This paper details modeling assumptions and simulation results for an unglazed collector system supplying domestic hot water, space heating, and space cooling loads. Collectors are modeled using unglazed collector test results. Variation of savings with collector area, storage volume, heat exchanger size, and wind for the Albuquerque, NM climate are shown. Over the storage-to-collector ratio range of 40-640 l/m(2) collector, annual savings varies only +/-15%. Cooling is sensitive to heat exchanger size, and heating is sensitive to wind velocity. At a collector area of 23 m(2) the unglazed system meets about 56% of the annual total energy demand, saving 25.9 $/m(2) yr for an all-electric home. For the 23 m(2) area, savings for a cold/damp (Madison) and a hot/humid (Miami) climate are 64% and 56%, respectively, of the savings in Albuquerque. (C) 2004 Elsevier Ltd. All rights reserved.