Peer-to-peer (P2P) exchange of renewable energy is an attractive option to engage and empower citizens to actively participate in the energy transition. Whereas previous research has provided techno-economic models and technological solutions to enable P2P energy trading, little is yet known about citizen preferences for solar power trading. Importantly, the impacts of community members’ trading decisions across scales such as individual electricity bills, community autarky, and grid stability remain unknown. Here, we assess actual P2P trading strategies based on an experimental study with German homeowners and simulate how retrieved decision-making strategies impact the performance of P2P communities across the three scales. Our findings suggest that community autarky is higher in P2P communities than in self-consumption communities, even if self-consumption communities search to maximize autarky (an autarky paradox). We show that actual prosumer decision-making may lead to benefits at the individual (reduced energy bills), community (higher community autarky), and grid level (reduced stress).