Abstract
A detailed research study was performed on the annual energy received by a fixed-tilt solar collector. A new clear-sky model of solar radiation was developed by combining existing clear-sky models with a unique algorithm. This model was then used to perform tilt angle optimizations with two different objectives. The first objective is to achieve the maximum annual solar energy received by a solar panel, while the second is to balance the energy received so that it is more uniform over the course of a year. Each of these objectives has differing optimum tilt values, depending on the location and usage of a solar collectorsystem. The novelty of this investigation is the use of the aforementioned solar model for multiple optimizations for these two different objectives, which results in two different optimum tilt angles that are in turn different from the widely accepted rule-of-thumb that recommends an angle that is equal to the latitude. The solar radiation results obtained with the model used herein were experimentally confirmed through comparison with measured weather data for a number of locations with different sky-clearness indexes as well as compared with other studies found in the literature. A major contribution of this study is the plots and tables showing optimum tilt angles as estimated by the model as well as with empirical data. By selecting the appropriate tilt angle, a designer can now decide to either maximize annual energy received or else balance energy delivery over the year.
