The phrase "year backlog" means that there is a large amount of tasks or work that have accumulated over the course of a year and still need to be completed. Full definition
Even with a $ 408 million financial hit due to tax reform, the company remains in good shape as it transitions to Series 6 production and raised its 2018 guidance as it plans to bring back some Series 4 capacity to meet its 2 + year backlog of demand. (pv-magazine-usa.com)
Which is well before the patent is even granted (2 + year backlog at the USPTO), clinical trials, FDA approval, production, etc etc.. (getrichslowly.org)
With upwards of 8 - year backlogs investors are paying close attention to on - time delivery numbers and, by this metric, one of the two takes the win. (fool.com)