A solar cell or photovoltaic cell is a device that converts light directly into electricity by the photovoltaic effect. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified. Assemblies of cells are used to make solar panels, solar modules, or photovoltaic arrays.
How does it work??
Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction. The complementary positive charges that are also created (like bubbles) are called holes and flow in the direction opposite of the electrons in a silicon solar panel.
An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
(from wikipedia http://en.wikipedia.org/wiki/Solar_cell)

1. Three parallel solar cells (0.6v each)
creates 1.7v under the desk light.
not enough for BEAM
2. Three parallel solar cells (from Richard)
creates 4.6v under the desk light.
not enough for BEAM
3. flexible solar cells (from Richard)
creates 3v under the desk light.
enough for BEAM
4. solar cells (from overhead bot)
creates 3v under the desk light.
enough for BEAM

5. solar cells (from Conrad)
creates 5.4v under the desk light.
enough for BEAM
6. solar cells (from Conrad)
creates 4.5v under the desk light.
enough for BEAM