Solarisation

Solarisation of Minor Lights
The Northern Lighthouse Board have operated gas powered systems for more than 100 years and these were the first automatic lights in Scotland. In general terms these were installed where a low range, e.g. less than 10 miles, was required. A local Attendant ensured that the gas supply was available and illuminated and that the gas mantle was in good condition. The structure or building (not a traditional lighthouse tower but a small brick building or cast iron cylinder) was regularly painted. An annual gas delivery by Northern Lighthouse Board tender was necessary.

Today these structures can be replaced with low maintenance aluminium towers and eco-friendly solar electric power for the electric lights. Such lights have been operated by the Northern Lighthouse Board since 1985 and have been used in buoys since 1993.
There are currently 121 Northern Lighthouse Board solar powered land based sites from the north tip of the Shetland Isles to Chicken Rock at the south end of the Isle of Man in addition to some 151 floating solar systems all around the coastline. The range of light varies between 3 miles and 23 miles. Lights of less than 15 miles normally used tungsten lamps and drum lenses but are now very often LEDs (light emitting diodes) exhibiting the advertised character by using electronically controlled flashers switching the light on and off.
Solarisation of Major Lights
The Northern Lighthouse Board's first automatic long range lights were also powered by acetylene gas and were first installed in the early 1960s. Lens systems mounted on a turntable rotated using the gas pressure from the acetylene gas cylinders, were installed in traditional lighthouse towers. A sun-sensitive gas valve controlled the supply to the gas mantle, allowing economic use of the available gas. Nevertheless, an annual supply trip by Northern Lighthouse Board tender was necessary.

Development of high efficiency metal halide lamps has allowed the replacement of the gas mantle to be achieved using solar-electric systems which charge batteries by generating an electric current directly from sunlight. In the northern latitudes of Scotland and the Isle of Man, the solar panels can make use of the diffused light through the cloud cover and the battery is of a size to accumulate sufficient energy in the summer and autumn months to ensure winter operation. The power consumption for the typically required light range of 18 miles has decreased in the last decade from over 100 watts to 35 watts making use of highly efficient lamp drivers operating directly from the 24 volt battery supply. Supplementary power for monitoring purposes is supplied from small wind powered generators.