My wheels are turning about the possibilities of a solar powered microgreen grow room. One option is to make it look like an ordinary round agricultural grain bin so no one would take notice.
I recommend using the same growing method as this guy:
https://naturalbuildingblog.com/grow-microgreens-spare-bedroom-make-100000-year/
I estimate approx. 9′ interior diameter is all that’s needed to grow year round greens for one person. That includes enough produce for vegetarians who eat lots of greens.
You could use earthbags, rice hull bags or any number of materials. The small diameter makes it fast, cheap and easy to build. You could build a square sloped roof to facilitate installation of solar. Or use the standard conical grain bin top and put solar panels on a separate array.
No windows are needed, just vents. Windows would weaken the structure. This building would work great if you want to be in stealth mode (keep food production out of sight of hungry masses).
I envision shelving all around the interior except for a work table and entry door.
You could build from scratch or buy a used grain bin and line the interior with rice hull bags, etc. Galvanized exteriors are very durable, and used agricultural buildings are cheap. You’d need to add some framing to hang the shelves.