Green - An environmentalist community

For reference: even though plant photosynthesis is reasonably efficient at producing glucose, if you were to extract and process that glucose into a usable biofuel like ethanol, the usable energy conversion for us is around 1%

Solar energy to glucose energy through photosynthesis is about 10% to 12% (this includes energy lost through light wavelengths that is not compatible with the photosynthesis pathway, similar unusable wavelengths also exist for solar panels). So that amount of solar energy is available to the plant for metabolism. Interestingly enough, if you ate the plant, you also get a similar usable energy of about 1% (of the sun's original energy) so our biofuel conversion processes are on par with biological digestion, and our current solar cells surpass natural solar energy conversion in plants (though that's not a completely fair comparison since we're generating electricity while plants make glucose, which has additional losses in the chemical reactions).