Recently, I posted about using a solar panel as a method for charging a battery that powers the Arduino.  Although using a solar cell as a power source is the most obvious use, it is not the only use!

I found a post over at little-scale that shows how to use a solar cell with an Arduino as a photo sensor.  The code looks very similar to reading a pot, or other such device on an analog input.  Although, there a few caveats to doing this noted by little-scale:  The solar panel used in this example was rated at 2V and 25mA.
• Do not use a solar panel rated in excess of 5V. Doing so may damage the Arduino
• If data values appear incorrect, try scaling the byte ‘data’ in the Arduino sketch as it is captured. The analog inputs read data at 10 bit. However, a single, serially-printed value can only hold 8 bits of information.
• The data range with this particular solar panel is 0 < 6 using power-efficient, indoor lighting at night.

The next question after HOW could be WHY? There a many different applications that spring to my mind, from practical to abstract. I am also curious if you could still use a panel as a sensor and power source, by having one trace going to the analog input, and another going to the power source.

I have also decided to include a few examples from practical to abstract, to get your thoughts flowing on this subject.  The first example is a “practical” one from youtube user, ringsofdeath.  The second is a more “abstract” one from youtube user, 5imian.  I hope you enjoy the videos and they get the juices flowing!

• Read the blog post at Little-Scale on “solar sensing”

http://little-scale.blogspot.com/2008/03/connecting-solar-panel-to-arduino.html

• View a “practical” example of solar sensing on YouTube

http://www.youtube.com/watch?v=oThoa_zHTkk&NR=1

• View an “abstract” example of solar sensing on YouTube

http://www.youtube.com/watch?v=L5iPpLnZeyU

The first and perhaps easiest way that jumps to mind, is using a small solar panel to recharge a 9 volt battery used to power the Arduino.

I came across a wonderful Instructable by p2man that illustrates the basics on how to setup a solar panel charging circuit.

I can see this being a great way to power self contained devices like weather sensors or other such devices.  This way they can just sit and collect data, or do their task and we don’t need to remember to replace the battery. Thus a solar powered Arduino project can be left to do it’s own thing… SET IT, and FORGET IT!

• Read p2man’s Instructable on the Self Sufficient Arduino

http://www.instructables.com/id/Self-Sufficient-Arduino-Board/