They're mostly about producing leafy greens right now for two reasons: proof of concept and profitability. I look forward to the technology expanding to other plant types: tubers, legumes, and the like.
The efficiency of solar panels is improving but not ideal. The advantage is that the energy can be stored in batteries and the light from specialized LEDs only emit the spectrum of light that is useful to the photosynthesis process without generating excess heat. In a controlled environment you're protected from storms and pests. Using aerosolized nutrient delivery eliminates soil management. A good part of your energy profile is likely going to come from traditional sources but the cost of not having to manage acres of land and ship the final product hundreds of kilometres is a big savings.
An argument from the market: do you realize that current vertical farms should demonstrate crazy margins to justify the move to less profitable crops? According to [1], you can sell a cup of micro greens for $5. You will likely need a few times more space (and likely ten times more time) to grow a single soybean plant. The plant will produce a few soy beans that you can sell for less than a cent. How can this be profitable even in a distant future?
The theoretical maximum efficiency of solar panel is around 30%. So 70% of solar energy is already wasted compared to growing stuff in a field, which means that even if the batteries, transmission lines and LEDs are perfect (they are not), you have to cover three times as much land with solar panels as you would have covered with plants. It also seems that you would prefer growing stuff 24/7, for this one needs to compensate for the time when sun isn't shining, which means 9x land. It seems to me that vertical farming will be even more disastrous for the nature than "traditional" one.
The obvious counter to this is to not use solar panels and LEDs, and just pipe the light with pure optics--mirrors, prisms, light-pipes, etc. Split off the green light for some other use, and direct the rest onto the plants. When the sun isn't shining, feed the optics system with a large, efficient plasma lamp.
Of course, you still need to occupy surface area to collect the free solar light, but you don't need to do it over fertile soil. And you're still going to have efficiency losses, no matter what. The primary benefit of growing indoors is not in the lighting, though. It's in the other factors, like water conservation, pest management, climate control, and pollination control.
Plants aren't using 100% of the suns energy though. They use specific wavelength that the sun output. Do they use more than 30% of the suns available spectrum? I don't know.
Any idea if anyone has experimented with using heliostats and light pipes (fiber optics) to move sunlight from the outside to the inside for growing plants, while eliminating the heat issue - for growing plants?
I know it has been done for lighting a room, as well as for artistic purposes - but I am not sure about whether it has been tried for indoor farming...?
The efficiency of solar panels is improving but not ideal. The advantage is that the energy can be stored in batteries and the light from specialized LEDs only emit the spectrum of light that is useful to the photosynthesis process without generating excess heat. In a controlled environment you're protected from storms and pests. Using aerosolized nutrient delivery eliminates soil management. A good part of your energy profile is likely going to come from traditional sources but the cost of not having to manage acres of land and ship the final product hundreds of kilometres is a big savings.