> and I would like at least some forest to remain forests

You're dramatically overestimating the actual land coverage that would be needed to power the entire world with solar panels (assuming one abstracts away the problem of actually running power lines everywhere). A square 340 miles on a side would do it, from the back-of-the-envelope calculations I've seen.

The forests are not cut down because of solar panels, but because of agriculture. The more land that is covered with solar panels, means less land for agriculture (I like the dual use concept, though).

The spaces here in germany, that are covered with solar panels, would have been adequate agriculture area, but is now ugly and in use. So if you could just use the road as the space, you could save that other land for other use. This is the idea behind it.

> No, because land close to humans is limited

It's not that limited. Think how many roofs there are. Or car parks.

Also HVDC power transmission is a thing now. You don't even need to have your power source close to humans.

"Also HVDC power transmission is a thing now."

It has always been a thing, but it still means losses and expenses to build it. If you could have solar panels in the road, you could charge electric cars directly and efficently. But like I said, unlikely to happen.

I mean yeah but "if we had magical technology that doesn't exist we could use it" isn't a very interesting fact.

Solar panels are a very real technology and solar roads are working.

It is just that they are too expensive to make much sense. With many potential new solar tech that is in the pipeline, that might change.