Finding: System Performance Ratio Below Contractual Target
ACME Solar delivered a fleet Performance Ratio of 74.1% over the evaluation period—5.9 percentage points below the 80.0% IEC target. Four of seven inverters consistently failed contract specifications.
While OEM SCADA recorded 97.8% 24-hour availability, daytime operational availability dropped to 96.2% (below the 97.0% SLA). Inverters registered 77.6 cumulative hours in "Shutdown: on fault" during peak generation windows.
Finding: Behind-the-Meter Double Penalty Explains the 16% Bill Variance
Because ACME Solar operates behind the meter, ungenerated solar energy is automatically replaced by municipal grid draw at peak Time-of-Use rates (R5.10 / kWh average). This translates to R94,264 in period losses and an annualized cash drain of R1,146,878 ($69,264 USD).
02
Performance Ratio Analysis
Reference Yield (Irradiance)
700,074 kWh
Theoretical potential per pyranometer data
Actual Fleet Generation
518,487 kWh
Audited revenue meter production
Performance Ratio Gap
−5.9 pp
74.1% actual vs 80.0% IEC target
Inverter
Telemetry ID
Reference (kWh)
Actual (kWh)
PR (%)
Status
Annualized Impact
INV-1
INV-...54495195
100,010
82,108
82.1%
Compliant
+R 24,100
INV-2
INV-...54495196
100,010
78,407
78.4%
Marginal
−R 18,200
INV-3
INV-...54495190
100,010
61,206
61.2%
Critical
−R 320,400
INV-4
INV-...54495192
100,010
64,806
64.8%
Critical
−R 290,100
INV-5
INV-...54495191
100,010
81,908
81.9%
Compliant
+R 21,800
INV-6
INV-...54495194
100,010
65,306
65.3%
Critical
−R 284,500
INV-7
INV-...54495193
100,014
83,710
83.7%
Optimal
+R 42,300
03
Availability Analysis
Daytime Technical Availability
96.2%
Target: 97.0% (O&M Contract SLA)
Recorded Fault Hours
77.6 hrs
All classified as "Shutdown: on fault"
24-Hour Nominal Uptime
97.8%
High nominal uptime masks daytime solar trips
Why Nominal Availability Misleads Asset Managers
Inverters idling normally at night inflate the 24-hour metric to 97.8%. When evaluated strictly during productive daytime irradiance hours (>50 W/m²), availability falls to 96.2%. The 77.6 fault hours coincided with peak tariff periods, magnifying financial loss.
04
Physics-Based Performance Analysis
Physics Expected Production
905,631 kWh
Irradiance × 2,310 kW × 85% system efficiency
Actual Plant Yield
614,352 kWh
Total revenue meter energy delivered
Midday Clipping & Droop Gap
36.1%
Expected 2,194 kW peak vs 1,402 kW actual
Generation Gap Decomposition291,279 kWh Unharvested (32.2%)
Actual Generated: 614,352 kWh (67.8%)Lost to Hardware Faults: 291,279 kWh (32.2%)
05
Anomaly Detection Analysis (Physical World Model)
Critical State Events
931
Shutdown & Trip Events
Underperformance Anomalies
11,809
>20% Below Expected Manifold
Thermal Warnings
1,798
IGBT Heatsink >75°C
Zero Production Windows
104
Daylight Hours Missed
Asoba's self-supervised Joint-Embedding Predictive Architecture (JEPA) builds a continuous operating manifold for each asset, separating ambient weather effects from internal electrical degradation. The world model proved that 92.6% of lost solar yield was internal hardware underperformance, while cloud cover and weather variation accounted for just 7.4%.
Asset
Anomalies
Primary Signature
Isolated Hardware Culprit
INV-3 (54495190)
2,412
MPPT 2 Voltage Collapse
Blown DC string fuse & open combiner circuit
INV-4 (54495192)
2,218
Midday Thermal Throttling
Clogged heatsink fins & cooling fan assembly 2 stall
An executive committee does not require ambiguous engineering charts; they require a costed business case. Ona translates electrical physics into three capital-gated recovery scenarios (directly modeled on the Sun International Sibaya Casino methodology), enabling asset managers to calibrate maintenance interventions against verified payback schedules:
SCENARIO 1
50% Restoration
R573,439
$34,632 USD / year recovered
Energy: +112,439 kWh recovered
Scope: Inverter 3 (INV-3) triage
Focus: MPPT 2 string fuses & combiner block
PAYBACK: < 30 DAYS
SCENARIO 2
75% Restoration
R860,158
$51,948 USD / year recovered
Energy: +168,658 kWh recovered
Scope: Inverters 3, 4 & 6 sub-array overhaul
Focus: Fan assembly, fuses & ground isolation
PAYBACK: 60 – 90 DAYS
SCENARIO 3 · RECOMMENDED
Full Fleet Overhaul
R1,146,878
$69,264 USD / year recovered
Energy: +224,878 kWh recovered
Scope: Full 7-inverter fleet overhaul
Target: Restore fleet to IEC 0.80 PR spec
PAYBACK: < 4 MONTHS
The 3-Year Commercial Horizon Impact
Leaving this 5.9 pp performance gap uncorrected represents a 3-year cumulative loss of R3,440,634 ($207,792 USD) in permanent grid replacement penalties. Repairing Inverter 3 alone captures over 40% of the site's total financial upside.
07
Corrective Actions: JEPA → OEM Manual RAG
The Autonomous Intelligence Pipeline: Telemetry → Manual RAG → Work Order
Instead of generic advice ("inspect all cables"), Ona's JEPA model pinpoints the exact anomalous latent state, queries our vector database of OEM service manuals, and synthesizes part numbers, torque specifications, and step-by-step diagnostic procedures directly for your field technicians.
Selected scenario: 3 · Full Fleet Overhaul
Section 6 sets the operational policy: 100% of annualised R 1,146,878 leaves no targeted inverter loss. Section 7 only items inverters with explicit OEM manual citations: INV-3 = R 320,400, INV-4 = R 290,100 and INV-6 = R 284,500 (R 895,000 total). The remaining R 251,878 (21.9%) is the INV-2 / marginal / availability tail not covered by the same three part-replacement scopes; need either additional corrective scopes, availability-tariff intervention, or residual operational-loss accounting rather than another generic BOM line.
Selected work-order recovery: R 895,000 (all three cited OEM interventions)
Work Order 01: INV-3 (54495190) — MPPT 2 String Fuse Replacement
Financial Recovery: R320,400 / year · Priority: Immediate (7 Days)
Huawei SUN2000-330KTL-H1 Manual §6.4 · Alarm ID 2001
Identified Fault: DC String Undercurrent / Open Circuit on MPPT 2.
Required Part: 15A 1500V DC gPV Fuse (10×85mm) — Part #PV-15A10F.
Torque Spec: DC terminal disconnect screws: 2.5 N·m.
Estimated Labor: 1.5 technician hours on site.
Technician Action Checklist:
De-energize DC disconnect switch on Inverter 3. Verify zero voltage with 1,500V rated multimeter.
Extract fuse holders for Strings 4 & 5 on MPPT 2; test continuity with digital multimeter.
Replace blown fuse element with certified 15A 1500V gPV element (Part #PV-15A10F).
Retorque combiner terminal screws to exactly 2.5 N·m; re-energize DC switch and confirm string current >8.4A.
Work Order 02: INV-4 (54495192) — Heatsink De-Soiling & Fan Unit 2 Replacement
Financial Recovery: R290,100 / year · Priority: 14 Days
Acceptance Spec: $R_{iso} > 1.0 ext{ M}\Omega$ across all DC conductors to earth.
Estimated Labor: 3.0 technician hours.
Technician Action Checklist:
Disconnect all DC inputs on Inverter 6; apply 1,000V test voltage between positive/negative conductors and station ground.
Isolate fault to String 14 (measured at 32 kΩ); inspect rooftop cable run between Modules 16 and 22 for pinching against sharp purlin edges.
Cut damaged section, crimp new MC4 EVO2 connectors with calibrated ratchet crimper, and seal inside UV-resistant conduit.
Retest to confirm insulation resistance exceeds 10 MΩ before reconnecting to inverter.
08
Methodology & Standards Compliance
IEC 61724-1 Class A Performance Ratio
Performance Ratio is computed per the international standard $PR = Y_f / Y_r$, where $Y_f$ is the specific final energy yield (kWh/kWp) and $Y_r$ is the reference yield calculated by integrating hourly global tilted irradiance (GTI) measured by calibrated on-site reference sensors.
Joint-Embedding World Model (JEPA)
Self-supervised representation learning predicts future latent representations from historical sensor observations across 5-minute intervals. Anomalies are flagged when cosine distance between predicted and actual embeddings exceeds 3.0 standard deviations from normal operational baseline.
