Solar Photovoltaic Tilt Angle Optimization in the United States

Date of Award


Degree Name

M.S. in Mechanical Engineering


Department of Mechanical and Aerospace Engineering


Rydge Mulford


As global energy demand increases so does the need for renewable energy. Solar energy will play a major role in the fight against climate change and meeting the worlds increasing energy demand. Therefore, it is important to study how solar photovoltaic (PV) production can be optimized. Studies have shown different methods for determining the optimal tilt angle for a fixed PV array all around the world, however the United States remains largely unexplored in this regard. This thesis aims to find the optimal tilt and maximum energy output of PV arrays for every county in the United States. By simulating energy production through the use of open-source material, the results show that states in the southwestern region of the United States produce the most amount of energy annually and have the lowest optimal tilt angles. Tilt angles in this region can be as low as 24 degrees, while states in the northern region of the United States had the highest optimal tilt angles, which could be as high as 42 degrees. This thesis provides the applications used for finding the optimal tilt and energy output. Another important consideration for increasing PV panel energy production is the use of tracking arrays. Tracking arrays dynamically track the sun throughout the course of the day, but tracking technology includes additional capital costs and is not affordable for residential systems. This thesis explores the use of a bi-annual fixed tilt array, where the tilt angle of the fixed array is changed at two times in the year to better capture the seasonal variation in solar irradiation. Optimization techniques are used to resolve the ideal tilt angles as well as the optimal time to change between these two angles for every state in the continental United States. Biannual arrays are then compared to fixed tilt and 1D tracking arrays while examining local weather variations and their effect on the optimal PV tilt angle and solar PV production. In general, PV panels with a fixed tilt in states at higher latitudes collect 90% of the energy that a 1D tracking array would collect, whereas bi-annual tilt angle array produce on average 97% of the energy that a 1D tracking array collects, making the bi-annual tilt method nearly as effective as 1D tracking at these latitudes. Fixed tilt arrays in the southern United States collect on average 85% of the energy that a 1D tracking array would collect, whereas bi-annual tilt arrays in the southern United States produce at maximum 90% of the energy that a 1D tracking array produces. Nearly all states optimize energy production when the tilt angle is changed during the month of March and the month of August. This thesis also examines the relationship between summer and winter temperatures and cloud cover, and their effect on optimal tilt and overall PV performance.


Energy, Engineering, Mechanical Engineering, solar photovoltaics, tilt optimization, United States, bi-annual tilt optimization, seasonal tilt

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