Also can someone explain why we use solar panels instead of mirrors that heat up water and spin turbines? Almost every other method of producing energy uses that and from my understanding its more efficient and probably cheaper.

This is called concentrated solar power, and there are operating facilities representing less than 2% of total worldwide solar capacity (as of 2017): https://en.m.wikipedia.org/wiki/Concentrated_solar_power

In short, as with most things, the answer to "why don't we do more" is that it's more expensive than the alternatives. Because the "feedstock" (sunlight) is free, efficiency doesn't matter much unless land is expensive. The complexity of these systems is also much greater than PV, leading to higher capital and operating costs.

The promise of concentrated solar is that it can serve as energy storage as well (the hot heat transfer medium can continue to heat water and generate power into the night) meaning it has greater potential for base load power than PV. Plus, I think power towers look damn cool.