In this project, we decided to create an HTTP Server and Client been run by an MKR1000. A solar Server!. In order to accomplish this, we have to measure the power consumption of the microcontroller.Just as an experimentation upload the Blink Sketch available in the Arduino examples to test how much power is drawn by an Arduino without a wifi connection. The result of this measure is amazing, showing us 5 volts at 20mA, which is less consumption than a regular DC motor running properly. The effectiveness that these commercial microcontrollers amazed my eyes.
Once we upload and sketch connecting to WIFI the consumption will vary between 110 - 130mA without significant changes.
Now, we know what is the solar panel we will need. Our choice was a 6V, 2W solar panel which means 0.33 A, if we think Watts = Amps * Volts. According to the documentation MKR1000 has a power regulator up to 6V built in the Vin pin so we are able to connect directly to Vin and GND without a power regulator.
The solar panel exposed to indirect sun light is able to boot the Arduino, but the power supply is so variable, booting the micro controller multiple times really quickly without any connection to internet. Connecting the same solar panel to a DC motor, the amperage read by the multi-meter in series is 8 mA but it is not even moving which logically is less than the needed min 10 mA to power the MKR1000. Our set up is just powered up by direct sun light getting 4.5 Volts and 120mA. We designed a simple box to glue on the glass, this location receives sun light around 11.00am.
We decided to monitor the values and running time of our little box using internet of things IoT (cayenne at https://cayenne.mydevices.com) meanwhile it is running a simple HTTP Server and Client sketch. Next day the results are that the micro controller runs the server from 11am to 12.30pm intermittently.
Graphing the data we got:
The behavior is consistent on the same range of hours (from 11 to 1 pm). The only days the server was running for more that one hour were Thursday and Sunday., which means less clouds generating shadows.