Mining is a great way to deal with excess energy from solar farms.

When solar power plants produce more energy than needed, that means we have to shut down some of the plants temporarily. This is costly, and also means we require alternative energy for cloudy and rainy days. Solar still produces energy on these days, but not enough.

If we make more solar plants so we can have enough energy even for cloudy days we instead get too much energy on sunny days, and we are forced to shut down the plants temporarily, and this is essentially wasted money for these electric companies, so why would they want more solar plants?

Producing a lot of plants just to expect them to run with low efficiency and with half of them shut down on sunny days is wasteful and costly.

However, if we instead have mining rigs consume the excess energy, we get a stable energy flow, because mining rigs will turn on and off based on the cost of electricity. Supply and demand stabilize.