Tag Archives: irradiance

Rotating Shadowband Radionometer (RSR)

Rotating Shadowband Radionometer (RSR) are a cheap and precise way to measure the solar energy resource (global, diffuse and direct radiation) with a silicon photodiode radiometer and a shadow band.

This system was developed by Dr. Edward Kern, MIT professor who I personally met few years ago, who founded in 2003 Irradiance, Inc. the company which manufacture the Rotating Shadowband Radionometers (RSR2).

Rotating Shadowband Radionometer (RSR2)

Rotating Shadowband Radionometer (RSR2),Image from Irradiance

The Irradiance RSR2 head unit uses a rotating curved band and a single, fast-response, photodiode sensor to measure global and diffuse sunlight. Direct sunlight is calculated by Irradiance’s computer program onboard the Campbell Scientific data logger. It includes a head unit, motor controller, temperature/relative humidity sensor, data logger, PV/battery power supply, cellular modem for remote data access, and stable, light-weight tripod. Continue reading

Solar irradiance on sunny and cloudy days

The solar radiation that is emitted from the sun in the form of electromagnetic waves, entering the atmosphere is filtered by the gases it contains, mainly by clouds that are floating, which bounce the light to operate as mirrors. When passing a cloud, global radiation decreases dramatically and diffuse radiation increases as a result of the deviation in the direction of the aces of light that causes the cloud.

Figure 1: Solar radiation in a sunny day

Figure 2: Solar radiation in a partly cloudy day