Low voltage lighting is powered directly by the batteries. The advantages of this type of system include:
High efficiency: Using low voltage flourescent and halogen bulbs, satisfactory results can be obtained with very little electricity. Reliability: With a DC lighting system, the lights can be operated until there is no more electricity in the battery bank. Period.
In houses with an AC wiring system, separate wiring runs must be made for the DC lights. Long wire runs must use a heavier guage wire than their AC counterparts. DC lightbulbs and compatible fixtures are more limited in variety and typically more expensive than AC types. DC lightbulbs are not as readily available as 120V AC bulbs. in many areas, replacement bulbs must be ordered in.
The advantages of AC high voltage lighting include: There are a wide variety of readily available lamps and fixtures located in your local hardware store. Easy installation using off the shelf components. Easy code compliance Components for AC wiring systems are relatively inexpensive. Long wire runs are no problem.
Disadvantages: Relatively lower efficiencies than DC systems In an otherwise all DC system,installation of AC lighting would require the purchase of an inverter.
DC lighting is preferrable in small systems, but AC usually proves more cost effective for medium to larger systems.