I don't know if its a bug or something not developed yet or if its not intended, but the GUI for the solar panels and the windmills, they don't exist.
Thanks!

(I don't see any errors from TechReborn, so it MIGHT be intentional? Idk? If it is, can it be added :)?

There is no GUI, but what would you want on it? I mean it would just be a power bar or something; doesn't seem terribly useful

Nothing to show there. Everything available on The One Probe tooltip.

It isn't based off light level; it either has view of sun straight above or not. It should have a texture that shows if it's on or not.

Alright, wasn't sure. I was thinking it might have some indicator of what light level it is getting.

Thanks.

If the solar can see the sun the indicator on the sides of the block will light up, yeah. IC2 / Advanced Solars did have GUIs for their solar panels, but the only purpose of them was for charging items, basically a glorified batbox with a sun indicator.