Solar powered arduino on the back of a playing card

Step 4: Check the output before creating an epoxy tomb

Check the output of your freshly minted panel at your two copper tape outputs -- in noonday sun on a sunny day in, say, Hong Kong, you should read an open voltage of around 3.5VDC - 5VDC (depending on how many solettes you connected in series) and a closed current of, well, whatever the closed current of a single solette is.  For solettes of the area I am using in this project, the closed current is around 175mA.  This is wayyy more than you'll need to power an arduino, even for some heavy duty tasks.  

We programmed an arduino powered off of a CFL without any problem -- and this would be cake in real sunlight.  So, you can do loads with this amount of juice.

Add a supercap or rechargeable batteries if nighttime operation of your project is necessary.