The new roadmap of the European Union (EU), the European Green Deal, aims at tackling climate adaptation, energy, biodiversity, and pollution challenges. To contribute to such aim, the latest EU Renewable Energy Directive defines for the first time renewable energy communities. Among them, Photovoltaic-Green roof Energy Communities (PGECs) emerge as a potential option in urban areas. This paper investigates whether and under which conditions PGECs are capable to meet the objectives of the European Green Deal in an economically convenient manner. Since some conditions are context-specific, this research is showcased using a case study (Luxembourg). First, European legislation was reviewed to determine the suitable legal model for PGECs. Second, a systematic literature review helped identifying lifecycle costs and benefits of photovoltaic-green roofs and their value ranges. Third, a model for probabilistic social and private cost-benefit analyses was developed and tailored to Luxembourg. Lastly, Scenario Discovery was used to identify the ranges of input values leading to desirable net present values. Results show that PGECs can contribute to achieving multiple objectives of the European Green Deal in an economically convenient manner. From the societal perspective, PGECs are found to be economically convenient for any cost, benefit, and discount rate in the case study. From the private perspective, PGECs remain convenient in 62% of the scenarios, with green roofs’ installation cost and electricity generation benefit playing pivotal roles. This paper presents a rare combination of probabilistic cost-benefit analyses and scenario discovery, It supports policymakers designing incentive schemes for PGECs, and can be replicated in other countries.

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In the face of environmental challenges of unprecedented scale and urgency, the European Commission enacted in 2019 a new comprehensive growth strategy with the aim of reaching net zero greenhouse gas emissions in 2050. Named as the European Green Deal, this strategy includes energy, biodiversity, pollution, and climate adaptation targets, and envisages that all EU actions and policies will contribute to its objectives. However, to date, specific actions addressing biodiversity, climate adaptation, and health issues from within the energy sector are still missing or lagging behind. This research proposes a new form of Renewable Energy Community (REC), which combines the use of solar photovoltaic panels with green, namely vegetated, roofs to address multiple Green Deal’s objectives. First, this form of REC was grounded in the current European legislation so to ensure its eligibility for the support schemes that Member States are currently required to devise. Next, the costs and benefits of this REC were determined with value transfer for a case study in Esch-sur-Alzette (Luxembourg) and a probabilistic cost-benefit analysis (CBA) was conducted. By applying Scenario Discovery, the CBA was simulated under different combinations of input parameters and rather than only providing multiple net present values (NPVs), the ranges of input values resulting in desirable NPVs were determined. As a result, the conditions under which the photovoltaic-green roof energy community becomes economically convenient were determined, providing guidance to national policymakers designing RECs’ incentive schemes at present.