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Build Your Own Solar USB Charger


Have you ever had your cell phone or mp3 player die and you're not close to a computer? In many cases, today's cell phones and other portable electronics use a standard miniUSB or microUSB jack. That means you can use a standard computer's USB cable to charge your phone or mp3 player. This post discusses the components of a typical solar USB Charger.


A USB jack provides +5V DC. The phone or mp3 player's internal circuitry uses this +5VDC to charge the battery. What does this mean for us? Simply that a solar panel USB charger only needs to provide +5VDC - the circuitry needed to charge the device's internal battery handles the charging. That's nice because a charger performs all sorts of tasks like



  • Slowly charging the battery when it is completely discharged until it gets to a point where it can begin fast charging.

  • Fast charging the battery while monitoring the vital signs of the battery like the temperature, voltage, and limiting the charging current.

  • Performing the final top-off charge of the battery - this is usually a low current.

  • Turning off the charger once the battery is fully charged.

  • Performing any maintenance charge. Over time, the battery will naturally deplete called self-discharge (Lithium Ion batteries discharge at a lower rate than NiMH or Alkaline).


  • This article details how to build your own solar power USB charger - a DIY cell phone solar charger.


    Build Your Own Solar Powered USB Charger


    In the diagram above, you're attaching a series of smaller solar panels together to generate a voltage of 7V or more. The string must supply at least 7V because the drop across the voltage regulator (voltage from IN to OUT) is 2V for a standard 7805 regulator. You can choose another voltage regulator that doesn't have as much drop but they are harder to find (not stocked in Radio Shack or Frys) and they're more expensive.


    You'll need to experiment with a capacitor between the OUT terminal and GND as well. Typically a 10uF (microFarad) capacitor is fine. You will also want a capacitor between the IN terminal and GND. Use 10uF for this as well. This is needed to stabilize the +5V output.


    Another option is to buy one of these Solar Panel USB chargers. The ones shown in the following links include a battery so that it is more portable. Contact me if you're interested in the schematic for something like this. I haven't tried the 2nd or 3rd items - the 2nd item gets mixed reviews.



    Simple DIY Solar Panel Project

    I've written a lot about making solar panels at home to save huge amounts on your electricity bill and slash your carbon footprint, all without paying big supply and installation costs. However what if you don't want to take this step right now, instead you just want to have a play with solar technology and see what it can do? Here we present several simple and fun experiments you can do without breaking the bank.


    I'd like to look at the solar garden lights that are spreading everywhere like wildfire at the moment. These are getting so cheap and readily available that you can pick up a dozen for next to nothing.


    A quick search on eBay I did turned up packs at a “Buy it Now” price of $2.95 and I saw plenty of auctions at less than a dollar!!


    Now these solar garden lights don't pack a lot of power really, but they do have a fully working solar cell, a little battery (usually AA size) and a bonus LED light thrown in. Apart from using these lights for their intended purpose of lighting up your garden, you can fire up your imagination and put them to all sorts of great uses. How about using some of the spotlight types over your door so you can find your key at night? What about lighting up the path to the garage so you don't trip?


    These are a few of the more obvious suggestions, but I like to tinker, so if you have some basic skills at wiring, or even better like to hack electronics, how re-using these gadgets for other low power applications? You can make a solar USB charger by hacking together a couple of solar garden lights solar cells and adding a simple regulator. Put enough in “series” (electrical term for connecting together the batteries within the solar garden light units in a daisy chain fashion) and you can build up the voltage a bit. Experiment with a few in series and then connect together a few of your series chains in parallel (another term meaning positive to positive and negative to negative). Series gives you more voltage, and parallel gives you more current and the combination of both can mean more power. Try this; take the guts from a dozen solar garden lights and disconnect the LED lights leaving just the solar cell and the batteries. Divide into two groups of six, connect each group in series then connect the two groups in parallel, now you have a 9V solar power generator than might even run a pond water pump for a pretty display in your garden. Not bad for less than $10 I say.


    I've even seen some modifications using red LED's and a clever arrangement of a lens to make a DIY solar projector which you can use to throw up little projections onto walls outside. Spell out words or simple pictures with your solar projector for a bit of arty fun.



    The best part of all these little solar projects, is that once you have put them together, they cost nothing to run and you can leave them going all the time to continue to inspire you to bring solar power goodness into your life.


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    Do It Yourself Solar Panels for $40

    You've decided you want to build solar panel technology, now you want to find out just how much DIY solar panels will cost. In this article we will do a little experiment – we will go to eBay, do a little searching, find the gear we will need to build solar panel arrays that are equivalent to commercially available solar panels, but at a fraction of the price. We will aim make solar panel of 36 solar cells, which will provide about 18V nominally, enough to charge a 12V lead acid or gel battery.


    We will be searching for WHOLE solar cells, although you can save even more money if you use broken cells – depending on how damaged they are you can still use them, but with lower output.


    I went to eBay, and searched for “36 solar cells” and immediately came up with this entry;


    36 Solar Cells w split 3x6 1.8W 3.6Amp


    Buy It Now $32.42


    Of course this is a “buy it now” type listing, I found many other auctions starting from $1 with just hours to go until bidding stops, so you can pay less than $32 if you try.


    An important thing to note is that the solar cells I have found on eBay and listed above are “untabbed” cells, which means you will need to “tab” them yourself. Tabbing solar cells is not difficult, but you will need some more stuff to get it right. An alternative is to pay slightly more, and buy your solar cells already tabbed, and this will save you time and effort. I found this auction (below) as well, which for about $4 more has the cells already tabbed. Bargain!


    36 FULL Tab solar cell 3X6 B- grade


    Buy It Now $36.63


    Now we have our cells, the rest can be found in the local hardware store – you need plywood for a backing, small cross section timber for the frame, a piece of masonite for the substrate and a piece of perspex or plexiglass for the cover. The best part is, most of these items you can scrounge or reclaim from the rubbish at little or no cost at all!


    I also recommend you grab a copy of one of the guides currently available to help you with the build process. Doing this will save you countless hours, and will make the whole process fast, enjoyable and truly rewarding. Ebooks and information kits are available that include video tutorials, bonus information and tips on putting together whole solar power systems, plus extras light wind power generation and other renewable energy tips and tricks.

    Residential Solar Panels

      Build Your Own Solar Panel – Part 4


      Bringing It All Together and Finishing Up


      Last time we saw how to mount your solar cells within our home built housing and now its really starting to look like a professionally built solar cell array panel. But there's a few more steps before we will be ready to put our solar panel outside.


      First we need to test our wiring, so place the panel somewhere in the light – preferably in direct sunlight, so we can check our panel produces the full voltage. If your are following our example blueprints here you will be building a solar panel which uses an array of 36 solar cells. Each cell produces 0.5V, depending on the incident light so our solar generator will produce around 18V in full sunlight. If you are getting significantly less than this or nothing at all, check the series connections between each solar cell carefully.


      Now, we need to fit an electrical part called a diode in series connection with our solar cells (remember our definition of series connection? - daisy chain one to the next). The diode is essential to prevent your solar panel draining a connected battery during cloudy conditions – it ensures power can only flow in one direction. Your diode should be of a type that is rated for at least 1A (A is short for amp). The diode has a band around it on one end. Connect the end without the band to the positive wire from your solar cell array. Solder on some red/black extension wire to a convenient length. Now I recommend you use a polarized Jones Plug on the end of your cable, but it is not essential if you other ideas in mind.


      Now our panel is electrically complete and working, but we have one vital step left, and that is to fit the plexiglass (perspex) cover over the wooden frame to keep rain and moisture out of our box. Use screws into the timber frame to hold the plexiglass cover in place, however be very careful when drilling the plexiglass, as it is very easy to crack.


      Your solar panel is now ready for action! A solar generator of this size is perfect for charging a 12V gel cell lead acid battery, and the battery in turn can supply all sorts of things. I suggest you let your imagination run wild – solar powered pond pumps, garden lights, and of course all this naturally leads to expanding your system and powering your life and home with cheap, readily available solar power from the sun. When you are ready to take the next step, you can learn ways to use aluminum (aluminium) housings for your solar panels, even cheaper broken or un-wired solar cells that you can get for peanuts or even for free, and how to wire up an array of solar panels, and use inverters and deep cycle batteries so you can generate serious power and use your 120V or 240V household appliances and household lighting with your solar power system.


      This series of articles has hopefully given you a fun and practical introduction into solar power for your home, and detailed, step by step, guides are how I recommend you proceed. Grab yourself a good, well tried and tested guide (they are available on the internet) and don't be afraid to start the solar power revolution in your home – you cando it for less than the big companies will have you believe. Good luck and remember to have fun!


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      Residential Solar Panels

      Build Your Own Solar Panel – Part 3


      Wiring The Panel


      Today we continue our series of articles on how you can slash your electricity bills by making your own homemade solar panel out of readily available materials. You can get into this exciting technology without spending a fortune – in some cases, you can scrounge everything you need to get started. In part 3 of the series, we will take our solar panel housing we made in the part 2 article and get down and dirty with mounting the solar cells onto the substrate.



      And now a brief lesson on electricity and different ways of wiring electrical components up – don't worry – it's very easy. If you are following the suggested sizing presented in this series and are building a solar panel array with 36 solar cells within it you will achieve about 18V from your panel from the 0.5V or so you will get from each cell, and 18V will be great for, say, charging a 12V battery. To get 18V from the panel each solar cell must be wired to it's neighbors in series connection, which means the positive or + from one cell is wired to the negative or – of the next. At each end of your string of cells you will have one free positive wire and one free negative wire, and the voltage between these two wires will be about 18V when the panel is active. The other method of electrical connection other than series connection is parallel connection, and you might need this if you plan on connecting together finished panels so that you still only have 18V but also have more current (measured in amps) produced by your setup. To connect panels in parallel you will connect the positives (+) together and the negatives (-) together of each 18V solar panel.



      Now, back to the action. Depending on the particulars of your solar cells that you have purchased (or scrounged), it may be easier to wire the cells together in series connection before mounting them onto the substrate. If this is the case, make sure you leave enough wire between the middle two cells in the series (between solar cell number 18 and number 19) to cover the distance between the top area of the solar panel housing and the bottom area underneath the central strengthening crossbar. Mount the solar cells individually onto the substrate using one dab of silicone caulk per panel in the middle on the back of the cell. Don't spread silicone caulk all over the solar cell or all over the panel, because the expansion and contraction of the solar cell with temperature may very well crack the cell if it is glued in more than just one central point.



      Make sure you allow at least 24 hours for the silicone caulk to cure completely before any further steps. We are almost done! We just have a few final steps and our fully functional, low cost, solar panel is finished and ready to usher in a new age of cheap available power.



      During the 4th and final article we will put the cover on, finish up the wiring, test the solar panel, and talk about a few options for using your new solar power generation setup, and also improvements you can make for your next project.


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      Residential Solar Panels

      Build Your Own Solar Panel – Part 2


      Building the Frame


      In the second article in this series designed to help you create and assemble a very low cost homemade solar panel at home we will discuss the construction of the housing that will hold our solar cells. We've already covered the basic materials you will need to collect, and now it's time to start our journey towards lower electricity bills and green power generation using solar energy.



      The base plate material you selected will need to be cut down to the basic size to hold the right number of solar cells plus a little room in between the cells and some room for the border or wall construction around the edges that will form a box. Each solar cell is approximately 3 by 6 inches, and as an example we will size up materials to fit 36 cells in an array of 6 across by 6 down. We will use half an inch separation between each solar cell and between the solar cells and the edges, and we will have about three quarters of one inch for the wall thickness at the edges and we will allow for one wall across the middle of the box to help with the strength and to prevent the plexiglass or perspex covering sagging too much. With these numbers you would need 6 x 3” +7 x 0.5” + 2 x 3/4” = 23 inches across and 6 x 6” cells + 8 x 0.5” gaps +3 x 3/4” walls = 42 and a quarter inches total down.



      Cut the three quarter inch square edge timber to size and fix to the base board to form the box walls. You can of course adjust all the dimensions given here to suit your materials you have, but try to avoid making the panel too big and bulky as this will make it hard to mount, and too high walls will affect the efficiency of the solar cells mounted at the edge of our box. Also cut to length the horizontal wall we will install across the middle of the box and fix into place using screws and wood glue.



      Now we have the box ready made we should prepare and paint the surfaces to protect the timber against moisture, as the solar panel will only be useful outside! If you want to build the solar panel to last, you should take great care with this step, and make sure you use several coats of paint and let each coat properly dry before applying the next.



      In the 3rd part of the series on building your own homemade solar panel out of cheap readily available solar cells, we will get to the good part! We will be mounting and wiring up our cells to bring our creation to life.


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      Residential Solar Panels

      Build Your Own Solar Panel – Part 1


      Build Your Own & Slash Your Electricity Bill!


      Putting together a solar panel array for your home and cutting your electricity bills to peanuts or even eliminating electricity bills altogether is tremendously rewarding – both financially and in terms of the achievement and satisfaction involved. Of course you can pay a great deal and get a contractor to do all or part of the work, but putting together your own panels is simpler than you might think – if you have the right guidance. This series of articles will outline the basics involved in assembling a solar panel, with an overview of the steps, from start to finish.



      This first article of the series will deal with the materials and tools you need to build your solar panel at home (don’t worry – anyone could do this).



      Materials

      • A number of smaller solar cells
      • Substrate to mount the cells on
      • Tools
      • Wire

      First, consider the solar cells you are going to assemble into an array. How much you spend on these is up to you, but you can often get chipped or blemished solar cells from a contractor or eBay for very little or even no money in some cases as these are often considered waste. Unblemished and brand new cells are also available in bulk packs, complete with interconnections in some cases. Even brand new cells can be had for much less than the cost of a ready assembled panel.



      You’ll also need a good substrate material to mount the cells on – this is also up to you but masonite or plywood can be good introductory and readily available material you can purchase from the local hardware store. The substrate makes it easier to handle a set of cells, and lets you place the whole lot into the solar panel housing without having to mount each cell individually into the bulky housing. If masonite is used as a substrate, be sure to paint the panel to ensure moisture doesn’t seep into the masonite. The housing itself we will make out of plywood with a three quarter inch square timber frame around the outside. To cover the array, plexiglass (Perspex) can be used. Other materials you will require include Jones Plugs (one of the few specialty items needed – but don’t worry, they are easy to get), Silicone caulk, super glue, some exterior paint for sealing wood surfaces, and some aluminium section or wood to form the surrounds of our solar panel box (ideally about 3/4 inch square, but this is not critical).



      Tools you will need are a hand saw, some screwdrivers, and a soldering iron is preferred, but not absolutely necessary.



      In Part 2 we will assemble the shallow box to hold the cells, and move towards mounting and wiring up our panel.


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