Solar and Wind over generation regularly produce excess capacity
The very nature of renewable energy resources such as solar and wind generation, is obviously dependent upon the natural resources of wind and sunshine. Although we can be certain that the wind will blow and the sun will shine, we are all familiar with how unpredictable these time are, however we can be pretty certain that they will not coincide with periods of peak demand from the grid.
Over-capacity generation can be taken very cheaply and fed back to the grid during high demand periods.
Where energy from, say, a sunny Bank Holiday weekend or a stormy night coincide with low grid demand is regularly wasted in the grid, this energy can instead be delivered and stored via the grid to Opium Power battery storage plants and be made available when demand increases and the natural resources have relaxed.