It doesn’t make sense to think of it in terms of how much of the Sun’s energy it uses because solar energy is essentially free and unlimited, it comes from an outside system, we don’t need to mine it or carry it or anything and we can’t ‘waste’ it in the same way we can other fuels. All it tells us is the maximum theoretical limit.
10% more energy from solar means a rooftop array could generate an extra 300-500W which is a genuinely useful amount of energy.