Reducing PV Performance Uncertainty by Accurately Quantifying the PV Resource

Reducing uncertainty in the prediction and/or verification of photovoltaic (PV) plant output can directly increase the expected return on investment for each party in a contract, likely leading to more favorable terms for the contract, including a possible reduction in interest rates. Note that a reduction of 1% in the interest rate is estimated to reduce the levelized cost of energy by approximately 0.5 cents/kWh (Branker, Pathak, and Pearce 2011). This project developed a capability to provide spectrally resolved solar information from the National Solar Radiation Data Base (NSRDB), effectively providing 20 years of half-hourly data for all of the United States at a 4-km by 4-km spatial resolution. These data are now available freely to users directly through a geographic information system-based Web interface (https://nsrdb.nrel.gov) as well as through an application programming interface (Sengupta et al. 2018; Xie and Sengupta 2018; Xie, Sengupta, and Dooraghi 2018; Xie, Sengupta, and Dudhia 2016). Users of these data can conduct more accurate prefeasibility studies and assess multiple PV technologies. It is expected that widely used models such as PVSyst, the National Renewable Energy Laboratory's System Advisor Model (SAM) (Blair et al. 2014), and PlantPredict, designed by First Solar, will develop the capabilities to use these spectral data.