I think you're right to be skeptical, but I don't think the entire concept is a hoax. Just its implementation under capitalism.
Solar isn't the only source of power; wind is also a valuable source of energy that could be significantly scaled up. One of the drawbacks of these sources is their intermittency - in order to maintain grid load, they usually need some form of energy storage. Any time the energy is stored and released, there are losses, which increase the cost of the energy.
But vertical farming is a perfect application for intermittent power sources. Plants don't need 100% sunlight all the time, they're used to the sun being interrupted by cloud cover and night-time. Probably half of vertical farm energy usage is for keeping the lights on. A digital system that ensured that plants were getting enough light could coordinate with the management of the power grid so that when energy production was at its peak, it would add more load to the grid, and when it dipped, the lights would dim or go dark. With enough vertical farming infrastructure, you could stabilize an intermittent energy grid and reduce the need for expensive energy storage solutions.
Wind in particular can produce a lot of power, even at night. Plants could use this cheap energy to grow outside of the normal hours of the diurnal cycle and be able to thrive even if the lights go dim for a couple of days.