Cost and environmental metrics for this project and the whole idea of solar roads simply makes no sense. One has to wonder what's at play here. Why is something like this funded when it makes no sense?

From the article:

- It's 30% less efficient than roof-mounted systems
- Each set of panels is encased in concrete and glass
- These systems cost 3x more to install

My notes on the above:

The 30% drop in efficiency is a dream. It's worst than that. Fill the road with bikes dirt, trash, grease, oil and surface abrasions (or cars in the case of a future solar road) to get real numbers. This simply isn't sensible. It's akin to building a solar array and planting huge trees over it.

The fact that the panels require thick concrete and thick truck-proof glass makes this terribly expensive. There's an environmental and energy cost here.

In other words, environmentally, it takes a lot more pollution (waste materials and the overall industrial process) to make each of these panels than it does to make panels that don't have to support a truck. Imagine these modules being made in China to be shipped via tanker truck to Europe or the US while burning millions of metric tonne's of nasty polluting bunker fuel.

Ditto for energy. It takes energy to make, transport and install heavy glass and concrete. I wonder if these panels will ever make back the energy required to manufacture and install them. No data on this, of course, just educated conjecture on my part. I do think I'm right.

On the matter of cost, it should be obvious that such an installation is massively more expensive than roof-mounted panels. I would go as far as suggesting this might be massively more expensive even in the case of roof mounted panels when a structure has to be built to support them.

Maintenance costs would be very high, requiring constant washing, cleaning, removal of leaves and dirt and polishing just to maintain the substandard energy production level offered.

What would the cost and performance metrics be if you took the same length bike road, built a structure over the entire length and mounted the panels atop this structure? My guess is that cost would be significantly lower. Maintainability would be massively cheaper and easier. And energy production efficiency would gain perhaps an order of magnitude when compared to a road full of bicycles, dirt, leaves, etc.

Such quick analysis --didn't even have to open a spreadsheet-- makes me believe projects like these have to be politically driven at some level. I can't see any economic or technical angle whatsoever under which something like this makes sense even at a small scale. And I don't think that scale makes it better.

I wonder if someone familiar with what led to the approval of such a project might be able to shed some light with further details.

EDIT: Spelling. Added a bit about maintenance.

EDIT #2: To address the "if we covered every rooftop we would only produce 25% of the energy the country needs."

What a fantastic problem to have that would be!

Look, at that point you build steel structures atop all the main train tracks and mount solar arrays kilometers long all over the country.

Not enough? Build similar structures atop roads where it makes sense and put solar arrays there.

Not enough? Can you add more wind power.

Not enough? Can you add wave/tidal power generation

Not enough? Can you add nuclear.

Not enough? Can you make a push for more efficient power utilization? BTW, this is probably the best thing the world could do.

Not enough? Well, if the goal is to be 100% solar --which might not be sensible-- you are going to need to use all available surface area as efficiently as possible. Destroying your roads to then install solar roads is unlikely to produce the desired results.