"James Hart" wrote
| I am sure on this sort of duty cycle solar panels woud work
| or windmills, but the cost....
| We've suddenly got a plague of reactive road warning signs
| popping up all over the county. They are all on long poles
| with a windmill on the top and solar panel just below.

How securely concreted in? ;-)

There are big photovoltaic panels on some railway signalling equipment too.

Owain