Technical Classification
Definition
Empirical operational data analysis of real stationary battery storage installations combined with market development analysis. Provides measured degradation curves, cycle efficiencies and operating profiles — the most valuable data source for practice-oriented performance assessments.
Technical Background
vgbe members (power plant operators) provide operational data from real BESS installations. Measured round-trip efficiencies of 82–89% (vs. manufacturer specifications of 92–95%). Calendar degradation 1.5–2.5% p.a., cyclic degradation dependent on DoD and C-rate. Operating profiles show 250–450 full cycles/year in ancillary services operation.
Risks
Gap between manufacturer promises and real-world operation (efficiency, degradation). Limited sample size — not representative of all manufacturers/chemistries. Operating strategy dominates degradation: aggressive cycling (DoD >90%, 2C) significantly accelerates aging.
Standards & Regulations
IEC 62620 (Performance Requirements), IEC 62933-2-1 (Unit Parameters), VDE-AR-E 2510-50 (Stationary Energy Storage), DIN EN 50549 (Requirements for Generating Plants), VDI 4655 (Reference Load Profiles).
Testing Methods
Long-term monitoring with BMS data logging (SOC, SOH, temperature, cycles). Periodic capacity measurements per IEC 62620. Efficiency measurement in real-world operation. Comparative analysis between manufacturer specifications and measured performance. Degradation model calibration.
Common Deficiencies
Manufacturer specifications for cycle lifetime often determined under ideal conditions (25 degrees C, 0.5C, 80% DoD). Real-world conditions (temperature fluctuations, variable C-rates, full DoD) lead to 20–40% faster degradation. Round-trip efficiency in operation 5–10% below datasheet specifications.
Relevance for Investors, Insurers & Operators
Investors: Realistic yield expectations instead of manufacturer prospectuses. Insurers: Calibration of performance guarantees and warranty claims. Operators: Optimization of operating strategy for maximum lifetime.
Assessment by PV-BESS-Assessor
This vgbe study is particularly valuable due to its combination of market analysis with real operational data. Long-term measurements provide empirical degradation data that is rarely available in the literature.
Impact on Investors
Unique data source for due diligence: Empirical degradation curves enable realistic yield forecasts. Cycle efficiency measurements reveal the gap between manufacturer specifications and real-world operation.
Impact on Assessments
Outstanding relevance: Empirical degradation data as a benchmark for SOH evaluations and remaining useful life prognoses. Real-world cycle efficiency values for performance assessments.
Technical Risks
Limited sample size. Technological advances may render historical data obsolete. Operating strategy significantly influences degradation.
Regulatory Significance
Empirical data strengthens the case for realistic capacity guarantees and warranty requirements in tenders.
Conclusion by PV-BESS-Assessor
PV-BESS-Assessor rates this study as one of the most important references for practical assessment work. Empirical operational data is the gold standard for SOH evaluations.
Last updated: 2026-06-16