Solar Resource Models and Tools
The Renewable Resource Data Center (RReDC) features the following solar resource models and tools.
Bird Clear Sky Model
This algorithm estimates clear sky direct beam, hemispherical diffuse, and total hemispherical solar radiation for horizontal planes.
Bird Simple Spectral Model
This model computes clear sky spectral direct beam, hemispherical diffuse, and hemispherical total irradiances on tilted or horizontal planes.
DISC estimates direct beam irradiance from user-supplied hourly average measured global horizontal data.
PVWatts: A Performance Calculator for Grid-Connected PV Systems
The PVWattsTM calculator estimates the electrical energy produced by grid-connected photovoltaic systems.
Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS)
SMARTS computes clear sky spectral irradiances for a set of user-specified atmospheric conditions.
Solar Position Algorithm (SPA)
SPA calculates the solar position with very low uncertainty based on location, date, and time inputs for the years -2000–6000.
Solar Position and Intensity (SOLPOS)
SOLPOS calculates the solar position and intensity based on location, date, and time inputs for the years 1950–2050.