I orginally made this list for myself (baby diy developer), as a folder full of bookmarks was becoming unruly. A lot of these links are going to be specific to the US or the Midwest/Great Lakes area, but there should still be plenty of useful stuff no matter where you are in the world. Residential systems aren't really my wheelhouse and I personally am not a fan of batteries, but I've tried to add some good info for those interested.