True - but if it takes the size of the capital of Morocco to replace half a nuclear power plant, imagine the size of the installations needed to truely power the world with solar energy?
Those are easy numbers to figure, and there's enough empty desert space within Morocco's own borders for all of those installations (assuming you accept their claim over Western Sahara).
Rooftop solar generally uses ~0 new space, and there is quite some reason to believe that prices will continue to drop so that people in sunny regions will install it simply to save money.
It probably isn't the solution to industrial power demand, the local mill here uses more power than the rest of the county, but so what?
As someone who lives in a country (Brazil) which uses lots of hydro, I have a related question...
How much space does it take, compared to a hydro plant of equivalent power? Hydro is also relatively clean, and is also known for taking massive amounts of space.
Hydro is the most environmentally destructive source of power. It ruins more natural habitat than strip mining coal, clearcutting forests, solar PV in virgin land, or any other kind of generation. And the river bottoms and canyons it destroys are among the most biodiverse habitats in the world before their destruction.
In 2013 the plant generated a record 98.6 TWh,
supplying approximately 75% of the electricity
consumed by Paraguay and 17% of that consumed
by Brazil.
I'm sure that most of the citizens of Paraguay and Brazil will gladly accept this inexpensive hydro power, even at the loss of a few flooded canyons.
It's nice to sit in ivory towers and criticize. In the real world, many many people's lives are made much easier and more productive by harnessing this inexpensive hydro power.
You want to solve some real problems in Brazil, figure out how to stop the destruction of the Amazon rain forest. That, there, is a world scale tragedy. Not so the beautiful Itaipu Dam, which I've toured, and which helps so many Brazilians.
True, but you'd be surprised. Morocco has more than two dozen hydro stations, 460MW of pumped storage and there's still some unused capacity for future hydro projects. Hydro obviously isn't the future of electricity for Morocco, indeed there aren't enough rivers, but it's playing a substantial role today as part of the renewable energy mix, e.g. numbers from a few years ago show hydro generated twice as much electricity as all solar/wind.
Take the recent solar project, Noor I, that's launching within a month. Its production is about 370GWH per year, hydro currently does something close to 1900 GWH.
This is where the idea of highway and surface streets being solar panels becomes interesting. This isn't science-fiction either, there are a few pilot deployments already such as:
You're not going to use glass panels in your roads. You're far more likely to use printed spools of flexible cells and cover them with a translucent, pourable protective layer. Some form of epoxy, or a concrete impregnated with optical fibers, perhaps? The efficiency per unit area will be horribly low, but when multiplied by the area of the whole road, you still end up with a lot of power.
You will lose some area to potholes. That's just another reason not to use the expensive, glass-covered cells.