A mess of panels.
TOKYO — Solar panels have sprung up across Japan in the past few years, after the government introduced a “feed-in tariff” in July 2012 that guarantees prices for electricity generated from renewable energy. When these panels reach the end of their working lives in 20-30 years, they will create a mountain of waste.
By 2020, Japan’s Environment Ministry forecasts the country’s solar-panel waste will exceed 10,000 tons.
After that, the pile really starts growing: reaching 100,000 tons in 2031 and topping 300,000 tons in 2033, the 20th anniversary of the feed-in tariff.
Between 2034 and 2040 the amount of waste produced is expected to hover around 700,000-800,000 tons annually.
The projected peak of 810,000 tons is equivalent to 40.5 million panels.
To dispose of that amount in a year would mean getting rid of 110,000 panels per day.
sunshine hours 
That is absolutely nothing compared with the problem of plastics. ABSOLUTELY NOTHING.
Why not?
And how many waste cars will be in 10 years? Think about it.
I’m pretty sure they know how to recycle a car in Japan.
I’m pretty sure they will know how to recycle solar panels in twenty years.
https://cleantechnica.com/2016/06/21/recycling-old-solar-panels-e-waste-today-gold-mines-tomorrow/
In fact, is much more profitable to recycle a solar panel than plastic or wheels.