How Many Batteries to Power a House: The Complete Sizing Guide
A customer called me last winter, frustrated. He had bought four 12V 100Ah deep-cycle lead-acid batteries, wired them for 48V, and connected them to a 5,000W inverter. His plan: power the furnace, fridge, lights, and router through a 2-day outage. The math on paper said he had 4.8 kWh of usable capacity, and his daily critical load was around 4.5 kWh. He should have had just enough to scrape through 24 hours.