> What if prices for power go way up during the night
Individual energy providers do not control prices. The market does.
If there is market demand for energy at night, then people will fill in the gap to provide it. Anyone pushing up prices at night will have competition from someone else who will undercut them. They'll be forced to drop prices or lose customers.
Batteries are inefficient, expensive, and do not provide an adequate amount of electricity for most purposes. Consider a UPS, they're about 90% efficient at most, and for all that 10% of wasted energy, you get to power your computer for about 15-60 minutes if the power is lost. The batteries only last a few years.
Also, a bigger argument against solar (at least, photovoltaics) is that they use up rare earth metals, have limited lifetimes (Concentrating solar energy is more promising as a sustainable solution, but requires large infrastructure and the right climate to be cost effective.