The single most important decision in this process was the choosing of the solar cells. As was mentioned earlier in the introduction, two major manufactured materials exist for solar cells. The first is silicon. Silicon was the material of the first solar cells and nowadays is mostly used in terrestrial settings due to its low production cost and low efficiency. Terrestrial applications generally value cost over surface area consumed so silicon is a great fit. These cells generally range from 12%18% efficient and come in two crystal types, mono crystalline and polycrystalline