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Storage efficiency shows how efficiently a battery storage system stores and releases energy — a key factor for profitability and CO₂ performance.
Storage efficiency describes how efficiently a battery storage system stores and releases energy. It indicates the relationship between the energy charged into the system and the energy that can actually be used again — making it a key factor for the economic performance and efficiency of storage systems.
Losses occur during the charging and discharging of a battery storage system — for example due to heat, conversion processes in the inverter, or internal system components such as control units and cooling.
The round-trip efficiency (also called charge/discharge efficiency) indicates what percentage of the stored energy can be used again after a complete charging cycle.
An efficiency of 90% means that 9 kWh are available for use from 10 kWh of charged electricity.
• Evaluation of PV + storage systems in terms of economic performance
• Simulation of self-consumption optimization and savings potential
• Selection of suitable storage technologies (e.g. lithium-ion vs. redox-flow)
• Tendering of balancing services or grid-supportive services
• Long-term energy availability in combination with PV systems
• Round-trip efficiency (%): typically 88–95% for modern lithium-ion batteries
• Partial-load efficiency: efficiency at low discharge rates — relevant for grid-supportive operation
• Annual utilization efficiency: overall efficiency across all charging cycles over a year
• Influencing factors: temperature, aging, charging speed, and system design
• Losses (kWh/year): amount of energy lost due to inefficiencies
Storage efficiency directly affects the economic performance and sustainability of a battery system. High efficiency means lower losses, lower electricity procurement costs, and a better CO₂ balance.
When planning and evaluating energy storage systems, efficiency should always be considered together with capacity, service life, and system integration.
