Just when is end of life for a modern system? SolarWorld predicts that 40 years is reasonable for its panels, and Enphase has warranties lasting from 15 to 25 years. In its report for 2014(1) SolarWorld says "Owing to the long service life of solar modules, we do not yet have any significant volumes of returned products to report." And indeed we are only at year five of a long life. In the absence of severe damage such as physical breakage due to a falling tree, massive projectile or very severe hail the built in shatter resistance is likely to keep the panels working for a long time yet.
Eventually the time will come to do some recycling, and the technology already exists. A solar system consists of a number of components: panels and inverters are the delicate parts that are mounted on aluminum racks which in turn are supported on galvanized steel poles mounted in concrete bases. From the top down, we can see the panels being treated as "sharps" in the recycle process, and the inverters join the E-waste process; both of these are handled conveniently by local authorities in Ontario. The remaining components such as the aluminum, steel wiring can be reclaimed by normal established processes. Perhaps the most expensive part would be the removal of the concrete bases, which in some cases will involve a backhoe equipped with a hydraulic hammer drill, and the truck to haul the pieces.
In comparison with the benefit of the installation over its lifetime, the cost of disposal should be quite small. The real cost of this part of the expense side will only be known in about 20 years time when a large number of older panels will need to be processed. At the moment, in the last analysis, SolarWorld is saying that it will accept its old panels for recycling(2).