While solar cells might be almost pure silicon, the panels themselves use a lot more materials to work. For example, 2% of all global copper production was just for panels 2018. The frames and the cells both use aluminum (the actual most abundant material overall). Silver, the most expensive component, has been pushed from about 400mg per panel in 2007 to about 100mg per panel today.[0]
Each solar panel contains about 14mg of lead which means around 4.4k tons were used in the production of solar panels in 2018.[1] This is much smaller than, say batteries (which solar panels drive a huge demand for), but is still significant considering lead has been found to leak into the environment from solar panels even from regular rainfall.[2]
In 2017, a study found that as much as 62% of the cadmium from cadmium telluride models were leached out at room temperature depending mostly on acidity of the solutions.[3]
"Even only one day of leaching of two module pieces in 1 day of acid rain and neutral solution is sufficient to exceed the World Health Organization (WHO) drinking water limit: for Cd the threshold limit is 3 µg=L.33) Even under alkaline conditions (pH 11), it takes only three days to exceed this limit. After nearly one year, the Cd concentration cCd in acidic solutions is almost 20000 µg=L (62%)" [4]
[0] https://www.freeingenergy.com/do-we-have-enough-materials-to...
[1] https://www.freeingenergy.com/are-solar-panels-really-full-o...
[2] https://www.zmescience.com/science/solar-panels-lead-plants-...
[3] https://iopscience.iop.org/article/10.7567/JJAP.56.08MD02/me...
[4] https://sci-hub.se/https://iopscience.iop.org/article/10.756...