COMPARATIVE ANALYSIS OF MONOBLOC AND MULTI-SUBSYSTEM CONFIGURATIONS FOR PHOTOVOLTAIC WATER PUMPING IN RURAL DRC

Rural water supply in the Democratic Republic of the Congo (DRC) faces significant challenges due to unreliable electricity access. Photovoltaic water pumping systems offer a sustainable solution, but the optimal system architecture—monobloc versus distributed subsystems remains underexplored. This study presents a comparative techno-economic analysis of two configurations for the village of INSTHWEM Mukongo, Kwilu Province, DRC.
The methodology uses field data from 2025 surveys: population of 5,636 (5,566 village residents + 50 hospital beds + 20 healthcare personnel), well characteristics (static level: 30 m, drawdown: 15 m), and solar irradiation (4.7 kWh/m²/day worst month). Two configurations were designed: (A) a monobloc system serving the entire community, and (B) two independent subsystems (village and health center).
The monobloc system requires 9.90 kWc PV, one Grundfos SP 95-3 pump, one CUE 5 inverter, and a 285 m³ tank, with an investment of 70,400 USD and LCOW of 0.083 USD/m³. The two-subsystem configuration requires 10.45 kWc PV (18 modules for village + 1 for health center), two pumps (SP 95-3 and SP 5-8), two inverters (CUE 5 and CUE 1), and two tanks (270 m³ + 14 m³), with an investment of 71,220 USD and LCOW of 0.086 USD/m³.
The monobloc system is 1.2% cheaper in investment and 3.6% cheaper in LCOW. However, the two-subsystem configuration offers superior redundancy (99% service availability vs. 95%), easier maintenance with smaller standard pumps, and greater flexibility for future extensions. Given the remote location and critical importance of water access, the two-subsystem configuration is recommended despite its marginal cost premium.