Intro: Super Basic Solar Lighting Under $75
If you are looking for a simple, inexpensive but durable solar lighting setup for your shed or outbuilding then this tutorial is perfect for you. There are many tutorials on this site but we wanted to make our system as frugally as we could and still have a quality setup that would serve most people's basic lighting needs. Our total budget for this whole project was about $75USD and I hope to get many years of maintenance free use from this system. I set up three lights because I love good lighting but this could easily be cut down to just two (interior and exterior) and would work great.
Step 1: Gather Your Materials
I was not just trying to make a cheap solar setup, I was making an inexpensive, durable, practical, versatile, quality solar setup that would last. I'm sure you can find cheaper parts than what I have listed here, but this was as basic as I felt I could go and reliably get a quality end result. You can always order larger solar panels or more batteries but most people only use shed lights occasionally and this setup is very good for around $75. The easiest way to save money is ordering parts online that are shipped directly from China found on various websites, of course the downside of this is that it can takes 4 to 6 weeks for delivery so plan accordingly.
1 ea Solar Panel with Inverter kit. I purchased an Instapark 5W mono-crystalline setup from Amazon for $32. You can find cheaper panels but I wanted to make sure I had one in a sturdy aluminum frame, heavy backing and tempered glass. This is not the best or worst panel out there, just good enough to do the job.
1 ea 12v deep cycle battery, SLA (Sealed Lead Acid), these vary greatly in price depending on your needs but a good basic one can be found for less than $15
1 ea 12v Terminal Block, these can be found on Amazon for less than $4
2 ea 12v switches. These can be found on ebay for as little as $1 ea but may take weeks to ship
1 ea 12v Exterior Grade LED Light. These are in a wide range of styles and prices depending on your taste and budget. I would recommend something less than a 5W. I used a waterproof boat light found on ebay for $8.
1ea 12v Interior Grade LED Light. Again this is available in a wide range of options. I will demonstrate a simple 3W LED fixture that I put together for less than $4 ordering parts from ebay
2 ea Car Fuses and Fuse Holders sized for your system. Also available from ebay for a few dollars.
A few feet of size appropriate Heat Shrink Tape which can also be ordered from ebay for around $1
A tiny amount of Caulk for sealing around exposed areas (this is probably sitting in your garage somewhere)
A Solar Panel Mounting Kit, for mounting the panel on your roof. I'm putting this down reluctantly because it cost $6.99 and it just seems like there must be a more frugal way to do this. You may have a few scrap bolts or some metal pieces lying around you could recycle for this and shave $6.99 off your cost.
You may need some additional 12v Wiring, the kit I ordered came with enough that with a little planning I was able to splice it up for all my wiring needs.
Step 2: Tools
You only need a few basic tools to put this thing together
screw driver with misc bits (the screws on the charge controller are very small)
Solder Gun with Solder
A lighter or matches for heat shrink tubing
Drill and a variety of bits for mounting the panel and drilling holes as necessary
possibly pliers for help mounting some of the lights or the panels
Step 3: A Special Note Before You Begin
If your not experienced with working with electricity this is a great starter project so don't be intimidated. This entire system is 12v and very safe to work with compared to what is in your home. Think of electricity as a river flowing from the positive (+) to the negative (-). The electricity flows from the battery like water but is stopped at the switch that serves like a dam. When the dam is opened (the switch is turned on) the electricity flows through the light bulb lighting the light and back to the negative side of the battery. For this reason it is always important to keep track of which wire is positive and which is negative. These are usually color coded and in our case you can see that the red is the positive and the green is the negative.
The most difficult skill you will need to master is splicing wires which you will have to do at some point during this operation. They make all kinds of fancy connectors that you can buy for this purpose. However since we are trying to build something durable and cheap we will be splicing everything with heat shrink tape and a dab of solder. If you have not used heat shrink tape before then you may want to test out a bit on some scrap wire. Basically heating the tape with flame will shrink it around the wires and keep them nice and tight but don't over heat. Osgeld made an excellent instructable "Master a perfect inline wire splice everytime" which is well worth a read if you have not done this before.
Step 4: Mounting Your Panel
There are many website dedicated to finding the correct placement and angle for your solar panels. I however wanted something discreet so I just mounted at my sheds generally south facing roof angle and close to the edge. Even with my heavily treed lot in the cloudy Pacific Northwest this setup still provides plenty of power for hours of light usage when I need it.
Follow the directions for your solar mounting hardware and remember you will need to screw it into your roof. Rubber washers and a little caulk go a long way in preventing any leaks. I mounted my panel close to where my charge controller and battery were going to be mounted to minimize expose and to be able to use as little resources as possible. I didn't like the hardware that came with my mounting kit so I ended up using a larger exterior grade screw that was long enough to grip into my sheathing and rubber washers between the junctions to seal out any moisture.
Step 5: Mount Your Charge Controller and Battery
I mounted my charge controller and battery close to the roof of my shed where the panel is located. This helps minimize the length of wire needed and neatly mounts the system neatly out of the way but still within reach. It is easy to monitor but I'm not constantly running into it. You will need to cut and strip the wires to mount these.
Step 6: Make Your Control Panel
Your control panel is where it all comes together and this can be as simple or as complex as you need it to be.
In my example I just used a small piece of scrap wood and drilled a few appropriate sized holes for my switches.
On the back you will need to mount your terminal block and run a wire either from the outlet side of your charge controller or directly from your battery. I've seen it work either way but I had several recommendations to run directly from the battery.
I'm showing a photo here of an alternate attachment strategy. Since I'm trying to be cheap I order my electronic parts directly from China and I still had not received my terminal block at this point since sometimes it takes 4 to 6 weeks for shipping. Instead I just spliced all of the wires together and soldered them together and covered with heat shrink tape. A terminal block is not only safer, but it is expandable and I would have to fix this all later.
Step 7: Wire Exterior Lights
There are many varieties of 12v exterior lights available. Usually sold for cars or boats, shop around to find the best deal and style for your application.
In my case I found a waterproof light designed for boats for around $8. I simply mounted it on the outside of my shed. Drilled a small hole for the wire and ran it through the side of the shed (I also added a small bead of caulk here to make sure it was weather tight). Then ran a wire to one of my switches.
Step 8: Wire Interior Lights
Interior lights don't need to be weather proof, but they do need to be sturdy enough to withstand an occasional accidental bumping. The most basic setup I could come up with that would give adequate lighting was to use a 12v 3w MR16 LED bulb and Bi-Pin Socket Ceramic Body, both of which were available for a few dollars on ebay. Obviously there are many choices available here also and for a few bucks more there is a world of 12v car and boat lighting available.
I spliced my wires together and ran them back to my second switch. I then mounted my fixture inside an old tin can and literally made a cheap and sturdy can light. You could wire several of these together around your shed to where you need them.
Step 9: Safety Last!
Safety is always first, but in this case I added a little safety last by adding two inline fuses. I added these last because I wanted to make sure all of my wiring and lights worked and were placed correctly before splicing in some fuses. Some people do not add fuses and I think this is an oversight. 12v systems like this are much safer than what is in most people's homes but adding a few fuses can greatly increase the longevity of your system and its components.
We purchased a few inline 12v fuse holders like those that are normally used in cars. The first one we added between the battery and the charge controller. Even small batteries (like 20Ah) have very high maximum currents that will destroy your charge-controller, so if you have a 20A controller, use a 20 Amp fuse, this can be a (DC) circuit breaker or a regular blade-car fuse between the battery and the controller. These come in many different styles, the one we use here is just an example.
On the output you can either use one fuse between you controller (or battery) for all the lights or multiple fuses for each light. One fuse is sufficient, but all the wiring needs to be able to accept the current rating of that one fuse. If you use more fuses you could use thinner cables, but more importantly, you won't lose power everywhere if you blow just the one. A small schedule can be found here
Step 10: Adding Extras and Conclusion
I kept this system as basic, frugal and sturdy as I could without sacrificing quality. However this system is easily expandable depending on your needs. I added a string of 12v fairy lights to go around my yard for parties ($5 from ebay) but there is an amazing variety of 12v products on the market and low wattage LED's make your power draw very small.
The solar panel is the heart of the system, however it is also the most expensive. My system will give you hours of lighting and is adequate for most people's needs. However adding a larger panel would allow the system to recharge faster if you are using it daily. You can also add more batteries which would allow for more power storage but again this will add more cost and is not necessary for an occasional use outbuilding.
Probably the two most common additions would be a small inverter that would allow you to plug in 'normal' electronics. You could also easily expand from your control panel to add a USB outlet or a 12v 'cigarette lighter' that would allow a variety of additional products to be plugged in. Some charge controllers come with a battery monitor that will let you know how much electricity is still available, its best to not let your battery run below 20% so this might be a good addition if you are using it frequently. I'm probably going to add a 12v motion detecting switch at some point in the future so the lights will go on when I'm approaching.
We developed this system for our budget and Eco-friendly Recycled Modern Shed and have enjoyed hours of light at night from this basic setup. I hope you liked our tutorial and enjoy your own free electricity from the sun!