A little caution about low-cost solar panels - check those connections before you lug it onto your roof!

Our outside floodlights have a 150W solar panel feeding a 20A PWM charge controller and about 30Ah of 12V LiFePO4 batteries (batteries are made up of a motley selection of 32650 cells acquired over the years).

I noted from day 1 that the charge current wasn't quite what I expected, but it was filling the batteries so I put it down to the el-cheapo PWM charge controller.

Fast forward a few months and I see the lights are not making it through the night and the batteries are nowhere near full at the end of even a nice sunny day.

Changed the charge controller - no difference. 

Tracing the wiring back to the panel revealed:-

Evidently warmth had been generated over a period, that wire was hanging on by a couple of strands.

The screw terminal was decidedly not tight!

Since the plastic cover was melted and brittle a new one was fabricated, that's just a regular plastic electrical box that was in-stock, not even new. It looked a bit manky so I sprayed it with black acrylic.

Connections were tidied up and proper crimps used on the cables.

Under test before I install it back onto the patio roof.

So, it wouldn't hurt to verify your panel connections are good before hauling them up onto the roof.