Availability of Direct Normal Radiation for Solar Furnace Processing: A Case Study

Predicting the availability of direct normal solar radiation is important for scheduling tests and estimating economics of solar furnaces. This paper looks at historical hourly average direct normal data to predict seasonal trends and report historical availability. Data collected at the Solar Radiation Research Laboratory (SRRL), located within 100 meters of the National Renewable EnergyLaboratory's (NREL's) High-Flux Solar Furnace (HFSF), are analyzed to determine availability of the furnace for testing and processing samples. The design of NREL's solar furnace allows considerable flexibility in processing samples under solar radiation levels of 100-1100 W/m2. Flux levels of 1-2000 W/cm2 can be delivered and controlled. Different processes pose different requirements for bothincident flux and time. The historical data for this site show how often the hourly average direct normal solar radiation is above a certain threshold over the period 1981-1992. Results also show how many tests could have been completed (or samples processed) using five-minute data from 1992. Effects of Mt. Pinatubo are also assessed.