In theory we can get a lot of efficiency by converting wavelengths plants cannot use wavelengths plants can use. However after accounting for all the system losses it is really hard to make up the difference. This assumes too that you use the best available solar panels, which are generally only in labs, real world solar installations are generally less efficient (just the chlorophyll vs solar cell number). Most of the losses in photosynthesis still exist either way as well.

On top of that you need to pay for incredible amounts of solar panels.