Embed photovoltaics directly into the running surface of roads and paths

Mechanism

Encase solar cells under a traffic-rated transparent surface (tempered/textured glass or resin) and lay them as the road or path deck itself, so the same square metre carries vehicles and generates electricity. Variants add LED lane markings and resistive heating for snow-melt. The appeal is maximal surface reuse — no separate land, no structures.

Where it fits

This is the most aggressive interpretation of the parent issue: reuse the running surface directly. It targets the enormous area of existing roadway (the US alone has ~4 million miles of road).

Why it fails

Every documented real-world pilot has under-delivered or failed outright, for reasons intrinsic to the concept rather than execution:

• Flat orientation loses ~30–40% versus tilted panels before any shading.
• Shading and soiling from vehicles, dirt, and debris cut output sharply.
• Durability under load — traffic-rated glazing cracks, delaminates, and abrades; drainage and thermal cycling compound it.
• Parasitic loads — embedded LEDs and heating can consume >25% of generated power.
• Cost — road-embedded PV has run 8× (per watt) to 360× (per m² vs asphalt) more expensive than putting the same panels on a roof or beside the road.

Verdict

The land this approach "saves" is the cheapest input in the system, and it sacrifices the tilt, cleanliness, and cheap protection that make PV economic. Any residual niche is light-traffic, low-load surfaces (bike paths, plazas) — and even there, output has lagged nearby rooftops. The attached case studies document the failures in detail.