  With the costs of renewable energy technologies declining, new forms of urban
energy systems are emerging that can be established in a cost-effective way.
The SolarEV City concept has been proposed that uses rooftop Photovoltaics (PV)
to its maximum extent, combined with Electric Vehicle (EV) with bi-directional
charging for energy storage. Urban environments consist of various areas, such
as residential and commercial districts, with different energy consumption
patterns, building structures, and car parks. The cost effectiveness and
decarbonization potentials of PV + EV and PV (+ battery) systems vary across
these different urban environments and change over time as cost structures
gradually shift. To evaluate these characteristics, we performed
techno-economic analyses of PV, battery, and EV technologies for a residential
area in Shinchi, Fukushima and the central commercial district of Kyoto, Japan
between 2020 and 2040. We found that PV + EV and PV only systems in 2020 are
already cost competitive relative to existing energy systems (grid electricity
and gasoline car). In particular, the PV + EV system rapidly increases its
economic advantage over time, particularly in the residential district which
has larger PV capacity and EV battery storage relative to the size of energy
demand. Electricity exchanges between neighbors (e.g., peer-to-peer or
microgrid) further enhanced the economic value (net present value) and
decarbonization potential of PV + EV systems up to 23 percent and 7 percent in
2030, respectively. These outcomes have important strategic implications for
urban decarbonization over the coming decades.
