Project: S.P.R.E.E. (Solar Photovoltaic Renewable Electron Encapsulator), is an experiment in alternative energy and solar generated electricty.The impetus for construction was the desire to have my cellular phone and other small electronics run entirely from free* renewable solar energy.
The goal was to spend the least amount of money possible to design, construct, and maintain a portable, weather-proof, small-scale solar powered battery charger to re-charge any small electronics. Since I live in Southern California, with plenty of sun, the plan is to leave it charging on my balcony during the day, then charge my cellular phone at night. Note: Do not place on a balcony rail like I did, that was just for the picture.
My design was inspired from a do-it-yourself section I saw in Popular Science. The DIY section in Popular Science was a good start, but it lacked complete directions. I did like how article listed how much and where to purchase components.
After reading that article, I searched other corners of the internet and developed my own design. I then researched the project, and gathered the parts for about $160, including taxes and shipping costs. I have friends that own an auto shop, RPM Brakes who let me use their multimeter, soldering iron, and they had plenty of extra connectors around.
I have added several optional modifications in Step 5.
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Step 1: Gather Components for S.P.R.E.E.
The components are very basic, involving a photovoltaic panel, a rechargeable battery, a charge controller, and the sun. You should not spend more that $160, unless money is no object to you. Not the case for me.
5-watt, 12-volt photovoltaic panel, $36, eBay, Solar Cynergy: PV-SC005J17
1/4" mono plug (2), $1, allelectronics.com, SPH
DC solar charge controller, $28, allelectronics.com, SCN-2
12-volt 12-AH rechargeable battery, $40, allelectronics.com, GC-1214
10-feet of 18-gauge wire, $3, allelectronics.com, WRB-18
cigarette lighter "Y" adapter, $4, allelectronics.com, CLP-Y
200-watt power inverter, $17, walmart.com, 001088173
plastic box with split folding lids, $5, target medium bin
wood/hardware for mounting, $4, lowe's, 1x3x4, screws
This leaves about $22 for random parts, upgrades, accessories, shipping fees and taxes.
Necessary tools: Power drill and creativity.
Step 2: Construct a Box for S.P.R.E.E.
I selected a plastic bin with a split opening lid worth $5 at Target. I picked it because it was cheap, durable, easy to modify, and relatively weather-proof. Drill plenty of holes in it to provide airflow. I also drilled holes to add bungee cords to hold the battery secure. And, I drilled a hole for the mono jack to go into the box, leaving the cigarette socket outside of the box.
Be creative. Hollow out an old TV or CRT monitor and use that as your box. Or you can make it out of bamboo flooring scraps like they did in Popular Science.
Step 3: Wire S.P.R.E.E.
The wiring is very simple and intuitive. Basically, the photovoltaic panel and the battery are connected to the charge controller.
The charge controller has a 12 volt output. This output is in the form of a 1/4 inch mono jack. The first step involves cutting off the cigarette lighter plug from the Y-adapter and soldering the mono plug to the cigarette lighter socket. (Since it was a Y adapter, and there was 2 sockets, I made 2 mono-plug-to cigarette-socket "connectors", one as a backup) Make sure to test your connections.
Connect the photovoltaic panel to the charge controller. Insert the 1/4 inch mono jack into the 12 volt output of the charge controller. Check your connections again.
I drilled a hole in the plastic box top, and then attached 2 wooden boards to the top of the box. I then attached the photovoltaic panel to 1/2 inch square wooden dowels. I then created a hinge using speaker wire and screws, which holds the photovolatic panel secure yet allows tilt from 90 to 180 degrees. Then I drilled another hole and inserted the mono jack and left the 12 volt cigarette lighter outside of the housing, but made a holster for it by using a zip-tie.
More about modifications in step 5.
Step 4: Energize S.P.R.E.E.
After all connections have been made ,double check them and test them with a multimeter before connecting to the battery.
Connect the red wire to the positive (+) terminal of the battery, then connect the black wire to the negative (-) terminal of the battery.
Note: The photovoltaic panel will charge the battery even when the charge controller is OFF. The charge controller has to be in the ON position to power 12-volt cigarette lighter socket.
Step 5: Utilize S.P.R.E.E. Then Rejoice in Clean Renewable Energy
Adjust the photovoltaic panel at an angle roughly equal to your latitude for optimum electron encapsulation. Check out U.S. Gazetteer to find your latitude and check your angle with a protractor.
At night, bring it inside, and plug your 12 volt electronics into the cigarette lighter socket to charge. OR, get an DC to AC inverter. It will use some of the electricity to convert the energy, but you will be able to charge AC electronics. Although, it would be more efficient to use DC electronics with this small scale system.
Smile and know that you are using only clean carbon free energy when you talk on your cell phone, take photos with your digital camera, or play PSP.
I have added several inexpensive modifications my S.P.R.E.E.
1. M.A.H.S. (Multi-Angle Height Selector): I sawed up the remaining wood that used mount the photovoltaic panel into 4 different lengths. Then I drilled a hole through each one and attached them all with twine. I also sawed a groove into them which makes the support more secure. Now, I can fan them out and select the right one, depending on where the sun is.
2. L.E.D.P.A.I. (LED Photovoltaic Activity Indicator): I purchased a green LED (with housing) from Radio Shack for $2. I drilled a hole in the top lid and wired the LED in parallet circut with the photovoltaic panel. Now, depending on how much or how little light the photovoltaic panel is receiving, the LED will respond by either glowing bright or becoming dim.
Be creative and be safe, don't zap yourself.