BUYING GUIDE
Home backup is where people most often buy too small. A portable station that keeps a router and phones alive is very different from a system that runs a furnace blower, fridge and well pump. Here is how to think about the step up.
List the essentials: fridge, router, lights, phone charging, medical equipment, maybe a furnace fan. Note the running watts for each, plus the startup surge for anything with a motor. Surge ratings matter because a fridge or pump can briefly pull two to three times its running watts.
The Ultra X is built for installation rather than carrying. The inverter weighs about 70 lb and each battery about 111 lb. It is rated IP54, uses LFP chemistry, carries a 5-year warranty, and switches over in under 10ms standalone (under 20ms with the Smart Home Panel 3). Three inverters can run in parallel for up to 36kW.
Capacity only helps if you can refill it. The Ultra X accepts up to 10kW of solar input across two ports, which is how people stretch a multi-day outage. Smaller stations need panels sized to their own solar input limit, so check that number before buying panels.
Whole-home systems connect to your electrical panel, so have a licensed electrician handle the wiring and check local permit rules. Portable stations need none of this, which is a real advantage if you only need a few circuits.