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Effects of ambient temperature and drive cycle on electric vehicle charging using photovoltaic systems

Gürer, Erim
Global warming and climate change problem can be solved by only decreasing greenhouse gases (GHGs). About 26% of the global GHG emissions are emitted by the transportation sector. Switching from fossil fuel burning vehicles to electric vehicles is one of the most promising solutions. However, 68% of the electricity is generated by using fossil fuels in the world and if a switch to electric vehicles happens without transforming the electricity generation sector, transportation emissions might even increase. Therefore, EVs are only as clean as their energy source. Implementing renewable energy into transportation sector is a crucial step that must be taken to reduce transportation emissions. Wind energy resources have larger spatial and temporal variations compared to solar energy. In addition, solar energy is much easier to estimate and imply. PV plants can be installed in a decentralized way. Thus, every parking lot can be covered with PV. In this study, a general model is developed to estimate the energy generation from PV-covered parking lot systems and energy demand for electric cars. After the model is developed, case studies are performed using temperature and drive cycle information for Istanbul, Los Angeles and New York City. These locations are compared in terms of PV-EV feasibility considering several aspects. On the energy demand side, the effects of ambient temperature and driving style are considered to have a more accurate model. The results show that PV system can cover the annual demand for all case studies. The annual energy demand of 10 cars in Istanbul case study is about 300 MWh while the energy generation from the modeled 22.5 kW PV system is about 306 MWh. In the comparison of two cities, Los Angeles which represents mild ambient conditions is more favorable than New York City which represents the ambient conditions which include cold winters and hot summers. The results reveal that the ambient and driving conditions can increase the energy demand by 50%. As a result, PV-EV systems decreases the stress on the grid due to EV charging. Scheduled charging can increase the benefit even more.