For a light on an onshore or offshore fixed structure, first consider the range required. If 5Nm or less then it may be possible to use a self-contained solar powered light, which are simple to install and easy to use and do not need a separate power supply installed. If a mains or solar power supply already exists then a stand-alone light can be used.
If the light needs to be placed in a shaded position, for example under a bridge, then a separate mains or solar power supply will be needed and the solar power supply would need to be positioned in adequate direct sunlight.
The range of a light can be increased by reducing the vertical divergence (beam width). The and VLB-44 have a choice of vertical divergence. The greater divergence is typically used on buoys, to compensate for any rocking at sea, and the narrower divergence on fixed structures. If range is not a key requirement then a wider divergence light can be used on a fixed structure to increase the spread of light at close ranges.
Where mains power is available it is usually chosen in preference to a separate solar powered supply. Most LED lights require a 12Vdc power supply, so typically the mains is used to charge batteries which in turn power the light. The batteries provide a backup in the event of mains power being temporarily lost. It is also possible just to transform the mains down to 12Vdc. When mains is not available then a stand-alone solar power supply is required.