Off-grid solar-battery microgrid for rural health facilities — design, hourly simulation & cost analysis in Python.
# Solar-Battery Microgrid for a Rural Health Center in Rwanda
An independent engineering project that designs and simulates a standalone solar-battery
microgrid capable of reliably powering a rural health center in Rwanda — and proves it
costs roughly **half as much as a diesel generator** over 25 years.
**Author:** Hussein NSANZIMFURA · Electrical Power Engineer · Kigali, Rwanda
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## Problem
Many rural health centers in Rwanda lack a reliable grid connection and depend on costly,
unreliable diesel generators. Yet they run critical loads — vaccine refrigerators, lab
equipment, delivery-room lighting — that cannot lose power. This project asks: can a
solar-battery system supply such a facility reliably and affordably?
## Approach
The design followed five stages:
1. **Load assessment** — built an hourly demand profile for a typical health center.
2. **Solar resource** — pulled 19 years (2005–2023) of irradiation data from PVGIS for a
site near Nyagatare; used the worst month (4.06 peak sun hours) as the sizing basis.
3. **Sizing** — sized the PV array, battery and inverter with standard off-grid formulas.
4. **Simulation** — an hourly energy-balance model in Python tracking battery state of charge.
5. **Economics** — levelized cost of energy vs. a diesel generator over 25 years.
## Final Design
| Component | Specification |
|----------------|--------------------------|
| Design load | 20 kWh/day |
| Solar array | 7 kWp (13 × 550 W) |
| Battery | 40 kWh lithium (LiFePO₄) |
| Inverter | 6 kW hybrid |
| System voltage | 48 V DC |
## Key Results
- **Reliability:** 0 kWh unmet load — supplies the facility every hour, even in the worst
solar month. Minimum battery state of charge: 12.3 kWh.
- **Cost:** solar LCOE **$0.364/kWh** vs. diesel **$0.727/kWh**.
- **Savings:** ≈ **$70,600** over 25 years compared with diesel.
*24-hour system performance: solar generation, load, and …