Introduction

This chapter introduces fundamentals of solar feasibility studies as well as engineering design methodologies required to construct and operate a viable and reliable solar power system. The subjects are intrinsically related; the solar feasibility study is to be considered as the initial and perhaps most significant phase of the engineering design.

Shading Analysis and Solar Energy Performance Multiplier

One of the most significant steps prior to designing a solar power system is investigating a location for the platform where the solar PV arrays will be located. In order to harvest the maximum amount of solar energy, all panels (in addition to being mounted at the optimum tilt angle) must be totally exposed to the sun's rays without shading that may be cast by surrounding buildings, objects, trees, or vegetation.

To achieve this objective, solar power mounting terrain and the platform must be analyzed for year-round shading. It should be noted that the seasonal rise and fall of the solar angle has a significant effect on the direction and surface area of the shadows cast.

There are numerous factors to consider when evaluating a site for a photovoltaic or solar thermal installation, and each may impact optimal energy production. In addition to latitude and longitude, which determine the characteristics of the sun's path, panel or collector orientation (tilt and azimuth) defines the field of view that an array has of the sun. Shading from trees, hillsides, buildings, or other obstructions can cause significant degradation in energy production. Additionally, local and regional weather patterns result in site-specific seasonal and daily fluctuations in solar insolation.

These factors combine and interact to determine the solar energy incident on an array and therefore impact both financial returns and customer satisfaction. Tools and techniques used in site evaluation emphasize shade analysis and optimal solar access.

Importance of Site Shading Evaluation

Solar power systems designed with a thorough site evaluation lead to better system designs that will result in the following benefits: increased energy production by selecting the best location for the solar array; improved accuracy in energy production estimates as a result of better quantification of shading and other site-specific issues; optimized financial incentives, such as state-specific rebates that adjust for panel orientation and shading; improved system installation and materials cost estimates; and increased customer satisfaction and confidence, which in turn can lead to repeat or referred business.