The cost of solar stabilizes when the cost is determined by the cost of land, energy storage, electric grid and transfer cost and installation and maintenance.

If you get the conversion efficiency to the same level as photosynthesis (30% nominally) the cost of energy could approach the cost of producing biofuels.

Except - lots of current biofuels are thought to be "fossil fuel subsidized" and not that energy positive.

Solar panels also don't wear out soil nutrients, don't need crop rotation, and are probably much less likely to be completely destroyed by weather patterns than the average corn crop grown for biofuels.

The efficiency of photosynthesis is nowhere near 30%. It’s 3% if so.

Even if that number is correct for photosynthesis, there are lots of inefficiencies when it comes to converting the products of photosynthesis (biomass) into usable energy (electricity). Wood pellets burn well, but people forget that wood pellets use energy in their creation (drying) and transport (trucks). There are also a host of evils in terms of habitat destruction and emission of pollutants other than CO2. Solar panels can live quietly and locally, producing electricity directly rather than trying to convert it too and from biomass.

Compared to the rest, which are much more static in terms of cost, energy storage will continue to drop in cost almost as much as solar panels will over the next 10-15 years.