This seminar will examine the potential for the mild concentration (Cg < 3) of sunlight via non-tracking distributed arrays to provide electricity and heat in California.  Specifically examining the market demand for natural gas heating and electrical energy demands in the residential sector, I will present results of thermodynamic modeling using a Rankine cycle and X-CPC collectors to heat working fluids (R123, ethanol, water) for co-generation of electricity and heat.  By addressing distributed electrical generation as well as domestic hot water, space heating, cooking, and thermal storage needs, this solar technology promises electrical generation at a lower cost than photovoltaics, with significant natural-gas displacement to boot.  Further development of low-temperature generator-expanders and high-temperature collectors suitable for residential/commercial use is ongoing at UC Berkeley, and UC Merced.