The scarcity of land resources has become a bottleneck restricting the development of photovoltaic (PV) energy, and it is imperative to expand PV layout into the ocean. However, existing studies lack a refined site selection framework for large-scale sea areas. This study takes the Northwest Pacific coastal waters as the research area and constructs a three-stage evaluation framework for the suitability of offshore PV site selection, which includes “resource potential–spatial exclusion–multi-criteria assessment”. The results show that the theoretical power generation potential is generally “higher in the south and lower in the north”, with some deviations in local areas due to differences in temperature and wind speed. Only 4.3% of the sea area is feasible for development. The high-suitability areas are concentrated in the southeast coast of Vietnam and the northwest side of Taiwan Island. The South China Sea has superior development potential, while the Bohai Sea and the Yellow Sea are relatively less suitable. This study generates the first offshore PV site selection map covering the research area, providing a scientific basis for the formulation of differentiated development strategies for regional offshore PV. It has important practical value for promoting the sustainable development of blue energy.

The manuscript adopts the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol to conduct a comprehensive analysis of the methodologies and critical factors influencing the site selection for offshore photovoltaic (PV) projects. The study innovatively proposes a three-stage site selection method model of “exclusion–optimization–correction” and a four-dimensional factor framework, which encompasses “technology, economy, environment, and policy.” The study underscores the pivotal roles of solar radiation, water depth, and grid connection conditions in site selection, while also highlighting the “veto” impact of military exclusion zones and ecological redlines. Additionally, it identifies the challenges associated with data acquisition and standardization in site selection, advocates for the establishment of standardized assessment procedures, and offers theoretical underpinnings and decision-making guidance for the rational site selection of offshore PV projects.

Islands are vital geographical units with significant economic, ecological, and sovereign value. However, their development often faces challenges such as fragile ecosystems, limited resources, and inadequate infrastructure. In response, China proposed the “Harmonious and Beautiful Islands” initiative in 2022, aiming to achieve a balance between production, living, and ecological functions on islands. This study evaluates the implementation of this initiative in Zhejiang Province, a key maritime region with numerous islands. Using a comprehensive indicator system comprising 7 first-level and 36 s-level indicators, we assessed 13 well-developed islands. Results show disparities in overall scores, which correlate with the economic development levels of their administering cities. Among the seven dimensions, Cultural Advancement and Development of Unique Local Industries performed best, while Ecological Protection and Restoration and Green and Low-Carbon Development lagged behind. The study highlights the importance of tailored policies, ecological restoration, and integrated planning in promoting sustainable island development. China’s experience offers valuable insights for global small island developing states (SIDS) seeking sustainable pathways.