Living off the grid doesn't mean living without electricity, it's more like living without reliable electricity. And without set electrical outlets, light switches and other fixtures you're used to in a modern home, it means moving your lights and lamps around to wherever the electricity is. You might be powering your lights from a 12 volt inverter one day or from a a generator the next. They need to be movable.
Anyone who knows me, knows how many flashlights I have, but the batteries still need to be recharged. Candles are expensive to use as primary lighting, as well as dangerous. No, even a cabin in the woods needs some sort of electricity for lighting.
For about the first month living in the little cabin in the woods, I used a couple mechanic's drop lights. They are cheap, simple and can be moved around easily. But only where you can hook them from. It was a real pain working with the drop lights because wherever and however I hung them, they always seemed to point the wrong way, or twist around to point to the wall. They work great for working on the truck, but not so great as interior lighting.
So, enter the clip-on lights. Still cheap, but they can be moved around and clipped to anything.Not only that, but they have a flexible neck, so they can be clipped wherever you want and then adjusted to point to where you need the light.
Being able to move my lights around proved invaluable. From moving it to the porch when company comes over, moving it to the "bathroom" to shave, or the outdoor "kitchen" for when company leaves and you still have to do the dishes in the woods, I couldn't imagine not owning a couple.
Now I live in a big RV, and my little clip on lights are still with me, and they're still just as useful. Recently I upgraded them to cheap LED bulbs which are even more energy efficient than the compact fluorescent bulbs, which by the way also ran fine off an inverter in the truck. But just like for flashlights, the LED bulbs take efficiency to a new level.