This study investigates sustainable alternatives to diesel generators for data centre backup power, focusing on renewable diesel (HVO), Hydrogen energy storage (HES), batteries (Lithium-ion and Sodium Sulfur) and Compressed Air Energy Storage (CAES). As environmental scrutiny of data centres grows, the need for cleaner energy sources intensifies. Our research assesses various storage technologies' energy performance metrics, environmental impacts, and economic feasibility. HVO is a seamless substitute for conventional diesel, compatible with existing infrastructure and less carbon-intensive. CAES offers lower life cycle emissions and operational costs but is geographically dependent. While currently more costly, batteries could achieve better economics with increased operational hours. However, extending the backup duration increases their capital and operating costs significantly, which is less advantageous than other technologies, where only fuel costs increase with longer backup times. For existing data centres transitioning to sustainable energy, HVO is optimal; for new facilities, CAES is ideal if geography allows, with HES as a robust alternative. This analysis offers a pathway for data centres to adopt sustainable, cost-effective energy storage solutions and reduce carbon footprints through on-site renewables or green energy procurement.@en

The integration of photovoltaic (PV) technology in urban environments poses new challenges for the design of PV modules. In particular, the poor shading tolerance of conventional PV modules strongly limits the energy performance of urban PV systems. In this work, we analyze how interdigitated back-contact solar cells with low-breakdown voltages can help improve the shading tolerance of PV modules. Through detailed simulations, we show that the breakdown voltage can be tuned without significantly degrading the efficiency of the solar cell. Simulation results indicate that, under partial shading conditions, cells with a 0.3-V breakdown voltage could boost by 20% the annual yield of conventional crystalline silicon PV modules with three bypass diodes. These findings are supported by a four-month-long monitoring campaign of PV modules with different breakdown characteristics, which shows a specific yield gain of about 4% in PV modules with six bypass diodes.

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In this manuscript, we discuss the relevance of the reverse characteristics of solar cells in the energy yield of partially shaded photovoltaic modules. We characterize the reverse IV curves of commercially available cells and we simulate the energy yield of photovoltaic modules using an experimentally validated simulation framework. Results suggest that cells with low breakdown voltages can boost the energy yield up to 74% in modules that are heavily shaded. Also, yield gains larger than 1% can be achieved for modules that are partially shaded only 7% of the time.@en