1. Flow during sun hours = 100 m³ ÷ (5.5 h × 3600 s) = 0.00505 m³/s
2. Hydraulic power = 9.81 × 0.00505 × 30 = 1.49 kW
3. Pump shaft power = 1.49 ÷ η_pump 0.60 = 2.48 kW
4. PV capacity = 2.48 ÷ (0.95 × 0.90) × 1.2 = 3.5 kWp
5. Buffer tank = 100 m³/day × 1.5 = 150 m³ (water storage replaces battery — 蓄水=蓄能)
6. No-battery design stores energy as water; optional battery (37 kWh) only needed for night/overcast pumping.
📋 Design notes
Water storage = energy storage: The core of direct PV pumping is to over-pump during sunshine into an elevated/ground tank, so the water itself is the "battery". This eliminates battery CAPEX, replacement and round-trip losses — the key advantage over battery-buffered pumping.
No-battery vs battery: No-battery: 150 m³ tank (~1.5 days) supplies water overnight and through 1–2 cloudy days. Battery option (≈37 kWh) would run the pump at night instead, but costs more and adds maintenance — recommended only when a tank is impractical or land is scarce.
Pricing basis: PV modules, pump inverter and mounting are priced from the catalogue. Submersible pump, buffer tank and piping are quoted per project (POA) — pump price depends strongly on head, casing material and depth.
Daily supply: The system is sized to deliver 100 m³/day at 5.5 peak-sun-hours. On shorter or cloudier days, output falls proportionally — the 1.2× PV safety margin and 1.5× tank buffer absorb typical variability.
Design review: This is a preliminary sizing. Verify borehole yield, static/dynamic water level, total dynamic head (incl. pipe friction) and sand content before selecting the pump.