Peak Sun Hours — The One Number That Sizes Your Array
Peak sun hours is not how long the sun is up. It is the day’s total solar energy compressed into hours of 1000 W/m² “standard” sun — and it is the divisor that sizes every PV array.
Definition
A location receiving 5.0 kWh/m² in a day has 5.0 peak sun hours, whether the sun was above the horizon for 11 hours or 13.
Typical values
| Location | Annual avg PSH |
|---|---|
| Metro Manila / Luzon | 4.5–5.0 |
| Visayas / Mindanao | 4.8–5.5 |
| Dubai, UAE | 5.5–6.0 |
| Sydney, Australia | 4.2–4.8 |
| London, UK | 2.3–2.8 |
Use PVGIS, NASA POWER, or Meteonorm for a site-specific monthly profile — design to the worst month for off-grid, and the annual average for grid-tied.
Tilt and orientation
Maximum annual yield comes from facing the equator at a tilt near the site latitude. Near the equator (Philippines, 6–19°N), a low tilt of 10–15° is common — enough for self-cleaning in rain while staying close to optimal.
Sizing the array
Performance ratio (0.75–0.82) bundles inverter loss, temperature loss, soiling, wiring, and mismatch. Example: 20 kWh/day ÷ (4.7 × 0.78) = 5.5 kWp.
EngEst Pro’s Solar PV Calculator pulls a PSH value for your selected location and applies it to your load — you get the array size in kWp, panel count, and a full BOM with financial estimate in local currency.
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