Overview Of Key Figures For Battery Backup Systems

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● Battery technology: Do you prefer inexpensive lead batteries or expensive lithium-ion batteries, which are more efficient?

● Storage capacity or nominal capacity: This is specified by the manufacturer in kilowatt hours (kWh) and should always match the PV power.

● Usable storage capacity: This often differs from the theoretical nominal capacity in practice because the final depth of charge reduces the actual capacity.

● Depth of discharge: To protect the solar battery from damage due to deep discharge, it can only be discharged to a final depth of charge specified by the manufacturer. This affects the actual usable battery capacity.

● Charging cycles: A distinction is made between full cycle (from full charge to maximum depth of discharge) and micro cycle (minor discharge and recharge). The service life of a battery storage unit is largely defined by the number of charge cycles.

● Efficiency: Due to electronic control via inverters and charge controllers, every storage system loses a few percentage points compared to the theoretically achievable performance. Lead-acid batteries have a lower efficiency than lithium-ion batteries (approx. 75 percent vs. approx. 90 percent).

● Cycle life: Regardless of the number of charge cycles, batteries have a limited life expectancy. At the end of the cycle life, the original rated power is reduced to about 80 percent.

● Charging and discharging power of the home battery backup system: This indicates how much power the power storage unit can be charged or discharged with. The greater the charging power, the faster the battery is charged in sunshine. The higher the discharge power, the larger the connected power consumers can be.

Data source: BSLBATT Powerwall Battery