Must-have elements for your stage-1 proposal in HORIZON-CL5-2026-04-Two-Stage-D3-02 for next-generation renewable energy
23rd January 2026 at 11:22 am
The pathway of the European Union (EU) to climate neutrality by 2050 depends on more than incremental improvements of existing renewable energy technologies. The two-stage Research and Innovation Action (RIA) HORIZON-CL5-2026-04-Two-Stage-D3-02 is designed to support breakthrough, high-risk and high-return concepts that can reshape the energy system and strengthen Europe’s long-term innovation base.
With a stage-1 deadline of 31 March 2026 and a total budget of €23.50 million for six projects, this call places strong emphasis on early strategic clarity and challenges applicants to convincingly articulate ambition, feasibility and societal relevance within a short proposal. Stage 1 is not a sketch. It is a decisive filter where evaluators assess whether a concept is credible and relevant to justify further development. Below, we outline what not to miss when positioning your concept for success at stage 1.
Understand the strategic logic and stage-1 expectations
This topic targets technologies that go clearly beyond the current commercial state of the art. Proposals must demonstrate potential to deliver game-changing renewable energy solutions that surpass today’s commercial solutions, while strengthening Europe’s industrial independence, long-term innovation capacity and transition to a net-zero economy by 2050.
The scope is deliberately broad but not open-ended. While areas such as hybrid renewable systems, solar-driven chemical processes, advanced storage concepts or integrated heating and cooling solutions are mentioned, several other domains are off limits: Research on hydrogen electrolysers, fuel cells, and batteries as well as basic material research are explicitly excluded, as these topics are covered in other calls.
Although concise, the stage-1 proposal must already present a coherent concept supported by robust research logic with awareness of technical, environmental and societal risks. Evaluators expect clarity on what is new, why it matters, what risks exist and how these risks will be addressed. Concepts that remain abstract or speculative, without a clear feasibility pathway at technology readiness level (TRL) 4–5, are unlikely to pass this first filter.
Must-have elements to be competitive at stage 1
1. A clearly framed high-risk, high-return concept
The proposal must articulate why the technology is genuinely transformative rather than incremental. Risk should be acknowledged explicitly, with a clear explanation of where uncertainty lies and what potential breakthrough could be achieved if the risk is successfully addressed.
2. Credible technological feasibility at TRL 4–5
Even at stage 1, the proposal must demonstrate that the concept can realistically reach or consolidate TRL 4–5. This expectation requires a clear description of the technological approach, the core components of the system and a research methodology capable of establishing feasibility.
3. Economic viability embedded from the outset
Economic performance is a core evaluation dimension. Proposals should already compare the expected performance of the new technology with current commercial renewable energy solutions. This method includes an early discussion of cost drivers, efficiency gains, scalability, long-term competitiveness and energy security without requiring a full business plan.
4. Environmental performance, biodiversity and resource efficiency
Minimal environmental impact is an explicit expected outcome of the call. Stage-1 proposals should identify potential impacts on biodiversity, pollution, land use and resource consumption and explain how these will be mitigated through design choices and research activities.
5. Social acceptance, integration of social sciences and humanities (SSH) and policy relevance
Effective SSH involvement is mandatory. Proposals must show how SSH expertise will contribute to understanding citizen trust, social acceptance, local involvement and just transition aspects. Policy analysis should address adaptive and context-sensitive policy approaches that support future deployment.
6. Contribution to the European innovation ecosystem
Finally, proposals should demonstrate how the concept strengthens Europe’s innovation base, which includes openness to cross-sectoral technology transfer, awareness of relevant European research infrastructures such as RISEnergy, as well as alignment with broader EU energy and industrial policy objectives.
Have you decided to apply and are you looking for proposal preparation support?
At accelopment, we support consortia developing ambitious renewable energy technologies that combine technical excellence with economic realism, environmental responsibility and societal relevance. Our experience spans high-risk innovation projects such as PEPPERONI and SOLARX, which advance next-generation solar technologies and innovative energy conversion concepts, as well as HEAT-INSYDE and H-DisNet, that focus on integrated heating, cooling and energy system solutions. Through ADEL and CHEOPS, we have further supported projects addressing advanced energy technologies, performance validation and long-term reliability. Together, these projects reflect our strong involvement in renewable energy innovation, system-level integration and sustainability-driven research under Horizon Europe.
From shaping clear stage-1 concepts to preparing evaluator-ready stage-2 proposals, we help research teams position their ideas strategically, align them with EU policy priorities and maximise their chances of success in competitive two-stage calls.
Dr. Johannes Ripperger
Research & Innovation Manager
Andreia Cruz
Research & Innovation Project Manager