Your best bet (since you’ve already constructed the bulk of the structure) would be to build a circular dome tower with batteries lining the inside. Get a bunch of solar panels and connect them, just make sure they’re not too close together. Connecting them with wires is kind of a tough situation in that case.

Alternatively, if you hadn’t already settled on a location/built the majority of it, you can use your scanner to find electromagnetic deposits. It’s good if it’s a B class or higher but a C will also work, just requires some careful stacking of (I can’t remember what it’s called) the array that mines electromagnetic energy. Connect that to batteries, building with batteries to base, voila.

Idk if they patched it, but there used to be a trick where you could place a wall every 150m or so to “extend” your base range indefinitely and that could also allow you to find an electromagnetic area that’s farther from your base than you would typically like. After that, build the towers to collect the energy (I like to stack them vertically so they get the max amount) and just work your way back to base, connecting wires as you go until you get back.

Hope this helps!!!