The 1N914 diode is something every solar project needs. It blocks the flow of power in one direction, which is how you keep power from flowing back into the solar cell at night.
This diode is great, but should only be used in solar projects where the solar cell is at or below about 200mA. The diode only allows up to 200mA, so the extra energy will be wasted if you have a massive cell.
Contains 10 Diodes in this pack.