I've often felt similar frustrations, due to the stock market aspect being pretty much random. What I did was make sure I had a diverse range of power generation and always expect each to be only profitably operational about half the time--and set my energy supply to about half my maximum possible output. Then just check in on it once in awhile to make any tweaks needed--sometimes the prices can stay high (or low) for a long time, while others, they fluctuate high-low-high-low almost constantly.
I also kept at least two engineers researching alternate energy sources that were not affected by the market random craziness. Unfortunately, the alternate sources are all natural sources, which means they're effected by natural random craziness instead of the market! But on the plus side, you do not need to worry about financing and buying operational supplies for them; You only have to worry about natural deficiencies. (I'd post more about that, but I don't want to give away mid-to-late game spoilers..)
Just keep in mind that you do not *always* need to be producing the maximum energy output. In fact, I suspect that it's programmed such that demand *always* outpaces supply. Focus instead on keeping your own output stable, even if it's not enough for demand--the city folks may not be happy without full power, but they'll cope.