You don't even need a roof. If you have enough land then a ground mount system is more convenient and easier to maintain.
I think by having a roof GP meant lives in a house instead of an apartment. If you don't have your own roof you probably don't have land either.
alt Hacker News
I think by having a roof GP meant lives in a house instead of an apartment. If you don't have your own roof you probably don't have land either.