Solar PV's are essentially made of the same materials used in computer chips and most modern electronic semiconductors. That material would be highly refined silicon, with trace amounts of elements having one more valence electron (phosphorous) or one less, (boron).

There are trace amounts of cadmium in some PV's. That cadmium is unlikely to be released in normal usage, or even in a fire. 1KwHr generated from coal releases 360 times as much cadmium into the air as is encapsulated in in the amount of PV's needed to generate 1 KwHr.

Silicon tetrachloride is used in processing, and a company in China dumped a bunch of the stuff on a field rendering it unfit for food production, and releasing hydrochloric acid which caused major eye irritation in the area. That silicon tetrachloride can and must be recycled.

Smelting sand into semiconductor grade silicon is quite energy intensive. Estimates run from 3 - 12 months for a panel to generate enough energy to repay that energy debt. Trucking waste, if not recycled on-site, adds to the carbon footprint, if carbon based transport is used. There is no reason solar powered plants cannot manufacture solar panels, and i believe there are some that already do.

Coal and gas emit 100's of times as much pollution as solar watt for watt, and most of it is dumped right into the air or water (see MIT study that there are 200,000 early deaths per year from fossil air pollution in the U.S. annually). Nuclear waste? Fuggeddaboutit!

Recycling of solar panels is kind of a non issue, as they take decades to lose enough output to actually need recycling. Many from the 1970's are still producing near full output. It's a crystal!

For solar to approach 100% "Greenness" these issues need to be addressed. But to stick with our highly polluting energy infrastructure while waiting for every last crumb of solar pollution to be addressed results in way more pollution.