Size a battery bank for solar storage or backup power. Enter daily consumption and autonomy days to get required kWh and Ah.
The average NZ home uses 20–25 kWh/day. For 1 day of full backup with LiFePO4 batteries (80% DoD), you need approximately 25–30 kWh gross capacity. Most residential systems install 10–15 kWh for overnight solar storage, not full backup.
DoD is the percentage of battery capacity you can use before recharging. LiFePO4 batteries can be discharged to 80–90% DoD without damaging cycle life. AGM lead-acid should not exceed 50% DoD or cycle life reduces dramatically.
LiFePO4 is almost always the better choice for home storage: 3,000–6,000 cycle life vs 300–500 for AGM, higher DoD, no maintenance, lighter weight, and faster charge/discharge. The higher upfront cost is typically offset by longer lifespan within 5–7 years.