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Daily global solar radiation decomposition models (DGSRD models) are important to solar photovoltaic, solar thermal utilization and building energy assessment. The existing DGSRD models are analyzed with hourly global solar radiation data measured from January 2009 to December 2011 on Jiading Campus, Tongji University. The results show the existing models established in the form of a Gaussian equation are comparatively accurate, followed by models adjusted or modified from the Whillier – Liu & Jordan models, and the Newell model is of the lowest accuracy. Among the existing models, the CPRG model is the most accurate one. Then four new decomposition models of daily global solar radiation (DGSRD model 1 to DGSRD model 4) are established based on consideration of the solar altitude angle, the solar azimuth angle, the solar hour angle, clearness index and temperature. Based on the analysis of correlation coefficient, relative standard error, mean bias error, mean absolute bias error, root mean square error, Nash–Sutcliffe Equation and t-statistic (t-stat), it is demonstrated that new DGSRD models (DGSRD model 1, DGSRD model 2 and DGSRD model 4) are more accurate than those existing ones, in which the DGSRD model 4 is the most accurate one.

Five algorithms for sun position computation, with validity from 2010 to 2110, are proposed and discussed. The algorithms have different accuracy levels, with maximum errors in the solar position spanning from 0.19° to 0.0027°, thus covering a wide range of possible applications. The algorithms are optimized in order to reduce their computational cost as much as possible. The extended time range of validity allows users to employ these algorithms even in long-term projects.

A new design concept, called one axis three positions sun-tracking polar-axis aligned CPCs (3P-CPCs, in short), was proposed and theoretically studied in this work for photovoltaic applications. The proposed trough-like CPC is oriented in the polar-axis direction, and the aperture is daily adjusted eastward, southward, and westward in the morning, noon and afternoon, respectively, by rotating the CPC trough, to ensure efficient collection of beam radiation nearly all day. To investigate the optical performance of such CPCs, an analytical mathematical procedure is developed to estimate daily and annual solar gain captured by such CPCs based on extraterrestrial radiation and monthly horizontal radiation. Results show that the acceptance half-angle of 3P-CPCs is a unique parameter to determine their optical performance according to extraterrestrial radiation, and the annual solar gain stays constant if the acceptance half-angle, {theta}{sub a}, is less than one third of {omega}{sub 0,min}, the sunset hour angle in the winter solstice, otherwise decreases with the increase of {theta}{sub a}. For 3P-CPCs used in China, the annual solar gain, depending on the climatic conditions in site, decreased with the acceptance half-angle, but such decrease was slow for the case of {theta}{sub a}{

A specific class of paraboloidal reflectors namely the offsetfeed paraboloidal reflectors which find application in space communications is utilized for concentration of solar energy at a fixed point (focus) maintained throughout the day in shade. The energy distributions on spherical receiver centered around the focus and on a flat sectorial receiver held in a plane perpendicular to the focal line have been studied for the case of perfect tracking in hour angle and declination axes. The spill-over of energy due to non-tracking in hour-angle or declination axis for specific periods in the case of a flat sectorial receiver has been studied and plotted. A summary of the results and suggested applications of this configuration are presented. A comparison of performance is made between wedge-type and circular aperture type offsetfeed reflectors.

The amount of direct light gathered by a combination of reflector plus flat-plate collector has been analyzed. The calculations were done allowing variable reflector and collector orientation angles, variables latitude, and arbitrary sun hour angle away from solar noon. The effects of reflection and transmission losses and of polarization of the incident light were included. Correction was also made for the finite size of the reflector. It was found that the optimum orientation has the collector plane almost perpendicular to the plane of the reflector. This optimum orientation is approximately independent of the sun's azimuthal dependence. The optimum reflector angle is found to be between 0° and 10° above the horizon for winter solar conditions. For typical winter operating conditions the enhancement in light gathering power for direct solar radiation is about a factor of 1·4–1·7. This results in an effective increase of 100% in the useful winter heat output from a practical reflector-collector combination with a reflector angle of 0°, over the useful heat output obtained with an optimally oriented simple flat-plate collector. An approximate calculation was also made of the overall enhancement in useful heat output for diffuse solar radiation; an increase by a factor of about 1·5 is predicted. Comparison with the preliminary analysis of the performance of the Coos Bay, Oregon solar house shows substantial agreement with the predictions of the present analysis.