What case studies does PV-BESS-Assessor present?

PV-BESS-Assessor documents 20 anonymized case studies from expert assessment practice, including yield assessments, fire cause investigations, thermography (incl. drones), electroluminescence, VdS inspections per clause 3602, DGUV Regulation 3 inspections, grid analyses, lightning protection inspections, valuations, court expert reports, and battery storage safety assessments.

Which standards does the expert assessor apply?

The expert assessor works according to DIN VDE 0100, DIN VDE 0105, DIN EN 62446 (IEC 62446), IEC 61215, IEC 61730, DIN EN 62305 (lightning protection), VdS 2871 / VdS 3602 (fire insurance clause), DGUV Regulation 3, VDE-AR-E 2510-50 (battery storage), DIN EN 50549, DIN EN 50160, DIN EN 13306, and other recognized standards.

For whom does PV-BESS-Assessor prepare expert assessment reports?

Clients include courts, insurance companies, grid operators, investors, project developers, system operators, architects, planning offices, industrial companies, and private individuals. The expert assessment office operates Europe-wide from offices in Munich, Frankfurt am Main, and Stuttgart.

Case Studies — PV & BESS Assessments

Praxisbeispiel

01

Yield Assessment

Yield Loss of a 320 kWp Rooftop System – Root Cause Analysis and Assessment

The operator of a commercial rooftop PV system identified an underperformance of approx. 18% compared to the yield forecast over two years of operation. The insurer commissioned an independent expert assessment.

Result: Through IV curve measurement, thermography, and string analysis, defective bypass diodes, faulty MC4 connectors, and suboptimal string wiring were identified as causes. The yield loss was quantified at 87,400 kWh p.a.

DIN EN 62446 IEC 61215 320 kWp

Praxisbeispiel

02

Fire Cause Investigation

Fire Cause Investigation on a PV System on an Industrial Building

Following a smoldering fire in the junction box area of a PV module, the expert assessor was commissioned by the building insurer for root cause analysis and damage evaluation.

Result: Microscopic examination and arc analysis revealed a serial arc at a poorly crimped cell connection. The damage was documented per VdS 3145 and quantified at EUR 145,000.

VdS 3145 IEC 61730 Arc analysis

Praxisbeispiel

03

Drone-Based IR Thermography

Drone-Based Thermography of a 4.2 MWp Solar Park

As part of a technical due diligence, a full-area IR thermography was conducted using a calibrated thermal imaging camera mounted on a drone.

Result: Of 12,600 modules, 247 showed thermal anomalies (1.96%). Of these, 18 modules with critical hotspots (>30 K overtemperature), 89 with substring failures, and 140 with minor cell anomalies. Claim value: EUR 62,000.

IEC 62446-3 4,2 MWp 12,600 modules

Praxisbeispiel

04

Battery Storage Assessment

Premature Capacity Loss of a 30 kWh Lithium-Ion Storage System

A commercial enterprise reported a capacity loss of 38% after 3 years of operation. The manufacturer denied the defect and attributed it to improper operating conditions.

📚 Scientific basis: Stationary Battery Storage – Market Development and Long-Term Measurements →

→ Study: Changing Battery Chemistries and Critical Minerals

Result: Through capacity testing per VDE-AR-E 2510-50, BMS log data analysis, and cell impedance measurement, a manufacturing defect (inhomogeneous cell chemistry) was verified. Warranty claim confirmed.

VDE-AR-E 2510-50 BMS analysis 30 kWh

Praxisbeispiel

05

Court Reports

Court Expert Report: Defect Assessment of a 98 kWp PV System

The regional court commissioned an expert assessment to evaluate alleged installation defects. The matters in dispute were module mounting, cable routing, and DC disconnect arrangement.

Result: Of 14 reported defects, 9 were classified as standards-relevant (DIN VDE 0100-712), 3 as cosmetic defects, and 2 as unfounded. Defect remediation costs: EUR 34,200 net. Diminished value: 12%.

DIN VDE 0100-712 §404 ZPO 98 kWp

Praxisbeispiel

06

Electroluminescence Examination

Electroluminescence Examination of Defective Solar Modules After Hail Damage

Following severe hail damage, 480 modules were examined using a mobile electroluminescence camera. Objective: differentiation between wear-related degradation and hail-induced cell fractures.

Result: 67 modules with hail-induced cell fractures (star-shaped), 23 with pre-existing micro-cracks, 12 with PID-related degradation. Insurance damage: EUR 89,500.

IEC 60904-13 PID analysis 480 modules

Praxisbeispiel

07

VdS Inspection per Clause 3602

VdS Inspection of Electrical Systems in a Production Hall per SK 3602

Recurring inspection of the entire electrical installation per VdS 3602, including findings report per VdS 2229. Scope: main distribution board, 14 sub-distribution boards, 3 machine groups.

Result: Findings report with 42 defects: 6 Category A (immediate danger), 18 Category B, 18 Category C. Re-measurement after defect remediation with clearance.

VdS 3602 VdS 2229 DIN VDE 0100-600

Praxisbeispiel

08

Valuation / Market Value

Valuation of a 180 kWp PV System in a Property Transaction

Determination of the current market value of the roof-integrated PV system (year of construction 2016, EEG remuneration) for buyers and financiers, including remaining useful life projection.

Result: Income approach considering technical degradation and remaining EEG remuneration period. Market value: EUR 187,000 (book value: EUR 124,000). Remaining useful life: 17 years.

Income approach EEG remuneration 180 kWp

Praxisbeispiel

09

Overvoltage Damage

Overvoltage Damage from Lightning on PV System and Building Installation

An indirect lightning strike caused damage to inverters and building installation. The insurer commissioned a damage assessment of the claimed EUR 78,000.

Result: Evidence through ALDIS data and damage pattern. Missing surge protection Type 2 (SPD) as contributing cause. Settled damage: EUR 52,300 less deduction for betterment.

DIN EN 62305 VDE 0185-305 SPD Typ 2

Praxisbeispiel

10

Self-Consumption Optimization

Self-Consumption Optimization with Storage Integration for Commercial Operation

Economic viability analysis of various storage configurations for an existing 120 kWp PV system at a medium-sized commercial enterprise.

📚 Scientific basis: Battery Revenue Stacking →

→ Study: System Utility of Large-Scale Batteries

Result: 60 kWh storage as optimal sizing. Self-consumption rate increased from 42% to 71%. Payback: 8.4 years. Peak shaving potential: 35 kW.

Load profile analysis Storage simulation 120 kWp / 60 kWh

Praxisbeispiel

11

Shading Assessment

Shading Assessment with 3D Horizon Analysis in Neighborhood Dispute

Following construction of a new building: measurement-based analysis of the shading situation before and after development, commissioned by the court.

Result: Through SunEye horizon analysis and 3D simulation: additional yield loss of 8.2% (1,640 kWh/a). Capitalized diminished value over remaining term: EUR 14,800.

3D simulation SunEye Monitoring data

Praxisbeispiel

12

Storage Safety Assessment

Thermal Runaway – Safety Assessment for Utility-Scale Storage in Commercial Property

Safety assessment of a 200 kWh storage system following a thermal runaway incident in a comparable system. Cell chemistry, BMS, ventilation, and structural fire protection measures were evaluated.

📚 Scientific basis: Thermal Runaway Propagation in BESS →

→ Study: Fire Safety of Li-Ion Batteries

→ Study: Gas Emissions from Li-Ion Thermal Runaway

Result: Deficiencies in exhaust gas routing and missing propagation barriers identified. Action plan with 8 retrofit items. After implementation: re-assessment with positive result.

VDE-AR-E 2510-50 UL 9540A 200 kWh

Praxisbeispiel

13

Grid Analysis & Power Quality (EMC)

Grid Analysis and Voltage Quality Measurement in an Industrial Facility

Recurring machine failures due to suspected harmonic distortion. 7-day grid analysis at the point of common coupling with a 250 kWp PV system.

Result: THD-U of 12.4% (limit DIN EN 50160: 8%). Main causes: 5th, 7th, and 11th harmonic. Recommendation: active harmonic filter. After implementation: THD-U < 4%.

DIN EN 50160 DIN EN 61000-2-2 7-day measurement