A smart energy management system that allows homeowners to charge their electric vehicles from rooftop solar panels has been developed by Fraunhofer researchers.
The home energy management system (HEMS) runs on small, embedded computers and collects data from various electricity meters in the house which includes those for the photovoltaic (solar) system, the electric vehicle, the heat pump and general household power.
The system displays the various power flows and informs homeowners about their current power consumption at any time of the day.
The HEMS also forecasts solar intensity over the next day to determine how much solar power is, and will be, available.
The system uses this data and anticipates the household’s power needs to determine how much solar power is available for charging an electric vehicle at any given time.
“Electricity from the PV first goes to the house and power that is not consumed there is stored in the electric vehicle battery. If there is still any electricity left over after that, it is fed into the public electricity grid,” explains Dominik Noeren, a scientist at the Fraunhofer Institute for Solar Energy Systems.
By intelligently predicting the power supply and distributing it appropriately, HEMS ensures that homeowners maximise the effectiveness of their solar panels, minimising the amount of power that is fed back into the national grid, which is the least cost-effective usage.
Widespread adoption of the technology would also prevent electricity surges to the national grid during times of strong solar power generation.
“The large photovoltaic systems on the rooftops of the houses provide more power than the inhabitants consume over the long term,” said Noeren.
“[Consumers] can see how much power is coming from either the public grid or the household solar system and they can see where it is going – to the heat pump, household appliances or the electric vehicle.”
The HEMS system is based on the Fraunhofer openMUC framework, which supports a wide variety of meters and devices. It offers modular expandability for integrating devices such as wireless Bluetooth or WLAN power outlets that can remotely activate and deactivate household appliances.
The researchers believe that in addition to helping homeowners lower their energy costs, the system is a useful tool for realising the ideal of low-CO2 homes and personal mobility.
Earlier this year, electric car manufacturer Tesla Motors unveiled a home battery system designed to store solar energy when rates are cheap for use in expensive peak times.