Recycling is big at our house (and in our steampunk jewellery store (apologies for the shameless plug, but it does happen to be true - it's all recycled stuff)), and not only for environmental purposes. We love the idea of saving money through ingenuity and a little bit of effort, which is why we're always on the lookout for great ideas on Instructables. Ideas like JoshuaZimmerman's recent Altoids tin solar charger . A superb idea, which I knocked up in minutes from an old emergency charger - I just didn't use the Altoids tin. I simply stuck the small solar collector directly to the back of the existing device.
Building on this great little solar charger, I thought I'd show you a method I use with various solar charging devices for improving their efficiency. I call it the Solar Charger Window Seat.
Did you know that a stationary solar collector -- positioned in a south-facing window (north-facing in the southern hemisphere, natch) -- only gets about four hours of direct sunlight on an average day? By mounting your solar collector on a reflector, you can maximise the amount of sunlight it captures during those essential hours, and pump all that glorious green power into your batteries.
That's what my Solar Charger Window Seat aims to do. You hang it in your window where it's going to start collecting up sunlight from dawn till dusk, sit your solar charger on it, it angles the collector so it's pointing at the sun, and it adds a reflector underneath the solar collector to throw extra sunlight at it.
I haven't recorded my own data on the subject, but I've read that a reflector can increase the efficiency of a solar charger by between 20 and 50 percent. What I have noticed is that some chargers that aren't active on their own (on a slightly cloudy day), begin charging when they're placed on a reflector, so they must be doing something right.
Oh, and this is something you can easily make for free, in half an hour (and that's if you take your time) and is built from easily recycled materials. We like free, don't we?
Step 1: What You Need
>A piece of cardboard approximately twice the height of your solar collector, laid on its side.
>Two paper clips.
Step 2: Cut the Card
This piece of cardboard already had a fold in it, so I made use of that. The bottom of the seat -- which is the reflector -- is approximately 1.5 to 2 times as wide as the collector, so it throws up enough light to make a difference. Don't make it too big, though, or the Window Seat will stick out inconveniently from your window when it's hung up.
Give it a few centimetres either side of the solar collector, so you can attach the string. The back only need to be high enough for the solar charger to rest against it without tipping out. I tend to make it slightly higher than the collector.
Step 3: Cover the Reflector
Lay out a nice flat sheet of kitchen foil, keeping it as smooth as possible to enhance its reflectivity. Bear in mind that most kitchen foil has a shiny side and a matt side - make sure the shiny side is face down, so it'll be on the outside when we stick the foil to the cardboard.
Put the piece of card on the kitchen foil, so you can cut it to size, leaving a few centimetres all the way around. Cut a couple of slits from the edge of the foil to the fold in the card, as this will help to stop the foil from crinkling when we bend the card.
Fold the foil over the card, pulling it as tight as you dare so it's nice and smooth on the other side. Stick it down, covering as many raw edges with tape as you can to avoid tearing.
Flip over the card once the foil is stuck down, and fold it into a nice shiny seat. Don't fold the card too far, as the charger wants to be leaning backwards when it sits in the seat.
Step 4: Attach the Strings
The length of the strings will vary depending on your window. The thing to bear in mind is that if the Solar Charger Window Seat is too near the top of the window, the frame will cast a shadow on it. So the string needs to be long enough to bring the seat down the window where the charger will have a clear view of the sky, all day long. In my case, each piece of string was about 40-cm long, hanging the seat about 20-cm down the window once it was tied in a loop.
Putting some tape underneath the seat to keep the string in place is a good idea - just make sure they're the same length, so the seat is level when it's hung in the window. If your loops of string are a little uneven, you can take up some slack by taping it up on one side underneath the seat (although it's best to wait until it's finished and hanging up to do this).
Step 5: Back Support
Open up two additional paper clips so they're perfectly straight, and then put a bend in them to match the angle you want the seat to be at. Tape one paper clip either side, underneath the seat so it will retain its shape when hung up.
Remember that you want the charger to lean backwards when it's sat in the seat.
Step 6: Window Hooks
You'll need to take a look at your own windows to see exactly what size of hook you need to make from the two paper clips.
Follow the images to see how I fold a hook with a loop on the end for the string to pass through. Don't forget you'll need two.
The paper clips don't have to be as flashy as mine - ordinary ones work just as well, if you're less stylish than I am.
Step 7: Hang Your Solar Charger Window Seat
If needs be, add bits of tape here and there to adjust the string length, and to keep the seat from tipping backwards. The more level the reflector (the base of the seat) is, the better - it'll provide a roughly 45-degree angle to the sun, boosting extra rays onto the solar charger.
Free, easy and very effective. Just leave your solar charger in here whenever you're not using it.
Reap those glorious ray of free power!