The size and cost of a solar PV system for a government building or public works project depends on the unique energy needs of each site.

The size is determined by an assessment of a building's total energy usage over one year and not by square footage. A SPG Solar, Inc. (SPG) energy consultant visits a facility site, analyzes a year’s worth of electric utility bills, and submits a free energy use assessment to the client.

SPG then provides a solar system proposal with a design based on actual and projected energy needs. SPG-designed solar systems maximize the return on investment (ROI), and are not necessarily designed to put the most amount of solar possible on the roof. Current rebates available subsidize the total cost of the solar system by anywhere between one-third and 40%.