Capacity says “how long”. Power says “how much at once”.
Capacity in kWh expresses the amount of stored energy. Power in kW determines how fast the system absorbs or delivers energy.
Illustrative example, not data for a specific product: 10 kWh of available energy theoretically covers a load of 1 kW for 10 hours or 5 kW for 2 hours. In practice, we take losses, reserves and technical limits into account.
A large capacity alone therefore does not guarantee that the battery can handle all appliances at once.
Compare the whole system.
| What we check | Why it matters |
|---|---|
| Usable capacity and power | How much energy and power you actually have available. |
| Compatibility with the inverter and PV system | The devices must work together in the designed configuration. |
| Backup functions | A battery does not automatically mean power during an outage. |
| Expandability | Additional modules can be added only within the system's conditions. |
| Warranty and service | The scope of support matters, not just the number of years in the offer. |
A backup reserve changes everyday use.
Energy kept for an outage is not normally available for evening consumption. In the design, we therefore distinguish storing surpluses from the required backup and take both tasks into account.
We also check the installation location, the manufacturer's conditions, protective devices and operating requirements.
Think about the years ahead too.
An electric vehicle or a heat pump can change consumption. A modular system may allow expansion, but not without limits. We check the options already at the first design.