Seasonal reliability of a PV-biogas-battery system for rural Morocco: A simulation-based study of digestate valorization and circular bioeconomy benefits

Rural agricultural households in semi-arid Morocco face persistent energy insecurity due to seasonal solar variability and dependence on subsidised butane. This simulation-based study evaluates a standalone photovoltaic–biogas–battery system (2.5 kW PV, 250 Ah battery, 2600 W biogas generator) for a 10-person household in Demnate, Morocco, using 100 kg/day of mixed organic feedstock. Five representative scenarios were simulated using PVGIS-SARAH3 hourly climate profiles, with biogas availability modelled through temperature-sensitive Arrhenius kinetics, hierarchical energy management, and solar thermal pre-heating. Under nominal assumptions, no unmet electrical load was simulated in the five single-day scenarios, including the zero-irradiance case, which used an 85% initial battery charge, an extended biogas-dispatch window, and temporary load curtailment. Biogas contribution increased from 26% in summer to 40% in winter, and solar pre-heating reduced auxiliary heating demand by 43%. Without thermal management, simulated winter loss of power supply probability (LPSP) rose to 21.8%. Annual digestate nitrogen recovery was estimated at 125 kg/year of ammoniacal nitrogen, valued at 3415 MAD/year using literature-derived coefficients. The electricity LCOE was 2.81 MAD/kWh (sensitivity range 1.87–4.12), against a 6.50 MAD/kWh butane benchmark. The estimated net annual system benefit was 19,340 MAD/year, with a 2.3-year simple payback including digestate valorization. Stress tests produced LPSP values of 17.2% after two consecutive zero-irradiance days and 37.4% under prolonged cloud. These results suggest that hybrid systems may support rural energy services and agricultural co-benefits under these assumptions. Experimental validation, continuous annual simulation, site-specific digestate characterisation, and agronomic field trials are needed before practical deployment.