Is the manufacturing process of photovoltaic panels bad for the environment?
Photocells are semiconductors, just like computer chips. In fact, computer chips have to be tested in the dark because photoelectric currents will skew the results.
Semiconductor manufacturing does indeed require the use of some EXTREMELY toxic chemicals, some of which are actually chemical warfare weapons. However the final chip is not particularly toxic because only an extremely small amount of these materials actually get incorporated into them, and it is a very strong chemical bond. The main source of pollution would be manufacturing waste and things like lead based solder used to connect the chips into a solar array.