Comparison between results of th HELIOS and MIRVAL computer codes applied to central receiver solar-energy collection

The Sandia computer codes HELIOS and MIRVAL were developed to predict the optical performance of reflecting solar concentrators and to model power collection by central-receiver solar-energy power plants. HELIOS is an analytic code, whereas MIRVAL uses Monte Carlo ray-tracing techniques. They have been used both internally and externally in many studies including evaluation of heliostat-receiver design, parameter studies and safety analyses. The objective of this study was to verify that HELIOS and MIRVAL give the same performance predictions. The sample problem for comparison consists of a rectangular target and alt-azimuth heliostats deployed in a north field. The results indicate that HELIOS and MIRVAL closely agree on predictions of field performance and of power density on the target plane.