Estimation of Solar Radiation and Optimal Tilt Angles of Solar Photovoltaic for Khon Kaen University

In order to maximize the output energy of a solar photovoltaic, the surface of a solar panel is required to be perpendicular to the direction of the solar ray. Therefore, a solar tracker is widely used for maximizing the output energy of solar photovoltaic. However, a solar tracker is expensive and not suitable for some locations. Another solution to maximize the output energy of a solar photovoltaic is setting the optimal tilt angles. The advantage of this solution is no additional cost of device but the obtained energy is less than the solution using solar tracker. This work is a systematic approach to find out the optimal tilt angles for Khon Kaen University $\pmb{(\text{Latitude} =16.472^{\circ}\text{N}}$ and Lo $\mathbf{ngitude}=\pmb{102.826^{\circ}\text{E}}$). Calculation and experimental methods are used to find out the monthly, seasonally and yearly optimal tilt angles. For the calculation method, optimal tilt angles were mathematically determined by finding maximum daily solar radiation received by changing tilt angles from 0° to 60° of a 5° per step of change. For the experimental method, optimal tilt angles were determined by setting a 5-W monocrystalline solar photovoltaic for five various tilt angles consisting of 0°, 16°, 30°, $\pmb{45^{\circ}}$ and $\pmb{60^{\circ}}$. The experiment was conducted from March to May. From the results, monthly optimal tilt angles from experiment and calculation methods are nearly the same.