Battery-Less Off-Grid Renewable Microgrid: A Review of Storage Alternatives and PV-WT-CSP Integration with Green Hydrogen

Abstract

Renewable energy systems play a critical role in reducing carbon emissions and promoting energy sustainability. Conventional battery storage remains the dominant but problematic solution for intermittency management in off-grid renewable energy systems (RES), imposing high capital costs ($150-400/kWh for lithium-ion), short replacement cycles of 3-15 years, and significant environmental burdens from toxic material disposal barriers that are particularly acute in the remote and resource-limited communities that most need reliable clean energy. This paper presents a systematic review of battery-less off-grid RES, synthesizing evidence across six alternative energy storage and dispatch technologies: supercapacitors, mechanical flywheels, compressed air energy storage (CAES), pumped hydroelectric storage (PHS), hydrogen storage via PEM electrolysis, and molten salt thermal energy storage (TES). The review spans single-source, dual-source, and multi-source configurations, with documented applications in seawater reverse osmosis desalination, agricultural water pumping, rural electrification, and small-scale industrial processes. A comparative performance analysis reveals that no single battery-less technology is universally optimal; rather, hybrid approaches particularly molten salt TES paired with hydrogen storage offer the most robust solution for continuous, dispatchable off-grid power. Building on this synthesis, the paper proposes and characterizes a novel integrated battery-less microgrid combining solar photovoltaic (PV), wind turbine (WT), and concentrated solar power (CSP) with molten salt thermal storage and PEM-based green hydrogen production. The system’s defining innovation is the dual-pathway utilization of stored hydrogen: as a long-duration electricity backup via fuel cells and as a direct fuel for agricultural vehicles and equipment, eliminating diesel dependence in off-grid farming contexts. Key findings indicate that such integrated systems can reduce curtailed renewable energy by up to 79%, eliminate battery replacement costs over a 20-year operational lifespan, and provide multi-day energy autonomy without chemical battery storage. Critical challenges including electrolyzer cost reduction, small-scale CSP adaptation, and energy management system design are identified as priority directions for future research to enable widespread deployment. HOMER Pro-based techno-economic validation is identified as the immediate next step in this research work.