The appearance of solar powered road signs happened without a great deal of fuss and publicity but these are one of the few transport developments based on renewable energy to become an overnight success. Once you become aware of them, you start to see them everywhere; typical solar powered signs come on only when you drive towards them (they often have speed detectors built in) and they may have a small wind turbine on top, as well as their solar panels.
Advantages of Solar Powered Road Signs
The obvious advantage is that such road signs do not use fossil fuel energy and so are carbon neutral after they have been in operation long enough to offset their production costs and impact. Solar powered signs work all the year round, helped by efficient capacitors and back up wind turbines. Their other major plus point is that they need very little installation – no electrical cables need to be nearby – they can be taken to their site of use and simply attached to the ground or to a post for stability.
Signs can be placed where they are needed, and warning signs can be positioned during road works and then taken away again to use somewhere else without any disruption to the footpaths nearby. The speed sensors built into most solar powered road signs are very sensitive, and make sure that the solar power is only used when traffic is on the road. When the road is quiet, the sign is not illuminated and uses no power.
Solar Powered Traffic Lights
Solar powered road signs, such as signs reminding drivers of a speed limit, have been so successful, the technology has been extended and is now used in mobile traffic lights. These have long been a feature of sections of temporary road works but the solar powered versions make it unnecessary for electric cables to be laid, or for a noisy generator to be used to power them.
Solar Powered Street Lighting
This is still in the development stage in the UK but new types of street lights called Green Columns could soon by lining some streets in the UK. These will look like normal street lights but the solar panel and wind turbine will be positioned above the light, providing renewable energy for street lighting. These are particularly useful for dark areas that have no cabling to allow connection to the electricity grid and that have been previously unsafe for walking at night.
Companies who make solar powered street lights also supply them for business use for car parks, recreation areas, footpaths, parks and bus and train stations. The lights are fitted with a light sensor, so that they just illuminate the surrounding area when conditions are dark enough, and can also be fitted with an infra-red detector – so they light up when someone walks along a path, for example. A back-up battery is added so that the light still works during the darkest days of winter when there is no wind.
Future Solar Developments
One other solar application that has not taken off was the solar powered cat’s-eye for the road surface. These were installed during trials in particularly dangerous stretches of road, showing red or amber LED light to warn oncoming traffic of congestion or problems. Worries about the impact of their flashing on people with epilepsy have prevented them being developed further but new research is underway in which cat’s-eyes start to show a blue light if the surface temperature of the road falls below 3 degrees – warning drivers of the possibility of ice on the road.