S.P.R.E.E. (Solar Photovoltaic Renewable Electron Encapsulator), a Compact, Durable, and Portable Solar Energy Generator

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For under $160 you can construct a S.P.R.E.E. to harness clean carbon-free solar electricity to power your portable electronic devices.

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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This is awesome! Cheap too.
youcantoo2 years ago
For your adding a activity LED. You should of added a current limiting resistor in ine to your LED to prevent it from burning out from over current. Some simple calculations would show a 470 ohm resistor should be fine. As for your last comment about not zapping yourself.... This is a 12VDC system and they should be no electrical shock, but it is a good thing to remember to not directly short out the battery as it will draw maximum amperage and would indeed burn up the wiring and anything else it maybe touching. A really good idea would be to place a fuse in the circuit as close to the battery positive terminal as possible. It this case a 10 amp fuse should be fine. This would let you draw up to 120 watts of power from the system and would prevent a short circuit from burning up the wiring or causing a fire. Think safety first and foremost!
If I used this along with a car battery or motorcycle battery then I have free power for all of my gadgets.

This plus a small cheap $5 inverter (with usb output) nets me FREE clean power.


I would not need a solar charge controller with this unit either.

Can someone please confirm my thoughts here.
If you hook any solar panel without a charge controller you run the risk of ruining your battery(s) in a short time due to overcharging. This is just a plain bad practice. Always use a charge controller with solar or wind powered systems. Also not that it is NOT a good idea to use a automotive type of battery or motorcycle battery. They are not designed to hand the charge/discharge that happens with a solar/wind system and will not last long. Use a deep cycle battery which can handle such charge/discharge cycles. For example a marine or RV battery etc.
Noblenutria4 years ago
Don't you need around 14.8 volts to charge a 12 volt battery? Usually the voltage of the panels are higher than the voltage of the battery. I looked at the specs for the charge controller. It says it works with an open panel voltage of 21 to 24 volts. Your panel is 12 volts.
Most panels have an open charge/panel voltage of 18 VDC. (meaning no load) so there is no problem using it with the controller.
rookie16 years ago
Good job! How big would things have to be to run a shop of house on this? Or maybe just a heater or fan/air conditioner for a shop?
Heating with electricity is the most wasteful way to heat. Every KwH of electricity you pump in gets you the same amount of heat out, so it's 100% efficient. HOWEVER, it's described as cutting butter with a chainsaw: you're using a high grade of energy for such a low grade job. Look into a solar air heater, which instead of using electricity to power a heater, sucks in air inside a big box on the roof outside which the sun heats. The warm air then goes back inside. It is much more efficient and actually makes sense.
One of these would be good for several fans, assuming under 100W per fan:


This without running the fan during nights. If you need excess energy to be released during the night, then the panel obviously needs to be putting out more wattage (plus a proper battery bank).

But for a AC you would need several more. If an ac-unit is around 1500W (approx, here close to the polar circle we do not have need for AC :), then the panels need to put out more than 1500W, especially if you intend to run the AC after the sun has set (or is too low for effective production of electricity). and then you need a decent set of batteries (€€€) to storage the energy, and a charge controller (€€€) to cope with the currents.

1500W in those panels above is over 3000USD. And 1,5kWh costs here 15 eurocents. The electricity coming out from the wall outlet is still so cheap there is relly no way to produce it cheply yourself... Altohought I'm still looking for some panels myself, to make a waterheater, but then I need to scavenge the panels from somewhere cheap :).
UQONYX4 years ago
to make a simple sun tracker, you can take an old clock and go to a clock store or somewhere and ask to switch the gears to metal, then attach the panelto the hour hand/ pivot so that it turns a little as the hours move
You may or may not be interested but "Spraoi" is Gaelic for Fun, and is pronounced the same as spree!
hemanath4 years ago
I want to know how silicon solar cells are manufactured
Ole bally4 years ago
Hey Charlitron, I live in a country where we can't just transfer funds and so I'm doomed to not be able to become a Pro Member!
Have you or any of the other members ever looked at the 'Henry Moray' website or the Tesla site? This is about FREE electricity using 'cosmic energy'! You Pro members on this site are jut the people to give this thing a proper try and tell us all if it really works! Tesla and Moray were pioneers in the energy field! Please have a look and give me yr comments!
vcampos20007 years ago
I am new to this: How do you know which wire is positive and which is neutral? I know the mono jack terminals are marked but I don't see any markings on the cigarette adaptor.
charlitron (author)  vcampos20007 years ago
I was also new to this a few months ago. For the mono jack, the tip is the + and the sleeve is the -.
For the cigarette adapter, there is also a similar 'tip' (which looks like a little button on the end of the cigarette adapter), and a similar "sleeve" (which are the side metal contacts of the cigarette lighter). Before I snipped the cable, I stripped the cable right next to the cigarette adapter and traced the wires and marked the tip (+) with tape. Then it was easy soldering, which I was self taught with the help of some youtube guy
What did you do with the Amp meter? I saw it in th photo but not in the finished project.
charlitron (author)  vcampos20007 years ago
I bought the 15-amp DC panel meter ($12), but then returned it to save costs. I decided it was not necessary and not a vital component to the system.
Try investing like a volt meter but in this case since you have a charge controller it's unnecessary. I would carry one in case if there's any problems with it

I'm planning a large scale for backup
Volt meters can be purchased at hardware stores for under 15$ I found one at Home depot for 9.99. Everyone who works with power should have this basic tool. It can tell you if you really turned off the power to a wall socket.
Hi there, about the soldering. I see that you just took one wire and soldered it to the part of the plug for the signal wire in a music cable, and one wire to the part of the plug that is for the ground wire in a music cable. does it matter which is which for the cigarette socket. How did you know which wire to solder to which part of the plug? thanks! I'm building mine right now!
Get a multi meter. Connect the leads and touch a test lead to one side of the circut and one to the other. If its a digital guage it will show a plus or minus on one side of the reading. If it is a - it means you connected the meter backwards and the multimeters test lead + (or red) is on negative voltage in a DC curcit.

Cig adaptors are standard. The center nub of the mail and female cig plug is positive. This should be on all systems. pinouts.ru is a good place to get this kind of information.
Sielock5 years ago
I am a little confused with the mono plug, is there advantage to that over using the load terminals on the controller?
I built this last year with all the recommended components but like a previous post my battery does not seem to be charging.  I have my solar panel in a southeast facing window so it gets a lot of morning sun but still no luck.  do I need more sun?
Test it with a multimeter. Maybe you have a short.
nepheron5 years ago
 Here's mine: 

It's 5v .46 amps ( USB charger)
bmnot5 years ago
Very indepth instructions.
However, I have one question

How does the dc panel meter connect to the setup?
 hmmmmmm i dont know were to get any of that lol
Does this type of battery need to be kept upright? I would have to turn the case sideways to make it portable.
what if I have a 12VDC to 115VAC POWER INVERTER?  350W Continuous.  I found one and would rather not buy a 200W inverter if necessary
knektek5 years ago
Excellent project! couldnt of you just used a 12vregulator to make sure you dont burn out the output
jugome5 years ago

sunami5 years ago
how can i make this into a science fair project
jensene66 years ago
Will this setup charge the battery if it is totally dead? I built this and it worked fine for a couple days but now the battery is reading low about 10.5 volts and even when I leave it in the sun all day it doesn't seem to change anything.
patdoherty6 years ago
very cool but it is inefficient since your stepping up the power to 120 ac then stepping it down to whatever your cell phone is it would be better to plug a car phone charger in
nice but i dont think that the charge controller is needed with only a 5 watt solar panel.
charlitron (author)  rocketman2217 years ago
You know... I was wondering the same thing when I was planning my design, especially since price was a big factor for this project. The charge controller ($28) was the third most expensive component. But, I ended up getting it for 2 reasons: First, for the utility, there was a main control switch and all of the on board connections. Second, my good friend that lived 2.5 years off-grid in Bethel, Lesotho recommended a controller to increase the longevity of the system.
I also buult this off the PopSci article, and it worked fine at first. However, when I went to go use the solar charger on Friday and the battery was flat. I didn't really have it in the sun for the past couple of weeks and I used it to charge up a few things, so I moved some stuff around so there was a place right in front of the window. Sunday morning I go check the battery. Still flat. I'm like, WTF. So I dig out my meter and test the battery posts. 10 volts. That's basically dead for a 12v battery. I pull out the charge controller which has been on since the beginning and tested the connection screws. Battery connections: 10v. Solar panel connections: 10v. Meter connections (which measure power output): barely a twitch. I turn the meter dial from the 50v setting to the 10v setting and test again. The output is at barely 0.5v. So I turn the charge controller off. Now when I measure the solar panel connections I get 21 volts! So I leave the controller off and let it sit in the sun all day (the manual on the controller said it would charge the battery even when off, just not allow power output). End of the day, the battery is still flat. Yes, the fuse is fine. I'm at a loss. Any suggestions? If you look at the bottom right of the controller, there are 3 screw connections: Negative, positive, positive for the solar panel connections. Why are there two positives? Am I missing there or is this controller just faulty? It did a fine job of routing power from the battery out, but if it's not charging at a voltage higher than 10, it won't actually recharge the battery. Any nerdly advice?
I have to agree that the charge controller may not be need in this application. Yes in an off-grid installation, charge controller is critical, but you wouldn't be using a >$30 controller. Anyway you now have an usable controls that will allow you to add capacity.
your friend lives off the grid in a country...that itself is in another country... AWESOME!
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