As soon as you realise you can rotate the planet it is quite an easy game. Just put 3 solar panels on one side and keep rotating the planet with the sun. Then put a missile launcher on each of 4 quadrants of the planet. From there, fill everything with weapons as you keep rotating.
There is a bug which makes the missile towers OP - their missiles will loiter at the middle of the planet if they miss (target killed early), giving your planet a charged up defense.