Battery Storage Calculator — 公式
## How to Size Battery Storage
Battery systems are sized based on energy needs and desired backup duration.
### Formula
**Usable Capacity = Daily kWh * Backup Days**
**Total Capacity = Usable / Depth of Discharge**
Depth of discharge (DoD) limits how much battery capacity you actually use. Most lithium batteries recommend 80-90% DoD to maximize lifespan.
Battery systems are sized based on energy needs and desired backup duration.
### Formula
**Usable Capacity = Daily kWh * Backup Days**
**Total Capacity = Usable / Depth of Discharge**
Depth of discharge (DoD) limits how much battery capacity you actually use. Most lithium batteries recommend 80-90% DoD to maximize lifespan.
计算示例
A home needing 30 kWh/day with 1 day backup at 80% DoD and $500/kWh battery cost.
- Usable capacity: 30 * 1 = 30 kWh
- Total capacity: 30 / 0.80 = 37.5 kWh
- System cost: 37.5 * $500 = $18,750
- Powerwalls needed: ceil(37.5 / 13.5) = 3 units