What 12v bulb uses the least electricity?

Fluorescent lights use less than conventional bulbs, and can be had at any camper supply, or most marine supply stores.

For the least amount of current draw, check into the LED form of lights, as they are the most efficient light available, but I'm not sure if they can be had in 12v.

Electrical power is measured in watts. It is the product of the voltage and the current. The 12 volt bulb which uses the least amount of electricity would have the lowest current. The amount of current depends on the resistance. A 12 volt bulb with infinite resistance would use the least electricity, but of course this would be impractable.

Solar cells generate DC current, but most household appliances use AC current. A solar array will have an inverter circuit which switches DC current to AC current at about 120 volts. In terms of standard lighting, compact fluorescent bulbs are the most energy efficient bulb on the market. However, they may eventually be replaced by high intensity light emitting diodes in the future. LED's run on DC current and nearly all the electrical energy is turned into light. The least energy efficient lightbulb is the standard incandescent bulb. Most of the electrical energy is wasted as heat.

There are 12V flourescents, they're used in automotive applications. But there is inefficiency, as they have internal circuitry to step up the 12V to what the tube needs. Those LED bulbs mentioned above are much superior.

Keep in mind that you can only extract about 20W per square meter of solar cells from bright midday sun. It will take a whole roof full of solar cells and active reflectors to supply the needs of an energy-efficient home, with little power available for heating or cooling.

A single solar panel might give you 60-70 Watt

hours on a good day. (One dim room, 2 Hr.s max.)

You'd get the most light for your watt with fluorescents,

(I don't think there are a lot of LED types available yet),

but one panel won't give you enough light to justify

the effort and expense.

Even larger systems are not yet cost effective.

A burned out 12v light would use the least electricity. 0 amps

LED's would be my choice for a long lasting light source.

all 12v bulbs will use 12 volts as the name would suggest. Some are more efficient than others.

Use energy-efficient bulbs for maximum efficiency. They are a lot more expensive but last for much longer. They waste less electricity as heat than standard bulbs but take ages to warm up to full lighting.

The ultimate in low energy and high efficiency at 12VDC is not cheap but will give you a long life of the lamp and low consumption on your battery. It's the Luxeon technology:

http://www.todae.com.au/comersus2/store/comersus_v...

http://www.yourwelcome.co.uk/acatalog/LED.html

LED's use the least are are pretty available now without too high cost.