You do not need to maintain the energy level to maintain the research level. Build / buy enough solar satellites to do research, then dump them back to market. If you keep them after, they will drive up your points with no real value besides potential debris for an enemy.
I advise doing research from a planet in position 1 vs 9. It takes about 7.5k satellites in position 1, 16k in position 5, and about 22.5k in position 9 based on past experience to reach 300k. Each level of Gravitation technology goes up 300k each time / level. So you can use this above estimates to get an idea how many you will need to get to whatever level you are wishing to get to.