How to choose the right size storage capacitor?

First  think about what your application is. Do you want a motor to spin for a long time or just a a few turns? If you want it to spin for a long time then you're going to need a capacitor with higher capacitance. If you want a motor to spin for only a quick burst then a smaller capacitor is what you want.

Nothing comes for free, of course, so the bigger the capacitor you have, the longer it will take to charge up and move. So a 2200uF (0.0022 F) capacitor might take only a second to charge but a 1F capacitor could take 8 minutes.

Here's a few sizes commonly used

• Dual SE photopopper -- 3300 uF (0.0033 F)
• Solaroller -- 0.033 - 0.047 F (depends on solar cell size)
• Symet -- 3000 uF (3 x 1000 uF)