I have RGB solar spot lights in my yard that come in a set of 3 parts each, which connect together to form the system.
- Solar Panel rated at 6 V / 4 W output.
- Battery Charge Controller, this one has a 18650 battery pack with 2 batteries wired in parallel for 5000 mAh, it has 8205A and DW01A chips for battery protection. The output from the batteries only turns on when there's no input from the solar panel (great for landscape lights). This does nothing but output DC power to the next piece when there's no solar input.
- Four spotlights chained together, each one a PCB with an unbranded MCU and an antenna to control it with an RF remote, and an RGB led. These only take in DC power and each light handles the color changes on its own.
Each part of the system has a waterproof 2-pin connector, so they can be disconnected and replaced. These need 6 to 8 hours to get enough charge to light them up for a good 6 hours.
There are only two spots in my yard that get sunlight for that long, both are in far away corners of my house. The lights I have there will get enough power to stay on the longest, while the others will last 1 to 2 hours.
As an experiment, I ran a long outdoor-rated wire to where the most sunlight is from a darker area. I wired two solar panels in parallel and connected two of the battery packs to that wire. As expected, it works: both lights get power and charge. The battery pack with an additional 10 ft extension cable is running shorter than the one without. Only connecting one battery pack, as expected, leads to a longer runtime.
With this in mind I'm considering two options:
Get 8 or 12 W panels for each set of lights. This would at least provide more juice so the batteries can charge faster but it wouldn't solve the issue in the areas that get less sunlight would still have some lights on and some off at different times of the day unless I run long extensions for each panel.
Get a 12 V 50 W solar panel which would be placed on the sunny side, then run that wire from the shadier area. This wire would now have 12 V. I can then add an additional waterproof box near each set with a regulator to drop the voltage down to 6 volts and feed the four sets of lights on each side of the yard from one panel. I'm aware I will need a wire that is waterproof and rated for that voltage and wattage and there will be a voltage drop since it's about 90 feet from front to back.
Are either of these ideas good?
I'm a programmer and I do embedded circuits (self-taught) but I've never dealt with solar panels or battery chargers.
I would prefer option #2 using a 12 V 50 W panel but I'm not sure if there are risks I haven't considered.
If it's a 50 W solar panel and the load is only 4 W, will that damage the panel, or will the panel just generate the amount of power that the load draws and the rest will be heat on the panel?
EDIT: Here's a little diagram of what I have vs what I'm thinking of doing I hope this makes sense: