Optimized control and aggregation of existing electric water heaters to enable solar PV grid integration

Abstract

Load shifting for existing electric resistance water heaters (EWHs) presents a potential solution to utility challenges caused by the temporal mismatch between solar generation and electricity consumption. A case study in the Florida Power & Light (FPL) territory for both an individual and a fleet of EWHs evaluates this potential. Two optimization problems are solved using mixed-integer linear programming to maximize solar self-consumption and minimize electricity cost for an individual EWH. Compared to default operation, the solar maximization strategy results in nearly twice as much heating electricity from solar (80% vs. 42%) and 14% increased electricity cost based on FPL rates. An energy balance approach shows the aggregate impact of all FPL EWHs on days of peak and minimal load, June 25th and December 3rd. Publicized goals of increased solar capacity by 2030 will cause changes to the FPL net load, total load minus solar generation. The four million EWHs in the territory can stabilize the net load in 2030 as shifting their load causes a 24% decrease in the standard deviation of the predicted load on both dates. These results encourage widespread adoption of retrofit devices that control EWHs based on solar generation profiles and water consumption schedules.

Disclosure statement

No potential conflict of interest was reported by the author(s).