Peak Sun Hours

Definition

Peak sun hours (PSH) are equivalent hours of 1,000 W/m² irradiance. A site with 5 PSH delivers about the same energy as five hours at full STC sun, even if the sun is up for 12 clock hours. Daily harvest is roughly array watts × PSH × a derate (wiring, temperature, soiling, angle — often about 0.75). Winter PSH can be less than half of summer PSH at mid latitudes.

Calculators that use this

• solar panels

  Solar Array Sizer

  Estimate how many solar panels you need from daily watt-hours, panel watts and peak sun hours, including a realistic derate.

• solar panels

  Off-Grid Cabin Daily Solar Need

  Add up fridge, lights, laptop, water pump and other cabin loads to get a daily watt-hour budget for solar sizing.

• solar panels

  Solar Tilt Angle & Azimuth Estimator

  Estimate annual, summer and winter solar panel tilt from latitude, plus true-south or true-north azimuth.