The max theoretical efficiency for photosynthesis is 4.6% for C3 and 6% C4 plants, that is of incoming sunlight.

Cheap solar panels, the type used for example on building roofs have a practical efficiency of around 20%. The most efficient but a lot more efficient are 47% efficient, they are used on for example satellites. The max theoretical efficiency is 86%

So we have already lowe cost solar panels that are over 3x as efficient as the theoretical efficiency for plants. Copying photosynthesis is not a good idea for efficiency because we already have more efficient technology.

Plants have the advantage the grow from seeds and do not need to be made in a factory. They also produce sugar chains that are stable molecules we can extra energy from later. There is no need to copy plants we can just use plants and harvest them as an energy resource.

Energy forestry is something that is done. Humans have done it for centuries by letting trees grow used for firewood.