Using small solar panels together, worth it?

Question

I am messing around with some solar landscape lights to improve their capabilities. I have gutted their internal workings and replaced them with small neopixel light boards and connected them all back to a controller that runs them all individually. The system being run off an Arduino Mega connected to a Raspberry Pi and 6v/20aH SLA battery.

Each of the landscape lights has an embedded solar panel that puts out about 2.4v/45mA in bright sun. Considering that there are about 35 lights altogether, it seemed like a good amount of power that was being wasted that could be being used in the recharge period. I was curious if it's worth anything to connect the panels back to some kind of regulator circuit and use it to supplement the battery recharging.

I don't have a lot of design experience with solar panels or the finer points of battery recharging, so I was hoping to get a little guidance on a suggested approach. Things like: Is it better to wire the panels in series or parallel? Or would I need some sort of regulator circuit. Or is it even worth bothering with at all? Anyone have any thoughts?

Jerry

Answer 1

If you need more current, then wire them in parallel (which will give you double the current of one cell). Putting two in series will give you double the voltage of one cell.

A regulator can be used, but the problem with this approach is it will not run the solar cells at greatest efficiency. To run the cells at greatest efficiency an MPPT tracking circuit will be needed.

One thing that might work is a buck DC DC converter.

If you're charging a battery, then a controller to monitor the charging will also be needed. Here are a few examples, make sure you match the input cell current and voltage within the chargers range.