Battery Storage

What Is Battery Storage?

A battery storage system stores surplus solar electricity generated during the day and releases it in the evening and at night. This significantly increases the self-consumption rate and reduces the need to purchase expensive grid electricity.

Key Specifications

Metric	Typical Value
Usable capacity	5—15 kWh
Charge/discharge power	3—10 kW
System efficiency	85—95%
Cycle life	6,000—10,000 cycles
Warranty	10—15 years
Depth of discharge (DoD)	90—100%

Storage Technologies

The two main battery chemistries for home storage:

• Lithium Iron Phosphate (LiFePO4): Safer, longer-lasting, heavier — currently the standard
• NMC (Nickel Manganese Cobalt): More compact, higher energy density, but fewer cycle life

Economics

Battery storage pays off when the difference between the electricity price and the feed-in tariff exceeds the storage cost per kWh. With electricity prices above 30 cents/kWh and storage costs of approximately 10—15 cents/kWh, this is increasingly the case.

Practical Tip

The optimal storage size is based on evening consumption and typically ranges from 1 to 1.5 kWh per kWp of system capacity. Avoid oversizing — a battery that is too large will not be fully charged in winter and offers a poorer return on investment.