Solar power is highly volatile and can't be stored in large quantities. It's not cheap when it is infinitely expensive at night. A better alternative to fusion would be fission. It works, is stable, and will likely remain far cheaper than fusion even when fusion becomes technically possible.
We don't even have much of a storage problem, fission works and doesn't need energy storage. Our problem is rather that coal power is cheaper than fission. Coal plants are responsible for the majority of anthropogenic CO2.
