Solar-Powered Sensors

Sensor designers and developers continue to make their mark as significant innovators in the automation and control sector. Over the past few years we’ve seen several examples of cutting edge wireless sensors and battery-less sensors powered by external energy sources such as vibration and heat. Because of their low power needs, sensors are often the ideal device with which to showcase the potential for alternative energy sources in the industrial sector.

The newest entry into wireless, battery-less sensor arena is the Unitronic Solar CO Sensor Module (USCSM), a wireless, solar-powered sensor module whose function is to warn when carbon monoxide concentrations are elevated. The most obvious use for such a sensor is in building monitoring applications, but it can also be used in industrial applications as part of a facility or machine design.

USCSM features an electrochemical carbon monoxide sensor, developed by Figaro, in the shape of a AA battery which meets DIN EN 50 291 (electrical apparatus for the detection of carbon monoxide) and Association of German Engineers VDI 2053 guidelines. Also onboard is an STM 300 programmable, bidirectional wireless sensor module for use at 315 MHz or 868 MHz from EnOcean.

No external voltage supply is used on the sensor. All energy needed to power the sensor is provided via solar cells integrated on the USCSM module.

The carbon monoxide detection range of the USCSM is from 20 ppm to 1000 ppm. Measurements are conducted every 20 seconds in normal conditions. The wireless module transmits current values of CO concentrations and of the supply voltage once an hour. An operating time of up to 60 hours in darkness is typically achieved with these measurement and transmission cycles.

If CO concentrations rise, the number of measurement and transmission cycles automatically increases. When this occurs, the current value of the supply voltage enables a continuous analysis of the anticipated remaining operating time. Visual or audible warnings ensure that operators are notified in time to reach safety and correct the problem.

The USCSM module measures 55 mm x 24 mm x 22 mm. Customer-specific adaptations are also available.