Introduction: "Off Grid" DC Solar Electric Garage Lighting... Hard Wired and Fully Integrated
In this Instructable I will show you how I set up my solar electric garage lighting. I'm using a Fenix International ReadySet Solar Kit to power my lights. During sunny weather the 15 watt solar panel generates electricity and stores it in the battery pack. With a day's charge I can run the DC electric lights in my garage for several hours without having to use grid electricity. I also use the battery pack to charge my iPod through the built in USB port.
I say "Off Grid" in quotation marks because the garage itself is very much on the grid. The only thing that is capable of operating independent of grid power are a few lights in the ceiling of the garage. Even so, the battery pack comes with a wall adapter charger that I have used from time to time to keep it charged up.
One of the great things about this installation is that it is hard wired and fully integrated with the garage. The lights look just like conventional ones that would be installed in your home. All of the wiring is concealed behind the interior sheathing with the exception of the battery pack and a little bit of PVC conduit. If this installation was done as new construction instead of a retrofit I could have easily done without the conduit.
Step 1: A Little About the ReadySet Solar Kit
Instructables was kind enough to send me this neat little solar kit as a prize for being runner up in last year's "Off the Grid Contest".
The kit comes with a solar panel, an intelligent battery pack, a universal USB cell phone battery charger, a wall adapter charger and a 12 volt LED light bulb with power cord.
The battery pack can be charged from either the solar panel or the wall charger from a set of terminals in the back. It has a built in charge controller as well as an alarm that will notify you of an error. On the front of the unit are two 12 volt "cigarette lighter" outlets and two 5 volt USB ports that you can use to draw power. On the front there is also a battery level indicator as well as a charge status indicator.
In these photos you can see the solar panel on a little wooden frame that I built for it. When I first got it I planned on using it for camping trips and emergencies so I made up this portable stand. Now I will make up an aluminum mount and mount it on the roof of my garage with the power cable routed through the roof deck, attic and over to the battery pack. For now I put the panel on the ground beside the shed whenever it's sunny.
The light bulb that came with the kit was particularly interesting. Even though its a 12VDC bulb it has an E26 screw base similar to the ones found on your conventional household 120VAC bulbs. The cord that was included had a bulb screw socket on one end and a "cigarette lighter" style plug on the other end to plug into the battery pack. As strange as the light bulb was it meant that I could install it in a conventional household light fixture as long as it was wired up for 12VDC and not 120VAC. I found more of the same bulbs on eBay and then gathered up some electrical boxes, 18/2 Romex wire, tools and got going.
Step 2: How I Like My Lighting
I built my garage myself and did all of the wiring myself so I have it done exactly the way I like it. Don't worry, I had all of my electrical work inspected and passed. That being said I'll show you how my conventional 120VAC lighting works...
I have one string of eight lights that run around the perimeter of my garage's ceiling. All eight of them are operated by a single switch. Each of these eight lights is a 100 watt equivalent cool white CFL bulb. When they are running the inside of the garage is bright... and I mean burn-your-retinas bright. It's great for when I'm in there working and need to be able to see what I'm doing. I call this my "task lighting". See photo 1.
In the center of the ceiling is a single light operated by another switch. It has a 60 watt equivalent warm white CFL bulb. When this light is the only one burning there is a much softer, much dimmer light in the room. This is good for when I'm unwinding after a week's work, having a beer, surfing the web, etc. I call this my "mood lighting". See Photo 2.
My solar powered DC lighting works on the same principle as my regular lighting. I have one switch that controls four cool white LED "task lights" around the perimeter of the ceiling and another switch that controls a single LED warm white "mood light" in the center of the ceiling.
Step 3: Mounting the Battery Pack
I built a small shelf on the garage wall that was close to the breaker panel and had easy access to the attic. I put the ReadySet battery pack on that shelf.
Above the breaker panel is an access hole where all of the branch circuit wires pass through the ceiling and into the attic. I left this hole open so that in the future I could easily pass cables from my roof mounted solar panels down through the ceiling and into a power inverter located near the breaker panel. The power cable from the ReadySet battery pack enters the attic through this hole.
The other reason I mounted the battery pack in this location is because it is close to the door. If the battery pack hasn't been used for more than half an hour you must wake it by pressing the button on the front of the unit. If the unit is close to the door then you don't have to grope through a dark garage to turn on the lights. When you first walk in, simply press the button on the front of the battery pack then flip the solar light switch.
Step 4: Connecting to the ReadySet and Installing Circuit Protection
The ReadySet batter pack connects to the rest of the system via the 12 volt "cigarette lighter" plug on the front of the unit. I bought a 12 volt socket extension cord and snipped off the female end to get the "pigtails". In the first picture you can see the "cigarette lighter" plug on the front of the unit with the coiled cord leading into the grey strain relief connector at the bottom of the conduit box.
Inside the box, the incoming coiled cord is wired to a 3A automotive fuse and is then connected to the red 18/3 Romex cable that exits through the top of the conduit box. The Romex cable travels straight up into the attic where it goes into a junction box up there.
I should mention that this step and onward involves electrical wiring. If you want to attempt to do this please know what you are doing. This project involves only low voltage wiring and does not present a significant electrocution hazard. However, a short circuit or overload anywhere in the system can still cause the wires to heat up to the point where they can start a fire. It's important to properly size your wiring and have a fuse or circuit breaker installed to protect the wiring. If the last few sentences are a new concept to you then please ask me for advice and brush up on your circuits homework.
Step 5: Wiring Up the Lights
As soon as the power supply cable passes into the attic it heads straight for the junction box that you see in the first picture. In the junction box there is a simple splice connection that splits the power supply cable into two circuits. One of the circuits is for the mood light and the other circuit is for the task lights.
The mood light cable goes into the mood light fixture. The task light cable goes into the first fixture of the task light string (there are four fixtures in this string).
In the second picture you see the fixture for the mood light. The power cable coming from the attic junction box is the one without the green masking tape on it. The cable with the green masking tape goes out to the switch. The way this is wired allows the positive wire from the power cable to be fed out to the switch before it comes back to power the light bulb. This type of wiring is called a "live loop" and is common in household 120VAC lighting circuits.
For the task lighting, the first light fixture in the string is wired similar to the mood light. There is a live loop that carries the positive wire out to the switch before returning to the light. The only difference is that instead of the two empty screw terminals on the light fixture like you see on the mood light there are connections for the cable supplying power for the rest of the lights on that string.
The fourth picture shows a light in the middle of the task lighting string. You can see how it is easy to "daisy chain" the lights by wiring up the screw terminals in parallel.
Step 6: The Light Switch
Each of the two light circuits have a cable that runs into the conduit box you see in the picture. Because each cable is part of a "live loop" the switch just has to connect the two wires from each cable together to close the circuit and turn on the light. I bought a double light switch to save space on the wall next to my door. It's simply two separate switches that fit into the space of one.
Double switches will often have a brass colored tab between the two screw terminals on one side. This tab must be broken off to make the switch work. It's okay to break off the tab with a pair of pliers, the tab was meant for it.
Step 7: Testing the Light Fixtures
With the battery pack on and both of the switches closed each light socket should read about 12 volts DC. The positive terminal should be the brass strip in the center of the socket and the negative terminal should be the threaded portion. If it doesn't read exactly 12 volts then that's okay. 12 volts is just the nominal voltage of the battery but it could be anywhere from 10 to 14 volts.
Step 8: Enjoying the Free Electric Lighting
Ever since I had these solar lights installed I barely ever use the 120VAC ones. Even when the battery pack runs low on charge I just plug it into the wall outlet with the supplied adapter.
I haven't gotten around to it but I will mount the solar panel to the roof of the garage when I get time to make up a mount out of aluminum.
If you have any questions please feel free to ask about anything at all. I you liked this Instructable please vote for me in the "Battery Powered" contest. As always, thank you very much for reading.