Download the Solar Site Evaluation Quick Checklist.

There are two recommended levels of solar site evaluation:

1. A project solar screening, which is a high-level, preliminary analysis used to determine a site’s likely viability, and
2. A project solar feasibility study, which is a more rigorous engineering and economic analysis to define specific system design considerations for use in requests for proposals and/or scope of work development.

For projects that propose to use alternative financing (i.e., a third party ownership model), a project solar screening is sufficient to proceed. For agency funded projects, a solar feasibility study is recommended. The points that both types of solar evaluations should cover are defined in the sections that follow.

 

Project Solar Screening
A project solar screening should encompass the following.

STRUCTURAL OR MECHANICAL CONSIDERATIONS
■ Roof condition, manufacturer’s warranty, and age of roof (if considering a rooftop system)
■ Shading analysis (identification of obstructions that might shade the array location)
■ Available square footage for a solar system
■ Preliminary estimate of the system’s size
■ Structural issues and—if the system is to be mounted on a building—height considerations
■ Historic building issues (if the system will be on a building that could be a historic property or is located in a historic district).

ECONOMIC CONSIDERATIONS
■ Cost of energy (electricity and fuels) at a site, plus any details of rate schedules that could favor or penalize solar
■ Economic analysis of project (e.g., simple payback, internal rate of return [IRR], net present value [NPV], life cycle cost [LCC], projected savings)
■ Estimated annual energy production
■ Hot water or space heating demand
■ Incentives (federal, state, local, utility, RECs) and their time sensitivities.

 

Project Solar Feasibility Study
A project solar feasibility study should encompass the following in addition to the project solar screening components.

STRUCTURAL OR MECHANICAL CONSIDERATIONS
■ Capacity of the local industry to supply and maintain such systems
■ Utility interconnection issues (if planning an electric project, it’s important to know whether the utility has special hardware or contractual requirements)
■ Electrical room or mechanical room issues (e.g., space for equipment, alternate location, capacity limits, access between system and equipment room).

ECONOMIC CONSIDERATIONS
■ Recommended system size
■ Site load requirements (these should be checked against system sizing)
■ Analysis of 15-minute load data for peak demand
■ Estimated monthly peak production
■ Annual operations and maintenance (tasks, annual costs)
■ Magnitude and timing of the electric and heating loads at a site
■ Size, condition, and efficiency of existing heating systems.

See the DOE report Procuring Solar Energy: A Guide for Federal Facility Managers (Sept 2010) for more information.

 

Analysis Tools

Solar Technology Analysis Models and Tools | NREL

This page contains a list of computer software that can assist in the design of solar energy systems and/or passive solar heating and cooling techniques for buildings.

 

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