Three shades of green: Perspectives on at-work charging of electric vehicles using photovoltaic carports

Electric vehicles (EVs) are widely heralded as the silver bullet for greening personal transport. However their eventual impact in South Africa, a developing country with a low-capacity carbon-heavy grid, is questionable. This paper examines the potential impact of electrification of the vehicle fleet in South Africa, and explores the concept that large employers (or car park owners) could take advantage of the country's abundant sunshine and provide photovoltaic (PV) solar carports for employees (or parking clients) to charge their vehicles while at work. We assess the extent to which this would reduce the potential burden on the national grid, and also consider the economic perspectives of the vehicle owners and the service providers. Our assessment employs a mobility model and a battery model for the vehicles, and solar simulation with measured data for the PV generation. We show that without the provision of additional solar generation, charging four million vehicles from the grid would exceed the grid's capacity. Further, the carbon footprint of an electric vehicle charged from the grid would be greater than that of a petrol-fuelled vehicle, negating any potential benefits of electrification. However, we demonstrate that photovoltaic charging at work renders electric vehicles more carbon-friendly than petrol equivalents, and has substantial financial benefits for the vehicle owner, the service provider, and the grid.