There are interesting people on thebackshed.net who have been building whole house inverters, initially repurposing some Chinese inverter chip but more recently

There are interesting people on thebackshed.net who have been building whole house inverters, initially repurposing some Chinese inverter chip but more recently an arduino for the brains. Unfortunately a lot of the info is spread across many different build threads but a big part of it is about rewinding toroidal transformers.