The use of renewable energy systems in remote refugee camps can provide sustainable access to electricity for communal services (CSs), thereby supporting the services offered to refugees and ensuring clean energy access. Proper sizing of these renewable energy systems helps organizations create electrical systems that benefit the camp community while considering cost optimization. This paper demonstrates the techno-economic sizing of a renewable energy-based electrical system to serve CSs in Kobe Refugee Camp in Ethiopia, where Alianza Shire has been implementing a project since 2021. The paper presents the methodology used to size the electrical system, considering various techno-economic constraints, and shares the lessons learned, including challenges such as limited access to energy consumption data for the CSs in the camp. The work also demonstrates approaches to optimally size the electrical system through three design cases, considering different inputs linked to the capital expenditure (CAPEX) of the project and technical limitations. The results show that the proposed solutions are sensitive to capital costs. Thus, introducing a small capacity shortage significantly reduces the project's capital cost, but it only has a minor impact on energy access during limited durations annually. The presented methodology and outcomes in this paper can be extrapolated by energy practitioners and policymakers to inform the power system design for refugee camps. Moreover, this work contributes to the advancement of Sustainable Development Goal 7 (Affordable and Clean Energy), promoting inclusive and sustainable energy solutions for displaced populations.