Solar-Powered Interior Mailbox Light




Introduction: Solar-Powered Interior Mailbox Light

About: Hi. I never know what to say here. Visit to find out more about me if you feel so inclined, or follow @rtech, @42flows, and @BenOnBeer on Twitter for more of what I do. Thanks!

My wife recently ran over one of our cheap solar lights and demolished it. The electronics were still intact and operable, so I decided to tackle a little project I conjured up a couple of weeks ago.

This project re-uses the electronics from a battery-powered, solar-charged outdoor light and adapts them for installation in a standard US mailbox.

I checked the USPS Mailbox Guidelines before I started and didn't see any regulations against this type of project. Here we go!

Step 1: Gather Some Items

This won't be an exact instruction set - just some things to help you think about what you'll need to complete this type of thing.

  • A working electronics set from a solar outdoor light, including the rechargeable battery
  • A project box to house the electronics and battery
  • A mailbox that you don't mind drilling into
  • Common shop tools and materials:
    • drill & bits
    • soldering iron & solder
    • electrical tape
    • adhesive or mounting tape
    • caulk or silicone sealant
    • hot glue & gun

Step 2: Remove the Electronics

Carefully extract the electronics and solar panel from the assembly. If you can't keep everything intact, ensure you have documented the wiring connections you severed. Electrically-speaking, this system will be re-connected exactly as it was originally. Only this time inside a mailbox.

Step 3: Disconnect the Solar Panel

My intention was to mount the solar panel on the top of the mailbox and have everything else inside. I disconnected the wires from the panel so I could run the connections through a small hole in the top of the mailbox.

Step 4: Install the Electronics in a Project Box

I went looking for a project box in the shop and came across a surface-mount telecom box that happened to be the perfect size for what I was doing. The AA battery fit across perfectly!

Find a way to mount the battery connections to hold the battery in place and drill a hole in the box to place the light in. Arrange the wires as necessary and glue things in place wherever you see fit.

When everything is in order, you might want to test the kit to ensure it's all working (except the solar panel, obviously). When you are satisfied, everything is in place, and the cover is on, it's time to mount everything on the mailbox.

Step 5: Prepare the Mailbox

I picked a spot toward the back of the mailbox to mount the light and drilled a hole to pass the photoresistor and the wires for the solar panel through. The photoresistor at its widest point was 9/32", so that's the size of the hole I drilled in the top of the mailbox.

Step 6: Run the Wires and Reattach the Solar Panel

Pass the photoresistor and the two solar panel wires through the hole and re-solder the connections. I chose to hot-glue the photoresistor back to the window in the center of the panel since that was part of the original design. I didn't see a need to deviate from that - this was a perfect setup in my opinion!

Step 7: Make a Mess With Sealant

At this point if everything still works (please test operation at each step!) you should be ready to mount the solar panel to the top with a silicone-type sealant. I happened to have a tube of silicone-based, clear-when-dry door and window sealant so I just smothered it on all over. I'm a function-over-form sort of guy so as long as it works it's fine with me.

Step 8: Mount the Light Inside the Mailbox

Almost finished. All that's left is to stick your new light box to the ceiling of the mailbox. I used hot glue because I couldn't find any mounting tape.

Reaching in a mailbox with both hands and a hot glue gun is not a good idea. I would recommend mounting the light box with some double-sided foam tape or automotive trim mounting tape.

Step 9: Test the Light and Install the Mailbox

All done!

If everything still works, install the mailbox and enjoy!

This is my first published Instructable and I hope I've been clear enough about the process - let me know if I skipped anything major!

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    6 Discussions


    6 years ago on Introduction

    Goto dollar tree. buy 2 maybe 3 solar lights. your only going to use one circuit and one led but your going to use all 3 panels. unless you live in a location pretty southern your just not going to get enough light at all times of the year. the dollar tree solar lights have some advantages. First they are not encapsulated solar cells. IE they won't turn yellow and opaque on you over time. Second no photo eye. it uses voltage from the panel to determine when to turn on or not. if you get real good light 2 might work. put the led up front facing "INTO" the mail box. epoxy putty it into place.

    Paint the inside of the box white.

    all done. you might not even need to put a hole in it just run it through the opening to the top. I might do an instructable if I get around to it.

    I am glad other people are seeing nice use for these neat little gadgets!


    6 years ago on Introduction

    Great idea. I have a few of those lights around for projects that I got for a buck a piece from the dollar store. Also i get home after dark in the winter and cant see anything in my mail box unless i break out my phone (no street lights even close to my house). This would be very convenient for me. Thanks for the great idea.


    6 years ago on Introduction

    It would be cool to add a switch into the circuit so that the light only comes on when the door is open. That way the light isn't on when you don't need it. I liked this 'ible; its a great idea. I'm only mildly electrically inclined but I might try this when I have some free time.


    Reply 6 years ago on Introduction

    I thought about that too, but it uses a Nickel-Cadmium battery and from my experience it's best to keep a regular charge/discharge cycle on them. If the light is only on about 10 seconds a day, the battery would never discharge and may shorten its useful lifespan. Also, I'm not sure if there's any overcharge protection in the circuit.

    If it used an alkaline battery and no charger, a switched light would probably last for years depending on your environment.



    6 years ago on Introduction

    I like this! But I have a different kind of mailbox with a lifting lid and I am thinking about having the light come on only when the lid is lifted, maybe a microswitch or a tilt switch.... got me thinking!