Solar-powered Pop-up Paper House




Introduction: Solar-powered Pop-up Paper House

So... Hi! It's Alvin here with his first instructable : ) 
This instructable is on a small project on making a solar powered pop-up paper house. The paper house will convert the light it receives into energy for its interior lighting, lighting up the LEDs inside the house. At the end of this instructable, you will be able to make this very simple little paper toy perfect as a decoration just sitting in your room or as a gift sent to a friend in the form of a pop-up card.

Step 1: Materials Used

So, here are this material used. By material, I am referring to the things that will go onto the paper house. 
  • Pop-up paper house cut out from a 190gsm paper (you may download the pattern in the next step)
  • 2 LED, flat and bright models preferred (I used 1 Red and 1 Blue LED)
  • 14 pieces of 52mm x 6mm small solar cells 
  • Some conductive ink
  • Some instant glue
  • Some copper tape
  • Elmer's glue
As for the beloved tools... 
  • Pen cutter
  • Forceps
  • Random metal rod
Theses are pretty much all the tools you need. Within all these tools, only the pen cutter is truly needed. You may forget the forceps if you think you have nice hands and you can throw away the random metal rod and replace it with a toothpick. 

Step 2: Preparing the Paper Cutout

So, to start with, let's prepare the paper cutout.

The first image is the very simple paper pattern needed in this project. I have the paper pattern prepared by pepakura designer 3, a very handy software for preparing paper pattern. Although it's not a free soft, they offer a free viewer that can display and print their special .pdo files.

For this paper house, you can just download the .jpg file and have the pattern printed onto a thick A4 sheet (around 190 gsm). There are two house in one sheet just in case anything bad happens when you cut out the pattern.

Pay closer attention to the second photo and you will see that one window was not cut out. That window was left there in order to make the inside of the house darker, creating a better contrast when the light is up. Instructions on how the holes on the two roofs are cut out will be found in step 4. 

A dummy house shows how the lower layer of the roof is connected to the house's wall, as well as how the house is flattened. The missing upper roof will be glued onto the trapezoidal flat region of the lower roof later on but, don't do that now as we will still need to do some circuit connection on the roofs first. 

After having an idea of how the house is to be folded, you can now use the pen cutter to create the fold lines along the dotted lines by carefully cutting just a very thin surface layer of the thick paper. This scribing action will aid forming the house's shape as you pops it up from a flat pattern. Note that if you wanna do a mountain fold, you scribe the upper surface of the paper. and if you wanna do a valley fold, you scribe the back side of the paper.  In this model, only two lines on the lower roof and one line at the door need to be scribed underneath. All other lines are scribed on its upper surface.

Step 3: And Here Comes the Solar Panel

The solar panel is what powers the LED inside the house. With each solar cell giving out 0.55 volt max, 7 solar cells in series will give out 3.85 V max. Yet, since only the bottom sides of the first and last solar cell are connected in this connection method, only 6 out of 7 cells are used to power the LEDs. The first cell acts as a dummy cell that gives out no power. The maximum voltage is thus just 3.3 V. One addition more cell will make the LED brighter if you LED can take the extra current but I didn't do so because one extra cell will make a panel too large for this roof.

To connect the solar cells in series, I connect successively the bottom side of a cell to the top side of the other. Solar cells are not that good a conductor. To aid the current flow, bus bar, the more conductive white region on the solar cell, is printed onto the cells. That is why you can see that I am only applying the conductive ink onto the bus bar. After applying 2 dots of instant glue onto the cell edge and a dot of conductive ink onto the edge of the bus bar, I placed the second solar cell onto the first with a 1mm overlapping. Repeat this for 5 more times and you will get a panel consists of 7 cells. Note that the more you overlap, the less of the cell is exposed to sunlight and thus the less current you can get from the cell.

Before I put the panel onto my paper house, I measured its current under a light just to see if all connections are good. My panel gives 80 something mA when not shaded by my fingers but you can still see 57.6 mA when I took the photo with my other hand.

Don't worry too much if the current reads zero. It may only be caused by a bad connection or two. If this happens, identify the bad connection with an aid of a multimeter and use a hot air gun to soften that connection. Then, pull the connected cells apart and redo that connection. You may also simply do another panel from the beginning instead, if you prefer so.

Step 4: Under the Roof

After downloading the .pdf pattern, you will find that the hole in the first image cannot be found in the pattern. That is because I am not sure of what kind of LEDs you are using. So, the first step here is to cut out the holes according to the LEDs of your choice. The edge of the first rectangular hole, around 2mm x 3mm,  shall be around 5 mm from from the center fold line. The second hole shall be cut according to the separation between the two legs of an LED.

Now let's cut out the holes on the upper layer of the roof. The holes near the center fold line shall best be aligned with those on the inner layer for ease of connection. Those holes shall drift away from the center fold line for just a bit due to the paper thickness. Then, use the solar panel prepared in the last step to measure the separation between the two holes on the upper layer of the roof. Holes shall be directly under the first and last solar cell. In the photo attached, you can see that there is a shaded region between the 2 holes on one side of the upper roof. That shaded region corresponds to the second hole of the lower layer. You can then cut out a strip of copper tape of around 2-3 mm wide and connect the holes at the sides and at the shaded regions as shown in the photo. This can then be glued onto the lower roof with some random glue. Instant glue will do this just as well but emer's glue will certainly do a better job. 

Step 5: Time to Play With the Conductive Ink Again

To connect the LEDs to the solar panel, I first apply some Elmer's onto the upper roof followed by some conductive ink into the hole near the edge. I've done a bad example by applying conductive ink at two holes at the same time since it sticks much better when it is wet. It would be ideal to apply conductive ink just before a connection is made.

Then, position the bottom side of the last solar cell of the solar panel to the conductive ink. Note not to let the ink contact with the back side of other solar cells or you will short the solar cells in contact. Remember to flip over the assembly to ensure good positioning. Additional conductive ink might also be added to make a better connection.

When both panels are connected, I flipped the assembly over and dipped the legs of the 2 LEDs into the pool of conductive ink located at the two holes on the lower roof. The conductive ink in the two holes near the center line goes directly to the bottom of the first cell in the solar panel. It is very important have the LEDs connected in the right polarity. A wrong polarity will just give you a dead LED. If you don't know it already, the bottom side of a solar cell is actually the positive side. If you are sticking the solar panel onto the roof in the same direction as I did, the positive side should be the lower end of the panel.

With the LEDs in places,  a complete circuit is formed. I held it under a light to confirm a working assembly before I glued it onto the rest of the house. This step also completes the assemble of this paper house : )

Step 6: Finish!

You are basically done with this paper house in last step. This step is a summary of some optional further steps to take:
  • Additional solar cell
Since one cell is a dummy, the voltage supply is not really enough to power up up a blue LED fully when resistant of conductive ink is taken into concern. Since the LED I used can sustain quite a high current, the house will be much brighter if I can add another solar cell and boost voltage up a bit.

  • Drifted LED position
The two LED hit each other when the house is flattened. This not just hinder the house from flattening, but stresses the fragile solar panel. If a flatter bright LED could be sourced and the two LEDs are offset from the middle line a bit, the house will lie flatter. This will also light up the house better.

  • Encapsulation 
To prevent the fragile solar panel from damage, silicones or 2-part epoxies are nice candidate for encapsulating the solar panel. You may dome the solar panel if you have no intention to flatten the house again. Alternatively, ironing an EVA sheet under a PET sheet will also be a nice encapsulation method that offers some protection to the solar panel. The house may still pops up if you did this carefully.
  • Making a pop-up version
This paper pattern was originally designed to be a pop-up house. Although, this version cannot completely flattened due to the LED thickness and the fragile solar panel, sticking a folded card with the fold line aligned to that of the house's floor will make it a semi-pop-up house. The house will lie as flat as the flat LED you can get.

That's it. Hope you enjoy this paper house and my first instructable : )

Step 7: Let's Pop It Up

So, this is a P.S. section in response to a comment asking about how to make the house a pop-up house. 

Basically, all you need is a thick backing paper of around 20cm x 10cm, with a fold line at the middle and little mark right at the center. Then, apply Elmer's glue to the back of the triangle (marked with a blue dot) and align the edge of that triangle to the center point of the backing as shown in the photo. Then, apply glue to the top triangle and close the backing. Before the glue dries completely, try to open the the backing paper to see if the house opens well. You may need to adjust so a bit due to paper's thickness.

You will still need to put the upper roof and the solar panel on before you can get a good looking pop-up house but as mentioned earlier, the thickness of solar panel and the LED makes this a very poor pop-up house. I suggest you to go for either a pop-up house (with no LED and something else replacing the solar panel) or just solar-powered paper house.

Enjoy : )



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    31 Discussions

    Hehe, using a light to power a light; the first image was my very first thought.

    The next images show my next thoughts - if you could include a pummer circuit, your house would become an automatic solar-powered night-light.

    undoing.pngLO_DarkON pummer circuit.gifpummer.jpg
    4 replies

    Admirable hobby - undoing. Now, for an encore, turn the fan and generator toward each other for a typical perpeual motion (energy) machine.

    Wikipedia: East Anglia is a region of the United Kingdom of Great Britain and Northern Ireland at the level of NUTS 2 for statistical purposes.
    NUTS 2?

    No idea. We're rural, with relatively high unemployment. Maybe that's it?

    Yes! What can possibly be more useless than a solar-powered torch? I find this project quite random too but I still pushed forward this for it simplicity.

    As for the circuit... Never though about this but, woot! Thanks! This will certainly add more usefulness to the whole idea of solar-powered lights. Let's see if i can design something with that. Thanks, man!

    How quaint! I could get my team of estate agents to go and do this for our next team bonding day! It'll be a great project so thanks for sharing!

    To AmyLuthien
    Not harsh at all...if he's going to do something it might as well be useable!!! And for YOUR information, the color can't be change!!!!!!!!
    From: AmyLuthien
    Date: Feb 19, 2013. 12:04 PM

    Being a little harsh, don't you think? If you can't see it, change the color yourself, or put on your glasses, yeesh.

    2 replies

    Well, low lineweight can be a pain for those who are not used to doing papercraft.. Another .jpeg with higher lineweight is added just for you if you fail to see the lines. I am quite sure that photoimpact or programs alike can do the trick but it's not really that troublesome for me to make another version anyway, so, here you go.

    - The color can be changed, of course. So can the lineweight.
    - I did my 5 houses with the original .jpeg file, so.... maybe it's the printer / ink?

    No! Not the printer ink....everyone hasn't got YOUR amazing capabilities!!!
    Doesn't really matter anyway.....

    At first i thought it would be a house that literally pops up using motors or something. XD

    3 replies

    Now that is a brilliant idea ! There are tiny electric motors about 5mm diameter, that run on a very tiny current, like those used in mobile phone vibrators.

    So now just devise a method whereby the motor shaft reels in a cotton thread that automatically pulls the house up into its final shape when it is taken out of the envelope.   Easy enough.  

    That will provide a really impressive effect !

    Any chance that we could do that with a spring of some kind instead? I know that there exist some very weak springs...

    Thinking quickly off the top of my head, possibly some kind of wound rubber band mechanism like in model planes, slowed down by smart grease for dramatic effect.

    Remember "way back when we were kids" the DIY tractor toy with a cotton reel, rubber band and pen ?

    So maybe a small card tube or matchbox, the rubber band going through and fixed at one end, with a matchstick through the other end, could be developed to create a small motor ?

    Perhaps the house is taken from the envelope as flat pack, and a tab is then pulled to activate the mechanism ?

    Hmm, to me, it would make more sense to scribe on the INSIDE of the fold, since that's where the paper is going to bunch up when you make the fold.

    That's what I do when I do leather work, scribe the INSIDE of the fold so that the leather doesn't bunch up in that area when I make my folds.

    The way you say to do it seems a little counter-intuitive, to me. But leather, of course, is thicker than paper, so maybe it doesn't matter as much with the paper.

    1 reply

    Thanks for pointing this out. I am not experienced in leather but I assume "scribing" refers to some kind of material removal in leather terms, does it? Here, by scribing, I am referring to just cutting apart a very thin layer of a sheet. Then, when folded, the outer layer, supposeingly in tension due to fold, will burst out to release such stress instead before the inner layer bunches up.

    I suspect that for leather, a clean surface is much desirable. Leaving a burst outer surface of a fold is very much not desired and material removal of some kind might be performed on the inner layer instead, I assume. But for white paper, bursting out is almost invisible, yet easier to perform. So, for paper, I tend to cut open the outer layer of a fold to prevent bunching.

    Hope this addresses your concern.

    I'm curious about the pop-upping feature. Can you show that in a pic or -even better- a video? Cool project!


    3 replies

    Added the 7th step for the pop-upping feature but, again, I suggest you to go for either pop-upping or just a paper house since the LED might crush the solar panel if you flatten the house too hard.

    Thanks, looks nice! I see how the LED and the solar panel might clash with each other. But the (un)folding of the house looks pretty cool :-)

    Er... Yes of course. I got some extra cutouts in my workplace. Maybe I can take some more photos / video of the pop-up version of this when I am back to work on the 14th.

    So I was thinking you could make a slightly bigger house and embed the guts of the really small solar lawn lights in the roof so it lights up at night. I think they are $1.50 at walmart and they have a stubby AA battery in it. I would do it but I have another flashlight hack ahead of it on my to do list. It’s all yours this week.