How to size a portable power station for an off-grid clinic

Off-grid clinic procurement is a sizing problem before it is a price problem. Under-sized kits leave the cold-chain to fail; over-sized kits eat scarce humanitarian budget. This guide walks through the inventory-load method we use with health-ministry and INGO procurement teams to size a NURION Sirius + Nuria + Watiqa kit correctly the first time.

1. Inventory the loads

Walk the dispensary and write down every device that *cannot* be off during a grid cut. A typical primary-care dispensary inventory:

• 1× paediatric incubator (warm), 100 W continuous, 12 hours/day
• 1× vaccine fridge (WHO PQS class), 35 W cooling / 2 W idle, 24 hours/day
• 1× vital-signs monitor, 25 W intermittent, 8 hours/day
• 2× LED ceiling lights, 12 W each, 12 hours/day
• 1× nebuliser, 60 W intermittent, 1 hour/day

2. Convert to daily Wh

Multiply each device by hours × duty cycle:

| Device | Power | Duty | Daily Wh |

|---|---|---|---|

| Incubator | 100 W | 12 h × 1.0 | 1,200 |

| Vaccine fridge | 35 W cooling × 30 % + 2 W idle × 70 % | 24 h | 286 |

| Vital signs monitor | 25 W | 8 h × 0.4 | 80 |

| Ceiling lights × 2 | 24 W | 12 h | 288 |

| Nebuliser | 60 W | 1 h × 0.5 | 30 |

| **Total** | | | **1,884 Wh/day** |

3. Add safety margin

Add 25 % for inverter losses (AC loads), self-discharge, and a buffer for surprise loads. 1,884 × 1.25 ≈ **2,355 Wh/day** required.

4. Pick the Sirius capacity

Sirius capacities are 1.0 / 2.0 / 3.0 kWh. The closest match is **Sirius 2K** (2,000 Wh), which gives ~85 % daily replenishment from solar with an over-night reserve for the cold-chain. For grid-stable sites, Sirius 2K is enough. For sites with extended grid blackouts (>24 h common), step up to **Sirius 3K** to add a full day of cold-chain autonomy.

5. Pair the solar input

Solar yield in the Middle East averages 5.5 peak-sun-hours/day (PSH). To replenish 2,355 Wh/day:

> 2,355 Wh ÷ 5.5 PSH ÷ 0.85 system efficiency ≈ **504 W** of panels.

Round up to **2× Nuria 200 W = 400 W**, plus an existing rooftop module (~100 W) — or **3× Nuria 200 W = 600 W** for full standalone capability.

6. Move the cold-chain to DC

Replace the AC vaccine fridge with a **Watiqa Fridge** (12 V DC, Danfoss-class compressor): 35 W cooling drops to 35 W cooling — but you save the 12–18 % inverter conversion loss. Daily fridge Wh drops from 286 to ~243.

Final kit

| SKU | Qty | Note |

|---|---|---|

| NUR-SIR-2K | 1 | 2 kWh LiFePO4 |

| NUR-NUR-200 | 2 | 400 W folding solar |

| NUR-WAT-FRIDGE | 1 | 40 L vaccine cold-chain |

| NUR-SUH-YARD | 2 | Outdoor security lighting |

This kit handles the daily 1,884 Wh load with 2,355 Wh capacity headroom; recharges in 4–5 hours of clear sun; and runs the vaccine cold-chain for 72 hours of full grid blackout.

For project-specific sizing, NURION provides free pre-deployment sizing review for ministry-of-health and accredited NGO buyers — submit a Project Inquiry with your device inventory.