This paper presents an improved generic demand-side model that captures the aggregated effect of smart buildings and a large population of prosumers. The model is formulated as a bilevel program. The upper level is cast as a unit commitment problem to emulate the market outcome. In contrast, the lower level maximizes the aggregate self-consumption of prosumers. The coupling between the two levels is done through prosumer demand instead of the electricity price. The formulations are validated and compared on the PJM 5-bus system.