An Emissions Arbitrage Algorithm to Improve the Environmental Performance of Domestic PV-Battery Systems

Domestic PV-battery systems are rarely operated in a way which specifically maximizes environmental benefit. Consequently the studies that seriously examine such systems often find that the greenhouse gas and pollutant emissions savings of rooftop PV, though still positive, are lessened by adding a domestic battery. This study shows thatby simulating a PV-battery system with a range of sizes that this need not be inevitable. A novel algorithm was designed specifically to perform ‘emissions arbitrage’: to charge the battery when the grid emissions intensity is low and to discharge when it is high. It was found that the CO2 saved relative to the same system with PV only can more than pay back the CO2 debt of manufacturing the battery. This is true as long as the UK moves away from the present-day situation where natural gas-fired generators are nearly always the marginal generator. This work underlines the importance of both the operating strategy and the interactions between the system and the entire grid, in order to maximize the environmental benefit achievable with domestic PV-battery systems.