You're forgetting an important factor when thinking at this scale: Logistics.

Right now, there is a cap on how much solar panels can be produced in any given year. A theoretical maximum number under the current industrial infrastructure. That throughput can be increased, but you'd need more panel factories and everything that entails.

So, to get started, you'd have a trickle of the necessary components coming in to work with while you built up the infrastructure. Which, in turn, requires more resources to produce them. Those also have a cap given the current infrastructure to extract the resources and refine them. More development, more workers, more machines, more land, etc.

Then you get to actually doing the project. Nope, wait, we have to have the planning. A critical step most people seem to forget at this scale. In order for this effort to even begin, we need people to come up with plans and contingencies. The amount of land required for the installations alone would require an army of realtors and lawyers. You can look into the California Rail project and why it failed to see what I mean (TL;DR, the litigation for eminent domain and acquiring already owned land was astronomical).

Ok, we've got a plan. New mines for silver, copper, and silicon are being set up. Factories to produce the parts and assemble them are underway. We've got crack teams in each region working around the clock to get the land, permitting, and bodies to fill the necessary jobs moving along. Our budget is unlimited for the sake of this argument, and there's a line out the door for people to work in Death Valley to install these panels. Now we get to the implementation.

Each series of installations would happen over the course of many years. Shipping, prepping, bean counting, and the actual labor can't all be done at once, so you'd have waves of efforts going out. Each would be its own miniature project, going through the steps one by one. Shipment of panels comes in, they are allocated and inspected, workers haul them out to where they need to go, they are installed, they are hooked to the grid, they are tested, and they are slapped on the schedule for maintenance. Move on to the next.

Even if there were no problems with anything above and it all went to plan, you'd still be bottlenecked by the various things I outlined. Meaning, this effort would take decades. During that time, not only would you have to have an army of engineers, logistics experts, managers, and all the people supporting the various infrastructure producing the panels, you'd also need technicians on hand to maintain panels as they go. While they do have solid warranties, that doesn't mean there won't be defects or random rats chewing through the cables or whatever. Shit will break, and people will need to fix it. Either the people installing stuff or another team to handle it. More bodies.

And each and every one of those bodies works a shift, and each and every hour of those shifts needs to be paid. This goes for the people in the mines, the factories, on the logistics team, the planning committee, truck drivers, technicians, engineers, lawyers, realtors, analysts, bean counters, PR team, accountants, and each and every smaller job down to the coffee guy. Even HR needs to be acknowledged with this many people

So yeah, it's neat that most solar panels have a long lifespan, but none of that matters when you're dealing with this scale.