Depends on which appliances you need to run, and for how long.

A fridge, some lights, phone charging and your internet router can typically be covered by a 10 kWh battery for 12 to 24 hours. Air conditioning, electric cooking or an EV charger during an outage is a different story, and you’ll need considerably more capacity.

Work out your critical loads first, then size the battery and solar system around that. Lenergy can work through this with you based on your actual energy usage.