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It isn't an analogy. Plants are literal solar systems. The only reasons they can't be plugged into the grid is they deal with energy chemically instead of electrically.

It doesn't require that much imagination to say that solar cells might one day be work in an extremely similar fashion to plants. Not likely, but not an outrageous thought.

Nature has produced a cheaper, more ubiquitous and more self-replicating solar system using efficiencies in the 5% range with a theoretical cap of 11%. That suggests we don't need 25% efficiency to accomplish amazing things. It isn't a critical metric.

I'm fine with your equation of plants with solar power. But it's not cheaper; look at the price of biofuels. Aren't they in fact more expensive than fossil fuels and solar panels?

I think most biofuel is currently more expensive because it is diverting high input monoculture crops that are typically grown for feed like say corn ethanol or soybean oil. I believe ethanol from sugar cane in Brazil was cheap but only because the humans laboring to harvest it and process it were paid very little. But yeah the current choice of using industrially farmed high input crops to source biofuel does make it expensive. I think ultimately heavily refined energy dense fuel does require lots of time or energy input to produce.

The energy that a plant captures doesn't go in to biofuels; it goes into growing the plant. Pushing roots through rock, extracting minerals from the earth or whatever it is plants do. Pushing water from the soil up trunks or through stems.

The biofuel is burning what amounts to the plant's surplus energy that it wasn't using for anything, and recovering some of the energy that went growing the mass of the plant. It isn't comparable.

The point here is plants are covered with tiny green solar panels that are grossly inefficient compared to what humans produce. However, they are beyond cheap to produce (in fact they grow themselves) and suggest that we are not even close to pushing the limits on what we can do with solar energy design wise.

Efficiency of the solar panels really isn't all that important compared to making something with the flexibility and weight of a leaf. Comparing efficiency between solar panels is a waste of time outside the research community; all that matters is total cost to install vs. watts produced.

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