1. Solar Cells Solar cells are made of two types of silicon Normal silicon has no free electrons N-type silicon has been doped with phosphorus to give it extra electrons P-type silicon has been doped with boron to give it extra “holes” for electrons to be in

2. Semi-conductors and doping

4. N-typeP-type e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e-

5. N-typeP-type e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- Photons of light energy

6. As more electrons on in the n-type silicon absorb photons of energy more can make the jump and move through the p-type silicon These moving electron cause a current to flow in a circuit connected as shown