Study of hourly site-pair correlations of the clear-sky index and its predictor variables for long-term resource planning of solar cities

Abstract

‘Solar City’ plans are being promulgated to reduce cities’ dependence on conventional fossil fuel-based power. Variability of solar radiation is a critical issue for these solar city plans. This paper aims to study this crucial issue by studying hourly site-pair correlations of clear-sky index variation and their underlying factors within a city. The analysis has been conducted for eight Indian cities, which have been proposed as prospective solar cities by the Government of India. The underlying factors taken into consideration are distance, relative humidity, wind speed, and temperature. Principal component analysis and regression analysis have been conducted to find the relationship of the site-pair correlations of clear-sky index with the identified predictor variables. The results show that though the underlying model remains predominantly similar across cities and zones, the predictor variables and the degree of fit change depending upon the local geographical and climatic peculiarities of various cities and regions.