All of the Following Are Advantages of Using Solar Cells

All of the following are advantages of using solar cells for electricity except

A) they are safe, quite and do not produce any greenhouse gases during operation.
B) they can be made from rigid or flexible materials.
C) they can be easily expanded to form solar cell banks to meet increasing energy demands.
D) they can last as long as a typical nuclear power plant.
E) they need a storage or backup system for electricity.