How to Size a Home Battery Backup System: Custom vs. Turnkey Installations

Both are fair questions, and the honest answer to the second one depends entirely on the first. So let’s do this in the right order. First I’ll show you exactly how to size a battery backup system for your house. This is the same load math I’d walk through at your kitchen table. Then I’ll lay out the real tradeoffs between a turnkey system like a FranklinWH or Tesla Powerwall and a custom-built component system. By the end you’ll know roughly what you need and which path fits you.