An April 2018 article in Solar Power World covers the state of solar recycling:

"Solar panel disposal and recycling isn’t a huge issue right now in 2018 because there isn’t a big enough volume to cause concern. Solar panels are warrantied to perform more than 25 years, and once the warranty expires, panels will still produce energy, albeit not at their advertised peak. Solar installations in the United States didn’t really take off until 2010. Any influx of panels needing replaced today happens after freak weather events or other accidents.
But where are those damaged panels going now? With no dedicated national program or requirement to safely dispose of solar panels, some unfortunately find their way to landfills. If the system owner is green-minded and has the money, panels may get shipped to a recycling facility. Other industry players are warehousing damaged or old panels until a practical recycling program is established...
There’s nothing yet mandated at a national level, but there are a few states trying to get the required recycling ball moving. In July 2017, Washington became the first state to pass a solar stewardship bill (ESSB 5939), requiring manufacturers selling solar products into the state to have end-of-life recycling programs for their own products. Manufacturers that do not provide a recycling program or outline will not be able to sell solar modules into the state after Jan. 1, 2021. Regional takeback locations will be set up to accept solar panels at no cost to the system owner, and the state may charge manufacturers for the program. Final plans are still being decided."

Read more on ESSB 5939 and the Washington Dept. of Ecology's implementation.