More importantly, where will you be if the lights go out--especially if they go out for more than a few hours or a few days? Bear in mind that when I'm speaking of this, I don't mean where in the geographic sense. I mean where will you be--in the dark or in the light?
I'd venture that most people are good to go for a few hours darkness. They have a few candles stashed, and a flashlight or two. Heck, they may even have a working flashlight or two.
Far fewer will have lights after a few days. No matter how carefully husbanded, the batteries get used up and the candles get burned up. As the last little bit of candle gutters, Jack will soon be left in the dark. Not a comforting thought.
There will be those few who have prepared in depth, and have various sorts of lanterns, supplies of fuel, stocks of candles and so on. They will have light for weeks, months or years. But again, no matter how frugally used, it will all be used up. And then, friend survivalist, where are you? In the dark.
Maybe you really prepared in depth, and have stored candle making supplies, and are able to collect fat and render tallow, or you have bee hives where you can gather wax. Or you have some source of vegetable oil, which can be used for lamps. It's a lot of work for not much light, but it's better than being in the dark, right?
But what about electric light? Wouldn't it be great if you had good old-fashioned, before the collapse electric light? Think ahead now, and you can--and you can have it for many years with a little planning and a moderate investment of that green paper we laughingly call "money".
You will need a solar panel, a charge controller, batteries for storage, wire for transmitting the power, and lights to make use of it. All of these things are available now, delivered to your door. You can also buy parts of the setup locally. If you're fortunate, you can buy it all locally.
First, you need to determine how much electricity you need to make. In order to keep the cost down, think small. In this scenario, we're interested in keeping a few lights on, plus some surplus power for ni-cad/ni-mh battery charging. Again, nothing fancy--no TV, no refrigerator, and no air conditioning. No incandescent lights, and very few fluorescents--you're going to living the LED way. This has the benefit of being parsimonious with power, and takes advantage of the fact that LEDs have lifetimes of roughly 100,000 hours. (If you burn an LED for 6 hours per day, it'll only last a tad over 45.6 years. Trust me, the lights will outlast most of the other components of this system.)
Size your panel or panels appropriately. Buy a spare if you can. (Murphy will be livin' large after TEOTWAWKI.) Then buy an appropriate charge controller and a spare for that. Buy a few spools of appropriate wire and suitable fittings for connections and such. Find 2 or 3 RV/trolling batteries and buy them. If you can find somewhere that will sell your dry batteries, buy them and the necessary electrolyte solution (spares, again). Then, hardest to come by, find some strings of LED Christmas lights--white ones, as they will be easiest on your eyes. Assemble as needed.
Depending on your level of handiness, some of this, such as charge controllers, can be home-built. Shop carefully, and you can find many of the other components on sale occasionally. (If you're really frugal, you can find a lot of this used or as salvage.) Work at it, and you'll have a decent small solar setup for $500 or so. Not cheap, but not a budget buster if you do it a bit at a time. And if the worst happens, you'll have lights and enough power for a radio, scanner and a CB/FRS/GMRS/ham setup for communications.
Obviously, this is not meant to be a treatise on solar power. You can Google that up for yourself. But I hope it's caused you to think, and add yet another thing to your long list of supplies to acquire and things to do.