunny days are highly correlated with hot days.