Increasing the Utilization Ratio of Photovoltaic Energy by Network Hybridization

The traditional architecture of electric power networks is limiting the usage of massive decentralized photovoltaic energy to the immediate neighborhood of the production units. When generation largely exceeds local consumption, solar energy production needs to be curtailed in order to avoid equipment overloading and power quality problems. The necessary investment in grid infrastructure to overcome this limitation represents a serious adoption barrier for renewable energy. In this work we explore a solution path based on the concept of hybrid energy grids investigated by the European OrPHEuS project, where different energy carrier networks benefit from mutual energy transfer. Applying the hybridization principle, we consider the approach to feed surplus energy into the domestic hot water systems of residential houses and thus reduce energy (e.g. fossil fuel) consumption of the primary heating system. We examine various strategies for controlling this energy exchange process, ranging from purely local decision schemata to fully centralized control algorithms. In an extensive experimental study, based on accurate simulations of the electricity grid and the thermodynamics of domestic hot water systems, we confirm the feasibility of our approach and determine the best choices of devices and control strategies. In our simulations we were able to reduce the yearly usage of heating fuel by 65% utilizing surplus energy from local solar panels.