LightingOrdinary light bulbs waste a lot of energy. That's because they work by getting hot; you get a little light and a lot of heat. Change to low-energy lamps and you will probably use about 20% of the power. That means only one fifth of the solar panels, one fifth of the batteries or 80% less spent on electricity for lighting.
Low Energy LampsIf you're on the mains or your solar power system has a big enough inverter, then the best lamps you can use for most things are normal low energy lamps. They fit in a standard light fitting, use about one fifth of the power of a normal light bulb and should last for years.
Low Voltage LampsIf your solar power system is small and you don't have a big inverter, then you will be better off with low voltage lamps. These range from fluorescent strip lights to modern halogen lamps, and are available from caravan and boat suppliers, amongst others.
LED LightingA recent innovation in the field of low-energy lighting is the light-emitting diode or LED lamp. LEDs have been in use for many years as the little red lights in plenty of domestic appliances, but in recent years it has become possible to produce very bright, virtually white output versions. These are extremely efficient and produce virtually no heat.
They are available as direct replacements for conventional and halogen lamps, in both 230 Volt and 12 Volt versions. At the moment their light output is severely limited, so they are best reserved for low level ambient lighting and point light sources. I have no doubt, though, that LED lighting will become a much more serious proposition in the near future.