An important feature of the Satel-Light server is to deliver information using clock time (the time used in a country, or part of a country). This way, you can study the performance of a solar energy system for the hours during which it is being used (i.e. working hours in the case of daylighting applications).
Clock time is usually expressed relatively to the Greenwich Meridian Time (GMT) used in the United Kingdom (GMT+3 means three hours more than GMT). The earth is divided in 24 time zones, each having a width of 15° longitude and centered on a reference longitude: 0° for GMT, 15°E for GMT+1, 30°E for GMT+2 and so on. The GMT+1 time zone extends from a longitude of 7.5°E to 22.5°E. The clock time used in a country does not always correspond to its time zone (Spain uses GMT+1 while it is located in the GMT zone). The clock time used over sea and ocean waters may be the one used in the country within the boundaries of each nation sovereignty. However, these boundaries are sometimes unresolved. In Satel-Light, about 20 kms away from the coast, sea and ocean waters use the clock time corresponding to their time zone.
In some countries, for energy saving purposes, one hour is added to clock time from the last Sunday of March, to the Saturday before the last Sunday of October. This is called summer clock time or daylight saving time, as opposed to winter clock time outside of that period. This is taken into account by Satel-Light whenever clock time is used. The table below presents winter and summer clock time information for all the countries covered by the server.