In case of a power outage (or even a flipped breaker) it's nice to have a backup plan in the house. This setup is also great for off-grid buildings, and could even be used in a camping or job trailer.
In my house, these lights do a good job lighting up the kitchen, living room/hall, bathroom, dressing room and bedroom. They are bright enough to see and get around safely, so one can flip a popped breaker or find the flashlights and candles for a longer emergency. I'll have to test how long the lights can run before the batteries are discharged to the the recommended limit (30-40%).
It's easy to set up. You have a 12 volt battery, a solar panel to charge it, an on/off switch, some LED lights, and wire to connect everything.
Step 1: What You Will Need:
Solar Panel(s) - A few years ago I purchased a couple 2-packs of Sunforce 5W solar panels, the kind used to keep a car or RV battery trickle-charged. I used ONE panel on this project. These run about $40 ea on Amazon.
12V Charge Controller - this is kind of optional for this tiny system, but there are a couple advantages to using a controller. First, you can see at a glance if your system is charging, if it is discharging (there's a load on the circuit), and what level of charge the batteries have. Second, if you want to add more panels and/or more batteries, this controller will keep the panels from overcharging the batteries. I used a Yueton 10A controller (about $10). They also make a 20A for slightly more.
12V Battery (or Batteries) - any kind of rechargable 12V battery will work, including a car battery. In this tiny system, I used a 7AH (amp-hour) by Beiter - these are the batteries in computer backup power strips, security lights, etc.
You really don't want your battery to discharge more than 30-40% max, ever (unless you have a deep-cycle battery). The setup I'm describing here is working just fine for me, but If you're using your light system a lot and your battery is not keeping up, you'll need to add additional and/or bigger batteries and probably larger or additional panel(s) to charge.
Switch - This is just a plain old 12V on/off switch designed for use in a car, boat or RV.
12V LED Lights - I got a string of 10 lights with 4 LED's per light. It was about $18 and included some extra wire. It was called AUDEW 40 Led White Interior Lights Kit on Amazon.
Wire - To do several rooms, you'll need to cut the lights apart and splice in additional wire. 20 gauge wire works fine. I used about 30 feet of it.
Connectors - Crimp-on spade connectors are used to connect wire to the battery and to the switch.
Tools - wire cutters/crimpers, electrical tape, Soldering gun and solder (opt, but recommended), Wire loops and screws (opt)
Please note: all components are 12V - this system does not include an inverter, so it won't run regular household lights or accessories.
Step 2: Set Up the Solar Panel
Find a spot that gets full sun most of the day. Hopefully it's not too far from where you plan on keeping the battery (see next step). If so, you'll need to splice additional wire to reach from the panel to the battery.
Point the panel due south (or as close to due south as is practical. Oh, and if you live in the Southern Hemisphere point it north instead). Then tip the panel back at about a 45 degree angle. This is how you want to mount the panel.
Your panel may have come with mounting brackets or just holes to screw it to something. You can use plywood and a hinge, some scrap wood and some screws to mount your panel at the appropriate angle and orientation, or you can come up with something fancy.
Some people worry about changing the angle of the panel or fine-tuning it to their latitude. Unless you live at the equator or at the Pole, it is really not going to matter that much, especially for this project.
Once your panel is mounted, pull the wire (splicing in more as needed) to where you want to keep the battery. Throughout this process, when pulling wire, use screws and wire loops to attach the wire to the wall.
Note about soldering: It is a good idea to go to the trouble of soldering each splice in the wire. You can do this as you go along, or you can get the system set up and tested, then go back and do it. Which ever way is easiest for your application.
Step 3: Controller and Battery
Site your batteries in a sheltered area, in a weatherproof box, or indoors. Don't use an airtight box, as even sealed batteries could have a little bit of off-gassing. Have them strapped down if possible so they don't get knocked around. You'll want to screw down the controller as well, after you've wired it.
Attach the solar panel's wire to the charge controller where indicated. The one I used had a picture of a solar panel, which made it easy.
Now run a wire from the controller to your battery. If using more than one battery, wire them in series (positive to positive, negative to negative, then one wire each to the appropriate terminals on the controller. Your controller should light up.
Now you'll pull your wire from the controller to where you want your switch. Don't hook up this wire yet.
Step 4: The Switch
Pull your wire inside by whatever route you choose (make a hole in the wall, run it through a window, or whatever). Pull it to where you want your switch, presumably near the front door or somewhere else convenient in the event of a power outage.
To wire the switch, separate the two wires from each other, but do not cut them yet. Figure out which wire you want to be the positive wire, then cut that wire only. Add two spade connectors to each end of the cut wire, then plug in the switch. Go back to the controller and hook up the positive and negative sides to the Load terminals of the controller.
Back inside, you'll want to attach the switch to something - you could drill a hole in the wall or install it in a box. Unless you figure out a fancy way to run the wire inside the walls, you'll just have exposed wiring for this project. (That's what I did.)
Make sure the switch is turned off, then proceed.
Step 5: The Lights
You'll probably be cutting the lights apart and putting one or more in various areas. Make your plan.
Pull your wire to the first location. Look at the lights. With mine, one end was already stripped to show where to start. Note that they will not work if hooked up backwards! So be careful to stay aware which end of the light series is which throughout the process.
Cut the supply wire, then strip and twist your wires to the light. Note which sides are positive and negative, and do this the same for all lights. Turn on the switch - your light should come on. Strip the wire on the end of the light, attach the next length of wire, then peel the adhesive to stick the light in the desired location.
Repeat with the remaining lights. (I tested after each addition, so cool to see them come on).
Step 6: All Done!
Here is the video showing my system working. (I hadn't put up the lights in each room at this point, but I have since then).