Numbers of studies have been carried out on the performance analysis of single and double pass solar air heaters. These studies include the design of solar air heater, heat transfer enhancement, flow phenomenon and pressure drop in duct. In this book, mathematical modeling based on energy analysis for three different configurations of solar air heater namely single pass with one and two covers and double pass have been developed. It was shown that for each collector the energy balance equations of the components of the collector, at quasi steady state, provide a 3×3 non linear differential equation. A code was written to solve the equations by means of finite difference approach using MATLAB software. The effect of the most significant ambient and design parameters such as ambient temperature, mass flow rate and channel height on the performance of each model was investigated and compared to each other.