Generally speaking, you want panels to:

• Have minimal shading (especially by e.g. poles for overhead traction)

• Not get contaminated by dripping oil/grease/brake dust.

• Not complicate access (either by being in the way or by being damaged and live) for repairs or rescue efforts.

• Not be subject to vibration or impact.

• Be located densely and near connections to the electrical grid, so that the cabling per panel is minimal.

This breaks just about every one of those.

Go put panels on every house/mall/supermarket and then panel roofs over every carpark and railway station first, then we’ll talk.