National Renewable Energy Laboratory - System ADVISORY Model - Is the software we use to design your system and calculate savings.
S.A.M. calculates the cost and performance of renewable energy projects using computer models developed at NREL, Sandia National Laboratories, the University of Wisconsin, and other organizations.
It takes every detail into account. For example: The slope and facing direction of your roof, local weather conditions, actual equipment models used in the project all the way down to inflation and system degradation.