I have two Phillips brand porch lights from Home Depot that use a photo switch and a 13 watt self ballasted cfl.
26 watts 14 hours a day, call it 2.5kwh a week, or 10 kwh a month. That doesn't sound like much power, but because I am on batteries as much as possible, it's actually 1/3 of my monthly consumption
from the grid.
The Phillips brand porch light is more reliable than the Lights of America brand it replaced but puts out much less usable light. Corkscrew cfls don't have anywhere near the light output efficiency of linear fluorescents. The LOA lights had a 13 watt instant start biax tube and a fancy circuit board. The photo sensor was instant, so it flickered at dusk and dawn and the circuit board was accessible to bugs and humidity. The housing design was so poor, the photosensor would see it's own light and flicker off/on from that, too.
Not being happy with either design, I decided to experiment. There are no cfl porch lights with a built-in sensor at Home Depot that use less than 13 watts. I only need to see the door in the dark, not light the whole court yard where I live. There were also very few choices at HD for self-ballasted LED lights with Edison bases. There are a lot of LED track light substitutes for 12v halogen spots. A spot beam is what LED's do well, but I didn't want to run wires from my bank just to run two porch lights.
HD has one cold-cathode cfl that uses 5 watts. They are candelabra based with an Edison base adapter. They look like chandelier bulb replacements, since they are dimmable. Better still they have a rated life of 20k hours and cost the same as a regular cfl ($13 for a 2-pack).
The Phillips light has a special twist-lock base for lamps it uses, but the base is simply held with two very small screws. I replaced it with a ceramic lamp base intended for a floor lamp. The ceramic base has wires attached already and costs $3, so the cost per fixture to mod is only $10 total, and no drilling or cutting is needed.
The two thumbnails pix are before and after. The full sized pix are at the links below.
http://i269.photobucket.com/albums/jj62/dnix71/IMG_0153.jpg?t=1278344890http://i269.photobucket.com/albums/jj62/dnix71/IMG_0154.jpg?t=1278344890The 5 watt fixture is nowhere as bright as the 13 watt original, but it works just fine for what I need and if the lamp actually lasts 20k hours as claimed it will be a long long long time before I need to think about this again.