Emergency USB Solar Wall Socket: Solar Socket




Introduction: Emergency USB Solar Wall Socket: Solar Socket

About: After being laid off in 2009, I got rid of my car to save money. The difficult transition from a car to a bicycle led me to start Solarcycle and design USB chargers that keep smart phones alive.

Please click below to visit our Kickstarter project page to pre-order a production model!


The first ever solar powered USB home wall socket for emergency and everyday use!

"Plug into Independent Power." When the power grid goes down unexpectedly, stay powered and connected! Bring the power of the sun directly to your smart phone!

Emergency back up power - Solar Socket is something home owners have been looking for; a solar panel and backup battery for USB devices that is low cost, powerful, and easy to install! Your Solar Socket battery system will provide your home with USB power when the power grid goes down after an earthquake, storm, or other natural disaster. When the grid goes down, don’t be left without power!

Stay powered in a pinch – Keep your phone charged to stay in touch with loved ones, get the latest news, and receive alerts and essential information. Keep the lights on by charging your USB lighting devices such as LED flashlights, headlamps, and lanterns. If the grid is down for days or weeks, the sun will keep charging your devices.

Solar Socket Solar Panel Specs:
* Size: W 6.5 inches X L 10.9 inches X H 0.6 inches

* Cable Length: 10 feet * Weight: 270g (9.52 oz)

* Nominal Output - Current: 1000mA 5 Watt) | Voltage: 5 Volts * Max Open Circuit Voltage: 6 Volts

* Cell Type: Monocrystalline * Cell Efficiency: 18.8%

* Compatible with Solar Socket

Solar Socket USB Wall Plug and Battery Specs:

* Time to Fully Charge: @5 Watts 6700mAh: 6 hours

* Capacity: 6700mAh / 3.6V

* Type: NCR18650B Lithium-Ion

* Weight: 386g (13.6oz )

* Input - Current: 450 to 2600mA | Voltage: 5 to 6 Volts

* Number of USB Ports: 2

* Output - Female USB 2.0 Type A Connector

* Output - Current: Up to 1400mA | Voltage: 5 Volts

* Body Material: Standard Drywall Electrical Box

* Battery Life Under Typical Use: 5 years * Replaceable Battery

* Provides up to 320% iPhone Charge or 160% Galaxy S5 Charge

* Compatible with iPhone, Android, Windows Phone, and Others

*WARNING: Be careful when handling any Lithium-Ion battery because shorting the battery can cause burns. Always wear safety goggles. Please use recommended battery and circuit components because of the higher 2000mA max battery charge current involved. 3D printed parts may warp under high temperatures.

FCC Compliance: NOT Required because the circuit frequencies are below 1.7MHz

Step 1: Materials, Tools, and Files Required

Here is a list of the materials, tools, and files required.


QTY Description

1 Generic metal bracket from a hardware store (Example http://www.homedepot.com/p/Crown-Bolt-Zinc-Plated-...)

1 Solarpad Bracket http://www.shapeways.com/shops/Solarcycle
2 Solarpad Edge Trim http://www.shapeways.com/shops/Solarcycle

1 Solar Panel (Layout Drawings can be downloaded at http://www.solarcyclepower.com/index/Open_Source.h... Suntactics solar panels are recommended because they have the highest verified power output. You can try to cut your own solar cells using this instructable https://www.instructables.com/id/Ultra-Portable-Dre... or you can contact www.suntactics.com to build one for you. You may have to supply some materials to Suntactics for a few prototypes because they are not off-the-shelf products yet.) 1 Stainless Steel 1/4-20 Nut (The thinner nut height the better http://www.mcmaster.com/#stainless-steel-hex-nuts/...)

1 Drywall Electrical Box

1 USB wall socket face place http://www.vetco.net/catalog/product_info.php?cPat...

2 Lithium-Ion Charge Controller Circuit (Schematic, Gerber Files, etc. can be downloaded at http://www.solarcyclepower.com/index/Open_Source.html The main IC components are the Maxim MAX8903G charge controller and MAX1790DC-DC step-up converter circuits)

2 NCR18650B 3350mAh Unprotected Panasonic Lithium Ion Battery www.ebay.com (If lower cost is necessary, try the Panasonic NCR18650A battery with a slightly less capacity of 3070mAh. Make sure it's unprotected and check the battery part number carefully. Protected batteries have added length with a built-in circuit, which may affect performance. Reference http://industrial.panasonic.com/www-cgi/jvcr13pz.cgi?E+BA+3+ACI4002+NCR-18650B+7+EU Other brands of batteries are NOT recommended because the charge controller current to the battery can be as high as 2000mA and the Panasonic NCR18650 chemistry can handle it. If you need to use other brands, make sure that they meet the same specifications, chemistry, and can handle up to 2 Amps of charge current. Using batteries that don't meet these specifications can lead to dangerous battery damage.)

2 Blue 5mm Straw Hat LED www.ebay.com

4 Hirose 2-pin connector DF3-2S-2C http://www.digikey.com/product-detail/en/DF3-2S-2C/H2083-ND/141479

4 Hirose 4-pin connector DF3-4S-2C http://www.digikey.com/product-detail/en/DF3-4S-2C/H2085-ND/141485

20 Hirose Socket 24-28 AWG Crimp Pin DF3-2428SCC http://www.digikey.com/product-detail/en/DF3-2428SCC/H1501-ND/269904

3 3' USB Male-Female USB 2.0 Type A Extension Cable (Cable drawing can be downloaded at http://www.solarcyclepower.com/index/Open_Source.html)

1 10" USB Male-Female USB 2.0 Type A Extension Cable

1 Roll of double-sided tape

1 Roll of electrical tape

1 1" Wide Kapton Tape Roll www.ebay.com

4 1" Kapton Tape Disc www.ebay.com

2 1" Diameter Piece of Heat Shrink Tubing 2.7" Long

4 1/16" Piece of Heat Shrink Tubing 1.0" Long

1 Roll of solder wire

Various Lengths 26 AWG Standard Red and Black Stranded 4 Amp Max Wire Listed Below: http://www.mcmaster.com/#catalog/119/798/=qu7rf6

2 6.10" Black Wire .06 strip one end .20 strip the other end

2 8.00" Red Wire .06 strip one end .20 strip the other end

2 3.1" Black Wire .06 strip one end .20 strip the other end

2 3.1" Red Wire .06 strip one end .20 strip the other end

1 Phillips head wood screw 1" long

1 1/4-20 phillips head bolt .5" long


QTY Description

1 13/64" drill bit

1 Phillips screw driver

1 Power Core Battery Fixture https://www.shapeways.com/shops/Solarcycle

1 Wire Strippers 24-26 gage range

1 Wire Crimper 20-24 gage range

1 Tape Measure

1 Third Hand Soldering Clamp

1 Soldering Iron

1 Heat Gun

1 Scissors

Step 2: Solar Panel Assembly

If the solar panel doesn't come with 6 holes that line up with the plastic edge trim and body, you can make the holes by inserting the trim in to the body slots, clamping the solar panel to them and drilling out the holes with a 1/8" drill bit. These will be the holes for the rivets during final assembly.

Cut one of the USB cables 21" from the female end. Strip the outer jacket .5" from the end, remove the shielding, and strip the Black and Red wires about .25" from the end. Cut away the Green and White wires because they aren't needed.

The back of the panel should have two leads. To verify the polarity, just attach a Volt meter to the leads and shine a light on the panel. Positive voltage means that the positive and negative leads are in the correct orientation. (I've had a panel with reversed orientation, so it is always good to check before soldering)

Bend the leads to the side and place Kapton tape on top of the exposed leads that are not being soldered to. This protects exposed leads from moisture. You can also apply epoxy to them, but it would take more time. (Having the USB cable come out from the side creates a service loop within the plastic body giving it a retractable cord effect)

Solder the USB Red wire to the positive lead and the Black wire to the negative lead. Push the leads down to be flat as possible. (When the panel is attached to the plastic body during final assembly, you don't want the epoxy on the leads to hit the 1/4-20 nut)

Build a Kapton tape wall around the soldered leads and cable with about a .25" gap around the leads. This wall will contain the epoxy, which acts as a water sealant and cable strain relief. Make sure some of the cable jacket is within the Kapton wall to make a good strain relief.

Place the 1/4-20 nut inside the plastic body on top of the large hole in the center. Build a Kapton wall around the nut with about a .25" gap and don't let the tape touch the nut. Be sure to center the nut on the hole.

Attach the mixing nozzle to the applicator gun. Ideally you want to use an applicator gun for this step to get in to the tight spaces. It may be possible to do it without an applicator gun, but it might take a longer time and be more messy. Either way, be sure to have a few sheets of plastic to do work over and to rest the epoxy applicator down on to catch any epoxy spills. This epoxy has a working time of only 5 minutes and hardens quickly, which is why all the parts are prepared for epoxy first. Try to keep the epoxy flowing in the nozzle or it will harden inside prematurely and you have to replace the nozzle. As it hardens, the epoxy does get hot, which is a normal exothermic reaction. If epoxy spills on something, be sure to clean it up right away before it hardens. Also, epoxy can give off a strong odor so be sure to work in a ventilated area.

Fill the Kapton walls with epoxy so that it barely covers the wires and just up to the 1/4-20 nut. Fill the LED Cap pockets with epoxy making sure the tie wraps are in the pocket. (A cardboard box with a thin cut groove works well for holding the cables in place.)

Put a bead of epoxy all around one end of the aluminum tube and slide the Power Core Cap on while twisting the cap at the same time. Twisting the cap allows the epoxy to evenly spread out and you should end up with a nice bead around the cap. This visible bead ensures that the water seal is good.

Remove the Kapton tape walls while the epoxy is still rubbery and you should be left with a good epoxy encapsulation. Check that no bare wires are exposed and that the 1/4-20 nut is secure. If you think the solar panel cable needs more strain relief you can add some more epoxy on the cable jacket.

Remove the mixing nozzle from the applicator and put the cap on the tube or it could seal the epoxy inside the tube.

After 10 minutes the epoxy should harden, but may still be tacky and rubbery so don't touch the epoxy. At this stage, place the solar panel on top of the bracket to make sure that the epoxy globs don't interfere with each other. If they do, you can trim excess epoxy away with a knife. (To get the retractable cable effect, make sure the cable coming out from the solar panel is facing away from the slit in the middle of one edge of the bracket. The cable should loop around inside the bracket creating a service loop)

Step 3: Battery Assembly

Insert the NCR18650B battery in to the Power Core Battery Fixture with the positive side facing up. The fixture will align the Red and Black wires as you solder. Do not touch the soldering iron to the fixture because it can melt. You might be able to solder the battery without the fixture, but it is much harder and you would still need something to keep the battery from falling over. The fixture can be used for other battery projects too.

Place the .20" stripped end of the long Red wire in the trench labeled +RED and solder the Red wire to the battery. Try to solder to the battery quickly because too much heat to the battery may damage it. If there is any solder sticking out, smooth it out with the soldering iron.

After soldering, tilt the fixture and push the battery out from underneath with your finger. Turn the battery upside down and insert the battery in to the fixture with the Red Wire in the +RED trough and the negative end of the battery facing up. Crimp the end of the Red wire with the Hirose Pin and insert the pin in to port 1 of the Hirose 2-Pin connector. You want to attach the connector at this point because it is dangerous to leave a dangling bare end of a battery wire exposed and can potentially cause a short or burns if it touches the negative end of the battery. Place the .20" stripped end of the long Black wire in the trench labeled -BLK and solder the Black wire to the battery. The negative end of this battery usually requires more heat to solder because there's more surface area in contact with the mass of the battery, but try to solder quick. If there is any solder sticking out, smooth it out with the soldering iron.

After soldering, crimp the end of the Black wire with the Hirose Pin and insert the pin in to port 2 of the Hirose 2-Pin connector. Tilt the fixture and push the battery out from underneath with your finger.

Bend the black wire straight down over the edge of the negative end of the battery and guide the red wire to loop around along the side of the battery. The effect should be that the Red wire coming down from the positive end of the battery is 120º apart from where the Black and Red wires meet. This wire geometry allows for the positive and negative wires to come out from the same side and gives the snug fit inside the aluminum tube without any glue.

Wrap a piece of 1" wide Kapton tape once around the middle of the battery to hold the wires down. Place a 1" Kapton tape disc at each end of the battery and fold the edges over the side of the battery. Then slide the 1" Heat Shrink Tube over the battery with the tube flush with the positive end of the battery. All the tube slack should be sticking out the negative end. Now use a heat gun to shrink the tube to complete the battery assembly.

Do this again for the second battery.

Step 4: Solar Socket Assembly and Test


Cut the USB cable with the male end 27.9" long. From that piece, cut a segment of wire 2.3" long. Strip .5" of the outer jackets and shielding of both cables and cut away the Green and White wires as they are not needed. Crimp the Hirose Pins on to the 4 wires. Splice the Male cable 2.3" from the end and solder the 2.3" segment of wire in parallel to the male cable with the red wires soldered together and the black wires soldered together. Wrap the wires with electrical tape to create the Y-cable. Connect two Hirose 4-Pin connectors to the wires with the Red Wire pin to port 2 and the Black Wire pin to port 1

Tie a knot in the cable 8.1" from the end to form a strain relief. Wrap the knot with some double back tape and electrical tape to make it bigger if needed.

Cut two Male connectors 8.1" long from a 3' Male-Female cable and the leftover piece of Male Cable from the solar panel. Strip .5" of the outer jacket and shielding of both ends. On both cables, connect the Red Wire pin to port 1, the White Wire pin to port 2, the Green Wire pin to port 3, and the Black Wire pin to port 4.

Solder the .20" stripped end of the short black wire to the short leg of the LED (cathode) and solder the .20" stripped end of the short red wire to the longer leg of the LED (anode). Slide the 1/16" heat shrink tube over the LED legs and use a heat gun to shrink the tube. Crimp the Hirose pin to the ends of the wires. Attach the Hirose 2-Pin connector with the Red Wire to port 2 and the Black Wire to port 1.

Drill a hole above each connector with the 13/64" drill bit and push the LEDs through the holes.


Put a piece of double back tape on two opposite corners inside the electrical box. Feed the Y-cable through the electrical box and place the batteries on the tape so they don't fall. Connects the two short male cables to the faceplate connector.

Attach the two Circuits to the cable connectors as indicated below:

Short Male cables - Connect to ports labeled USBOUT

Y-Cable - Connect to ports labeled IN6V

LED cables - Connect to ports labeled LED

Connect the batteries to the ports labeled BAT last to ensure that nothing shorts.

At this point you can test to make sure that everything is connected properly. Plug the male Y-cable in to any USB port and make sure that the blue LEDs turns on. Now connect your phone to the USB socket with your phone charge cable and both Solar Socket and your phone should charge at the same time. Disconnect and reconnect the Y-cable from the USB port a few times to simulate a shadow on a solar panel and your phone should keep charging, but the Solar Socket LEDs should turn on and off. If it works, continue to the next step.

Carefully push the cables and circuits inside the electrical box and screw the face plate on.

Step 5: Solar Socket Installation

Installing Solar Socket in to your home is a simple 3-step process that takes only a few hours!

First, mount the solar panel anywhere there is sun like on the side of the house or below an eve.

Second, drill a hole for the power cable and insert the 10 foot power cable through the hole.

The solar panel can mount to any side of the house. Find any south-facing area on the home and attach the solar panel there with a few screws. The small, powerful solar panels are lightweight and don’t need to be attached to the roof.

For the last step, cut a hole in the wall for Solar Socket, connect the cable, and mount Solar Socket to the wall. When you screw the electrical box in to the wall, the tiny flaps should engage and push from behind the sheet rock to secure the box. Solar Socket is modular, so if you need more power, just add another Solar Socket! You’ll see that power is generated immediately after installation. Charge your phones, cameras, music players, Bluetooth speakers, GPS devices, and more! When the power grid goes out, Solar Socket still produces energy in an emergency.


Now you have solar power to charge your electronic devices! It’s that easy!

Safety and Troubleshooting on Next Page --->

Step 6: Safety and Troubleshooting


Do Not connect the solar panel directly to a Smart Phone. The solar panel outputs up to 6 Volts of raw unregulated solar power that may not be compatible with Smart Phones. Only connect the solar panel to Solar Socket.

Do Not leave the Solar Socket electrical box in direct sunlight. Keep it covered or in the shade. Heat from the sun can cause the charge circuit and battery to get very hot, stop charging, degrade the battery, and shorten its lifespan.

Acceptable Temperatures: Solar Socket is designed to be operated in temperatures between 0º and 45º C (32º and 149º F).

Keep USB Connectors Dry: If the USB connectors get wet, dry them off. They are water-resistant, but the metal USB connectors may rust with long exposure to moisture. Shake and blow out moisture inside the connector.

Storage: Store the Solderdoodle in room temperature. Solderdoodle should be recharged about once a year to prevent over discharge. For best results, fully charge Solderdoodle before using.


I installed Solar Socket and it didn't charge my phone:
1) Trees, mountains, and buildings may block the sun as it moves through the sky, which dramatically reduces power output. Placement and angle of the solar panel is very important for phone charging. Luckily, smart phone Apps like these can help predict the sun's path using augmented reality through your phone's camera so you can see where the least obstructed position and angle will be throughout the day:




2) While a few clouds or thin hazy clouds will still work for solar charging, thick dense clouds won't. If it's a very cloudy day, Solar Socket may still charge, but wait until there is a break in the clouds to start solar charging your phone.

3) Charging very early in the morning or very late in the afternoon may still charge Solar Socket, but they are the weakest times for solar charging your phone because the sun is very low in the sky and Earth's atmosphere absorbs a lot more light. The sun is strongest in the summer from 8am to 4pm and in the winter from 10am to 2pm. Try charging your phone around these times.

4) If the solar panel surface is very dirty, it can significantly reduce the power output to your phone. Solar Socket may still charge, but try cleaning the solar panel surface before solar charging your phone.

5) Make sure Solar Socket has about 15 minutes of solar charge before plugging your phone in. This will ensure that the battery has enough energy to compensate for brief power fluctuations and keep your phone charging.

Solar Socket LED doesn't light up when solar charging:

1) This can occur if Solar Socket is completely drained and goes in to a trickle charge mode. Solar charge Solar Socket for about 15 minutes and the LED charge light should turn back on.

My phone still isn't charging:

1) Thinner USB charge cables have a history of not lasting very long. Charge cable damage can be visible, but sometimes it is not. Try replacing your phone's charge cable.

2) After a few years of use, the battery inside the phone tends to wear out and perform poorly. If your phone's battery has trouble holding a charge or runs out of power faster than usual, try replacing your phone's battery.

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6 years ago

Once i have all of the parts, how long will this take me to completely set up? (not including step 5: solar socket installation)


7 years ago

This is awesome!
I'm a complete newbie to solar panels and want to build this as my first project. One question regarding the batteries - how safe are these inside the electrical box? Can they get overcharged? could it cause a fire?


7 years ago

Are you selling any of these? I'd love to get one at a resonable price.


7 years ago

Idea is great, but for the peace of mind, I would prefer a more stable choice of battery to be charged by solar, don't want any surprises.


8 years ago on Introduction

I'm interested in making a couple of these and I'm curious about a few things. First is that I want to make these capable of charging any USB device I plug into it be it phone or tablet and my question is this, I have a Samsung Galaxy tab pro 12.2 and it's got a 9500 mAh battery and it's charger says its output is 2 amps do what would I need to change to adapt this system for it to handle the tablet? I recall seeing in your kick starter page that there were 3 planned versions. My other question is where can I get those small circuits you connect everything to in the box?


Reply 8 years ago on Introduction

USB charging is very inefficient so you want at least double the device battery capacity to charge it 100%. That means you need a battery that is 19000mAh to charge the Samsung Galaxy tab pro 12.2 from 0% to 100% reliably. For solar charging, you actually want a little bit more for reserve for power fluctuations.


8 years ago on Step 1

I have fairly extensive experience with various 18650 batteries, and I can say from experience, the Panasonics aren't the best. I'd reccomend either Sony VTC5's or the Purple Efest 35A batteries. You'll get more available power, and they can definitely handle the 2A charging produced by this setup.

(experience: I produce high quality personal vaporizers (ecigs) that use 18650's. Safety is top priority!)


Reply 8 years ago on Introduction

The capacity of those batteries are a little low. USB charging is very inefficient so you need at least 3000mAh to charge an iPhone from 0% to 100%.