I had some small, untabbed solar panels (19*52mm, 0.15W -> max 0.3A @ 0.5V).
I did not know what to do with them until I heard about the touchdown of the japanese Hayabusa 2 Probe. In this instructable I will try to create a model that resembles the Hayabusa 2 Probe - or at least looks a bit like a satellite from space.
Note: if you want to make one for yourself and plan on modifying it, you will probably need to adjust your solar panels and battery capacity. So far I built just the base power system (solar panels, charging ciruit and battery) and no load attached. If you scale this project up a bit you will easily be able to power an arduino, esp8266/32 or something similar.
Step 1: Step 1: Materials and Tools
12*Solar cells: aliexpress
solar panel tabbing wire: aliexpress
1*Charging and protection Cicuit: aliexpress
1*Battery: any small 1S lipo works (depending on power requirements). mine had 600mAh
Battery connectors (depends on the battery you use)
2*LEDs (1 green, 1 red)
case: any project box will do, i got a fancy extruded aluminium case: aliexpress
Soldering iron (flat and normal tip preferred)
electrical / kapton tape
hot glue gun and glue
Step 2: Step 2: Tabbing Solar Panels
first: work clean and do not touch the front of the solar panels without gloves if you care about efficiency.
You will probably break some panels (i did as well). I used some tissue paper to avoid scratches on the panels
We will solder all panels in series to get a voltage of about 5-6V, the charging circuit should be fine with this. 12*0.15W gives us about 1.8W (peak performance). but keep in mind that this project will be installed inside (no garanteed direct sunshine) and will have to work 24h a day (depending on your modifications). With the battery as a energy buffer we will end up with 0.1-0.5W to play with.
Cut the tabbing wires to about 1 1/2 the lenght of your solar panels.
use your flat soldering iron tip. I use a TS-100 with this tip (TS-C4).
clean the tabbing area of the solar panel (white line) with a flux pen. The top of the panel is negative and the bottom positive. I soldered the bottom of each cell first. The tabbing wire should be mostly on the first panel.
now that you have soldered a tab to each cell you can link them up in series. space them evenly and solder each underside to the upperside of the panel next to it.
Step 3: Step 3: Prepare Charging Circuit
change the tip of your iron back to a normal pointy tip.
solder on the battery connector. plug in the battery and then connnect it to an USB power source.
the red light means it is charging, blue means charging completed.
I wanted the LEDs to be visible on the outside, so I replaced the SMD LEDs on the PCB with some THT components. I measured the polarity with a multimeter but you can also look closely at the SMD LEDs to determine their polarity. The negative side should have a green marker on it. Use heatshrink tubes to insulate the leads of the THT LEDs and make sure you get their polarity right (shorter lead is negative). The solder connection will not be strong, to help with that i bent little feet on the THT LED leads.
Step 4: Step 4: Reinforce and Mount Solar Panels
Hot glue some popsicle sticks to the back of each panel array to reinforce the fragile panels. if you have a coating film or spray (needs to be transparent on visible and near visible spectrum) apply it now.
Use some tape (i used kapton but regular electric tape works fine) to avoid shorts on the backside of the solar panels. Bend the tabbing wire of the cells and solder some wire to it. Make sure to keep in mind the polarity.
I used some barbeque skewers and hot glue again to mount the panels to the back side of the case. Inside the case i connected the positive lead of one side to the negative of the other side. The two available leads were connected to the IN on the charge circuit. make sure to guide the wires through the screw holes of the case lids (2 out of 4 screws are enough to close it up in the end).
Shove the charging controller inside the case (I drilled some holes into the case for the LEDs).
Step 5: Step 5: Mounting
close up the lids and you are almost done.
use another popsicle stick or any other small piece of wood or plastic to create a mounting point. i just drilled a hole in a small piece of popsicle stick and hot glued it to the back side. use a small nail or needle to mount it in a sunny place inside your home.
ask me if you need any help!
I look forward to see similar projects, maybe with a bit more functionality ;)