Alternative energy economy runs like communist countries. Politicians believe they are naturally equipped to dictate science. As a result, good scientists are forced out of the fields that politicians target. This leaves the bottom of the barrel in these fields.
As a result, "alternative energy" is a significant farce right now. It has seriously damaged economies of several countries. In California, the more alternative energy is generated, the more the poor are forced to pay in electricity bills. A "glut" in alternative energy is good news to the rich who benefit from it, while it's killer news for the poor.
A simpler solution is to have large-scale "Hydrogen Power Plants" that generate electricity by burning hydrogen. These HPPs would also have facilities to generate hydrogen from excess electricity in the grid - and hydrogen storage capabilities.
Given their hydrogen storage and reserves, they can generate a reliable amount of electricity. This reliable capacity can then be fed into the grid to actually lower electricity costs.