Using Electric Water Heater Tanks as an Energy Storage Solution to Solve the Duck Curve Issue

The electricity production transition leads to the development of low-carbon content renewable energy resources, such as photovoltaic (PV) panels. Due to the later, utilities operators see a significant drop in mid-day net load, raising concerns that the conventional power system will be unable to accommodate the ramp rate and change needed to fully utilize solar energy. Also, this could result in overgeneration and curtailed renewable energy, increasing its cost and reducing its environmental benefit. This paper presents and quantifies a solution that has the potential to help solve this issue and help the development of more PV panels. It consists of using electric water heater tanks to store the excess energy produced by the PV panels by heating the water above the typical setpoint during mid-day hours. Simulations have been run through EnergyPlus (EP) using the average profile of hot water consumption in the US and modified scheduled of water heater to show the feasibility and impact of the methodology. Across California, it has been evaluated that up to 59 GWh of energy could be potentially stored per day during mi-day hours through this technique, reducing by 97% the current need to add expensive energy storage devices, such as batteries, to flatten the duck curve.