SAM — System Advisor Model

SAM computes two things together: how much energy a system will produce, and what it is worth. On the technical side it simulates hour by hour across a full year — photovoltaic, concentrating solar, wind, geothermal, biomass and battery storage — from a weather file and equipment characteristics. On the financial side it runs a full cash-flow model: capital cost, financing, depreciation and tariffs, returning LCOE and payback period.

That makes it the right tool for sizing a rooftop solar system on an industrial building, judging whether storage pays, or comparing configurations. Developed by NREL and distributed free, with source code.

Note: the financing and tariff model is built for the US market. The physics is right everywhere; tariff and financing assumptions must be entered for local conditions.