Hi Sierra,
That is a great question. Solar cells are different colors depending on the treatment they recieve in processing. We see the light that has been reflected off the cell, and it is absorbing what we don't see, (at least that in the visable spectrum). So the darker the cell, the more that cell absorbed light in the visable spectrum. But light from the non-visable spectrum also had energy in it, and we can't see that.
Cell manufacturers coat the cells with different layers to absorb certain wavelengths of light. They are trying to convert the maximum amount of solar energy to electricity. They all have their stratigies, with cost on one side and complexity of process on the other - the more expensive processes yeald the most output.
Some companies make cheaper solar modules and their modules make less energy per area of module. If you use those modules you have to buy more of them to produce the energy you need. Others companies try to pack the most amount of production into the smallest package, at a higher cost. These modules are expensive, but it takes less area to produce energy from them.
Does that help?
Kelly