Case Study of Photovoltaic Energy Surplus Absorption by Charging LithiumIon Batteries Considering Chargexe2x80x93Discharge Energy Efficiency In Autumn 2018, reductive control of photovoltaic surplus energy was performed in Kyushu, Japan. This was a lost opportunity to utilize renewable energy, which could have been otherwise stored in rechargeable batteries. In this study, we simulated the absorption of the photovoltaic energy surplus by charging battery systems of a working electric vehicle considering the energy efficiency of lithiumion battery systems to reduce the operation cost. This study clarified the quantitative effects of a realtime energy efficiency diagnosis of lithiumion battery systems. From the simulation results, we discovered that the improvements of the chargexe2x80x93discharge energy loss and the economic gain of the photovoltaic energy surplus absorption depended on the inputxe2x80x93output power of the bidirectional vehicletogrid charger and the amount of surplus energy. When the inputxe2x80x93output power is sufficiently high and the ratio of surplus energy to total capacity of the battery systems is sufficiently low, the improvement in surplus energy absorption profit is reasonable. The realtime degradation diagnosis of the battery systems and selection considering chargexe2x80x93discharge energy efficiency is necessary to improve the profit from surplus energy absorption.

Comparison of Charging Strategies of Electric Vehicles Using Local Power Production to Minimize Carbon Emissions The German WINNER research project aims at controlling and optimizing local power production, distribution, and consumption in residential areas. Beside residents, who consume electrical energy uncontrollable, there are electric vehicles of a car sharing provider as well. Their charging process can be monitored and controlled. Furthermore, we have a midsize photovoltaic (PV) power plant on the roof of the residential building. Within this local area, we measure energy consumptions and productions. This paper covers subsequent investigations on the possibility of using different charging strategies of electric vehicles from the view of the grid side. Thus, we have to measure energy consumption and production, calculate the surplus and store this excessive energy in the vehicle accumulator. We aim to be neutral against the local energy grid or at least not unhelpful, i. e., we have to avoid power withdrawal if possible. In this paper, we abstract from real use case with electric vehicles. We are using a simple battery model and make some assumptions on the energy consumption and PV production referring to our measurements. Afterwards, a recurrent approach is used to schedule charging and discharging processes along the day. We consider various charging aims over time, i. e., we vary the charging states and times, at which the aimed battery charging state should be reached. Finally, we use our system to answer the question, if our approach to lower the grid load was worth it. For low PV power days and cloudy days, we found usable strategies. Referring to PV peak days we had to do more intensive investigations.