Assess the site for solar access
Solar access can be determined at a basic level by visually identifying areas that avoid shading or blockage of sunlight from adjacent trees or buildings. Solar access of a location can be measured using a sun path diagram that simulates the sun’s path across the sky. Many solar designers and installers have this or a similar measurement tool; local utilities or energy organizations may also have them available to borrow or rent. NOTE: In North America, the best location for solar panels is south-facing. Generally, never consider placing them on a north-facing roof.
The site being considered must have good solar access since even a small amount of shading can affect the whole system’s output negatively. If possible, consider more than one location to evaluate further. Collect general data about the building, such as square footage, roof condition, roof pitch, any existing building plans like structural designs, etc. This information will come in handy when you speak with solar design professionals and your local utility.
Some states have easement or other laws that govern solar access. Check with the local building department to determine if it’s possible to limit or prohibit neighboring properties to develop in a way that would decrease the solar access of the proposed installation site. Any additional permitting and environmental compliance requirements should be researched at this time as well. Any time delays or additional cost associated with permitting should be factored into the overall feasibility, timeline and scope of your project.
Evaluate the solar resource
The second item to consider when developing a solar project is the source of solar – how much sunlight the organization typically receives a day. One of the easiest resources to help you is the National Renewable Energy Laboratory (NREL) PV Watts Calculator. The online calculator uses weather data near any address to determine how many hours of sun is expected based on latitude, longitude and average weather patterns.
This tool allows a user to input a pre-determined amount of solar electricity (in kWdc) based on electricity needs, or to draw a system on a Google aerial image of the proposed site.
Drawing a system is an easy way to calculate the approximate system capacity that will fit on any building or land, or to calculate the approximate amount of space the pre-determined system will occupy.
The tool provides an output of estimated kilowatt hours that the system is expected to produce per year. This information can then be used when completing your financial assessment. Note that the tool includes some basic economic analysis capability. However, in general, the economic calculation included in the tool is not sufficient to understand the economic impact on a commercial building, but it’s a great start and it’s free.
Investigate interconnection options
Nonprofit organizations also should consider interconnection options. Having a grid-tied solar system means that an organization will need to work with the local utility to apply for permission to feed the electricity that the system produces into the grid. There are two parts of interconnection: 1) making sure that the building’s electrical system is up to code and ready for a solar system; and 2) getting permission from the utility to turn the system on.
A professional should be consulted regarding the existing electrical system. Because the solar modules produce direct-current (DC) power and utilities use alternating current (AC) power, an inverter is used to convert the DC power into AC power. The AC power can then flow to the building’s electrical panel and to the building’s meter. Making sure all these systems will work with the new solar system is important so that plans can be made for any necessary upgrades and additional upfront costs. Starting an interconnection process with the utility early in the project development may help identify any additional requirements or upgrades needed to install a grid-tied system. If this sounds overwhelming or too technical, remember that your local North American Board of Certified Energy Professionals (NABCEP)-certified solar installer can do all of this upfront work for you as well. They interface with the utility on behalf of customers every day and speak their language.
Some questions to ask the local utility include:
• What documentation is required to submit with the interconnection application (e.g., building permits, plans, account statements, etc.)? Your local permitting office will also have requirements for issuing an electrical permit.
• Are any rate classes excluded from participating?
• If the account is on an excluded rate class, when and how should it be changed to a valid rate class prior to applying for interconnection?
• Can my contractor complete the application or any other required paperwork for me?
Research financing options (if applicable)
Solar resources that include information about financing options, as well as state and local incentives or rebates, may be found in the U.S. Department of Energy’s Database of State Incentives for Renewables & Efficiency (DSIRE).