Quick search shows the reason is nothing to do with your sarcasm.
Its origin is traced back to a 1929 company, Solar Aircraft Company.
I agree with OP that the name, while maybe not deliberately, is really confusing in 2026. I thought that was a wind turbines or a solar panel technology, definitely not gas.
How is this sarcasm? I had almost the exact same thought in earnest: A gas turbine company being called Solar Turbines is quite interesting and unexpected if you're not familiar with that particular corporate history.