Energy Demand Based Procedure for Tilt Angle Optimization of Solar Collectors in Developing Countries

Abstract

For efficient performance of photovoltaic (PV) panels and flat-plate solar collectors, one of the most important factors that should be considered is tilt angle. The common approach used by researchers has been to calculate the tilt angle (Ss) which maximizes the amount of solar radiation received by the collector. Economically, solar systems must provide maximum energy to the customer not to collect maximum solar radiation. In some situations, there is a mismatch between them. However, solar harvesters need to be tilted at the correct angle to maximize the performance of the system. In this paper, the average monthly solar fraction of the system (the fraction of energy that is supplied by solar energy) is used as an indicator to find out the optimum tilt angle (Sf) for a solar system. This manner is profitable for most developing countries where there is no law governing the exchange of energy between the main provider of electrical energy in the country (in our case the general electrical company) and investors in the solar energy (for example, house owner). Regardless, that the solar radiation in the case optimum tilt angle based upon the maximum solar radiation collection (Ss) is 4% greater than that of the offered tilt angle (Sf), but we get an improvement in the solar fraction coefficient reached to 0.31%, which is equivalent to a yearly sum of 540 MWh. The solar radiation is calculated using the clear sky ASHRAE model and then multiplied by a magnification factor to meet most of the energy demand. This factor is physically presenting the solar conversion efficiency multiplied by the area of the solar collectors. Having the total monthly energy demand, the monthly solar fraction coefficient can be calculated by dividing the total monthly energy delivered by the solar system by the total monthly energy demand.