Like many products, the solar power industry needs all kinds of engineers. Yes, there are chemical processes involved, but also structures to hold the solar cells, materials engineers, manufacturing engineers, etc. to produce the product. At this point it seems that solar cell research is quite mature and most of the effort is in making the cells cheaper to produce. Therefore, not a lot of jobs in the chemical process area.
Choose the field of engineering that you like and will do well in is the best way to have a good career in engineering.