Power Trading within an Energy Community: Applying a fair unequal sharing rule of photovoltaic energy

Energy communities (ECs) with photovoltaic (PV) installations can reduce their collective electricity costs by sharing self-generated power among members. This paper presents a comprehensive framework to address key challenges such as rooftop sharing, heterogeneous ownership structures, and electricity trading protocols. We propose the Weighted Constrained Equal Awards (WCEA) mechanismÑa proportional and fair allocation rule that distributes the benefits of internal energy trade. Unlike existing approaches, the WCEA accommodates diverse ownership arrangements and varying consumption patterns. This “fair-unequal” protocol promotes both the formation and long-term stability of ECs and is robust to strategic manipulation. We evaluate the WCEA using high-frequency metering data in a Monte Carlo simulation. Results indicate that a sufficiently large PV system can reduce median energy costs by up to 65%. Enabling peer-to-peer energy trading yields additional savings: approximately 2.5% when consumption patterns are similar, and up to 11% when they are highly heterogeneous. Moreover, shared PV generation reduces reliance on grid electricity, offering ancillary benefits to the distribution network. However, large-scale PV installations may also create stress due to temporal mismatches between generation and consumption. These findings suggest that policy incentives should prioritize installations that currently satisfy less than half of the prosumers’ energy demand. • Energy communities (EC) with shared photovoltaic (PV) panels reduce electricity costs. • Weighted Constrained Equal Awards rule allocates benefits fairly and transparently. • The WCEA promotes open, stable, flexible and manipulation-resistant EC formation. • Empirically, a large PV can cut energy costs by 65%, plus up to 10% via P2P trading. • Policy should favor PV setups meeting under 50% of current building energy demand.