1-Wire Solar Radiation Sensor
Earth Measurements page 84
There are four tools for measuring light intensity:
A Pyranometer measures light energy hitting a surfaces during
a given period of time. Useful for solar energy systems. The
is watts per square meter.
A Photometer measures the light intensity our eyes see.
The measurement unit is lux or footcandles.
A PAR (Photosynthetically Active Radiation) measures the
light intensity as it effects the growth of plants.
The measurement unit is micromoles of quanta per square meter per
A Spectrophotometer determines how much light energy is in
each narrow band of wavelengths across the light spectrum.
Circuit and Components
There are several different approximations that can be done. The current in photodiodes is equal to
a constant times the light intensity.
Full summer sun on a clear data is approximately 1000 watts per square meter (75 watts per square foot).
Full summer sun light is approximately 110,000 Lux or a 100 watt lightbulb viewed from
1 meter is approximately 100 Lux.
Full summer sun light is approximately 2000 moles per square meter per second.
Solar Radiation References