You talking a shed type deal in the woods? Or house extension, etc... ?
Buy enough solar panels / etc for your constant wattage needs, wire it all together, bingo. Done. Everything from location to size goes into this. Will there be a water source at the grow location, river/well/faucet ?
I always dreamed of having a massive underground grow operation, under a cabin deep in the woods, using alternative energy. Takes a ton of overhead to make things like this kick start in a timely manor. But the pay off would be quite worth it. Within a year depending on going rates you could have the whole set up paid off, if one has the right connections to move some heavy ass weight.