Cheap Solar Panels Find

I went to Target, Mondawmin Mall, this weekend picked up a couple of solar powered garden lights on clearance. I got 2 lights for $12.48 and the box claims that the lights output 19 lumens with a 8-10 hour runtime. There were about 20-25 other sets of these or similar lights as of Saturday. This is how to disassemble them and the parts you will end up with.

Disassembly:

Here is the pre-hacked light.

And the bottom. Notice the 4 screw holes around the outside. Those need to be removed and the light will come apart. No plastic tabs to release.

The light opened. There are 4 wires keeping the whole thing from becoming 2 parts. The black and yellow run to the solar panel and the 2 green wires run to a photocell like this one: Sparkfun Photocell

The photocell can be removed from the top by taking a flat head screwdriver and sliding it under the hot glue glob holding it down. The solar panel will need to be desoldered from the board.

First unscrew the circuit board from the bottom

and then desolder the yellow and black wires connected to the S+ and S- pads. I just pulled on the wire while holding the soldering iron to the solder.

If you now look at the bottom of the top part you will see some rubber glue filling the hole. This needs to be carefully cut around the perimeter with a knife to free the solar panel from the plastic. Don’t cut too deep so you don’t damage the panel.

After you have cut the rubber glue flip the top over and start to pry the solar panel up, starting at the corner and working your way around, careful not to stress the panel too much and crack the glass top. There are 4 double sided foam pieces of tape that need to be released.

To release the circuit board from the bottom just desolder the red lead wire coming from the switch to one battery compartment and the last black wire from from the last battery compartment. You’re all done!

Parts:

1 x Solar Panel: Output of 7v, ~100ma under my bright desk lamp. ~$16 Sparkfun Solar Panel

3 x NI-CD AA 700mAh AA Batteries. ~$3 a piece=$9 Digikey Battery

1 x Photocell ~$1.50 Sparkfun Photocell

1 x Switch ~$1.50 Sparkfun Switch

1 x Bright LED w/ Breakout Board. Takes 3v input. ~$1?

Misc resistors, capacitors, and transistors.

Overall a pretty good deal about $29 worth of hardware for about $6.

UPDATE: Just tried hooking 1 panel up to my arduino outside. In direct sunlight with light cloud cover the panel was supplying 6v and 35mA enough to power my arduino with the digital blink program! Even with 1/4 of the panel covered by my had the arduino still ran.