Here's what I was thinking, in more detail:
As ground based energy buildings become expensive and slow to build as their level increases, I was wondering if it's better to invest in solar sats together with the equivalent defenses, taking into account that you won't leave res on the planet, of course
I have the following practical case:
After sadbutrue destroyed the solar sats that I used to research graviton, some good 1,700 solar sats remained, that provide something like 20,000 energy. I simply assume they don't exist, and count only on my ground based energy buildings up to now.
From that time onwards, almost everyone who is capable of attacking me has probed the planet, but no attack has taken place up to now, most probably because it is unprofitable to do so. In addition, the planet has a reasonable amount of defenses, I would call "light to moderate", compared to other player's planets I 've seen. It's in no way a heavily defended "turtle" planet.
If I did the same on all my planets, i.e. raise the defenses to match this one and build 1,700 solar sats, it would be a cheap way of forgetting about energy requirements for a long time.
Plus, I would have more available fields for mines.