Light Logger

measuring sunlight availability

July 19, 2018

Working with sensors is always fun. This time, I am assembling a light sensing device to measure sunlight availability. The device records light with a TSL2561 sensor, and time with a DS3231. The sensors are controlled by an Adafruit Adalogger which logs the recorded data onto an SD card. A tiny 500mAh Li-ion battery powers everything.

Wiring up the sensors is easy. Both the TSL2561 and the DS3231 connect with the micro-controller via I2C. The code is on my Github page. Below is an image of the sensor, a video showing how to use it, and some sample data.

Arduino codes

Sensor image

So, here is the device, compact, power efficient, and does a good job so far.

How-to video

I had to send these sensors to Dublin for deployment in the area where we have high-resolution LiDAR data. So I prepared this video to explain to my peers in Dublin how to run the sensors.

Sample data

Here are some sample datasets we collected (in blue) plotted together with a simulation dataset (in red). I should have mentioned earlier that the sensors were put together to evaluate the solar potential simulation we did. The measured data shows that the sunlight increased gradually from sunrise, peaked at noon, and reduced towards sunset. The sudden jumps happened at the time direct sunlight illuminated the sensors.