Abstract
In order to produce electricity in a sustainable way, solar technologies have been identified a productive solution. In addition, decentralized electricity production constitutes a way to scale rapidly the solar-based electricity. Consequently, peer-to-peer solar energy trading schemes are under development. However, the optimal ratio of prosumers (entities that both produce and consume) as well as the drivers influencing this number at a municipality level are still unexplored. Therefore, in this paper we run a simulation on cities in Switzerland to measure the optimal number of prosumers to involve in peer-to-peer energy trading as well as the gap compared to the current situation. Switzerland announced in 2023 a significant change in its regulation, allowing peer-topeer electricity markets at municipality level in 2025. We find the majority of optimal prosumer ratio lays between 18 % and 37 % and that the majority of municipalities would need to increase their prosumer ratio by 15 %-20 %. The interplay between production capabilities, consumption demands and non-residential buildings share proved to be very defining drivers: 1) The impact of non-residential buildings constitutes the most critical insight of the simulation 2) The more diverse the community's production and consumption profiles are, the more suitable for peer-to-peer solar energy trading markets the communities are. We conclude with measures for Switzerland to close the gap and reach its objective: include non-residential buildings in solar electricity production and start installing smart meters on a large scale.