you can power your entire map with solar power easily

check out this map. i can easily power an entire industrial base with solar + batteries.

and this isn't an "easy" (beginner) level either. This is Overgrowth (enemy base, threat level: high). I'm 12 waves in and fine.

close-up of the map to the right side of the core:

close-up of the map to the left side of the core:

as you can see in the minimap, most of the map is still empty. so i could easily build much more. but it's not needed. the idea that "solar power generates little energy" (only 7 power / tile under full sunlight) is not actually hindering you from using it in mass-scale. Because basically any map has a lot of unused free space anyways.