Engineering Quality Assurance Methods

I would like to introduce some useful things for solar panel Testing: ⚡ Solar Panel Testing: What We Check Before Procurement & Installation Before any solar panel hits the field, rigorous testing is essential. Here's a detailed breakdown of the key tests and standards we perform to ensure top-tier quality, performance, and long-term reliability. ✅ 1. Flash Test (I-V Curve under STC) 📌 Purpose: Measures actual electrical performance under Standard Test Conditions (STC) 📊 STC Parameters: 1000 W/m² irradiance 25°C cell temperature Air Mass 1.5 🔍 Key Checks: Pmax (Maximum Power): Must be within ±3% of rated capacity Voc (Open Circuit Voltage) & Isc (Short Circuit Current): Should show tight consistency between modules 💡 Why it matters: Verifies that real output matches the manufacturer’s datasheet—no surprises after installation. ✅ 2. NOCT – Nominal Operating Cell Temperature 📌 Purpose: Predicts real-world performance under actual outdoor conditions 📊 Typical Conditions: 800 W/m² irradiance 20°C ambient temp 1 m/s wind speed 🎯 Ideal Range: 42°C – 48°C 💡 Why it matters: Lower NOCT = less heat = better energy yield in the field. ✅ 3. Electroluminescence (EL) Imaging 📌 Purpose: Reveals hidden cell-level defects 🔬 Method: Apply low voltage in darkness to produce infrared emission 🔍 Detects: Microcracks Broken cells Soldering faults 💡 Why it matters: Early detection prevents hotspots, power loss, and premature failure. ✅ 4. Insulation Resistance & High-Voltage Withstand Test 📌 Purpose: Ensures electrical safety and system durability 📊 Test Voltage: 1000–1500V DC, depending on system design 🎯 Minimum Resistance: >40 MΩ at 1000V (per IEC 61730) 💡 Why it matters: Critical for shock prevention, fire safety, and long-term reliability. ✅ 5. PID (Potential Induced Degradation) Test 📌 Purpose: Assesses vulnerability to voltage-induced performance loss 📊 Test Conditions: ~85°C 85% RH -1000V applied for 96–168 hours 🎯 Degradation Threshold: <5% power loss 💡 Why it matters: Vital for high-voltage and humid-climate installations. ✅ 6. QAP (Quality Assurance Plan) Review 📌 Purpose: Evaluates the manufacturer’s internal QA processes 📝 What We Verify: ISO Certifications (e.g., ISO 9001) Recent factory audits Random sampling results (IEC 61215 / 61730) Raw material traceability 💡 Why it matters: Adds confidence beyond lab tests—ensures production consistency and traceability. ✅ 7. Thermal Cycling & Damp Heat Test 📌 Standard: IEC 61215 📊 Test Parameters: Thermal Cycling: 200 cycles from -40°C to +85°C Damp Heat: 1000 hours at 85°C / 85% RH 🎯 Acceptable Loss: <5% degradation 💡 Why it matters: Demonstrates durability in extreme environments (deserts, tropics, snow zones). ✅ 8. Visual Inspection 📌 What We Check: Glass cracks Delamination Frame warping Junction box damage Edge sealing & backsheet integrity 💡 Why it matters: Catching cosmetic or structural issues early prevents installation delays and long-term performance risks.

☠️ A SILENT SOLAR PV KILLER LURKING UNDETECTED ☠️ 🚧 Bypass diodes are critical safety components in every PV module, protecting cells under partial shading and preventing reverse‑bias heating. But growing field evidence reveals a more dangerous issue: Lost Bypass Diodes (LBPD) in open‑circuit, which remain invisible during standard inspections. 📉 Industry reports now show rising contact failures inside junction boxes - unconnected or poorly welded diode terminals - increasingly common in modern module architectures. These faults stem from incomplete or failed solder joints in highly automated production lines, even those with AI inspection. Electrical contacts may appear intact during QC, so modules pass flash testing with no anomaly. With global demand surging and prices squeezed, manufacturers are optimising heavily, yet this defect continues to escape factory controls. 🔎 Open‑circuit LBPD faults are particularly problematic. Unlike short‑circuit diode failures - detectable via thermal anomalies or drone‑based IR - open‑circuit failures produce no thermal signature, no I‑V deviation, and no shading response during commissioning. As recent IR inspection findings show, LBPD cannot be detected by traditional measurements, allowing faulty modules into long‑term operation unnoticed. 🔥 But once shading occurs later in the module’s life, the protected substring is no longer bypassed. Reverse current is forced through shaded cells, rapidly pushing temperatures above 75°C and creating a serious fire risk - a failure mode documented in real‑world case studies, and extremely dangerous on rooftop installations. ✅ Research also confirms that bypass diode failures are among the hardest PV anomalies to detect, with open‑circuit cases often mimicking normal irradiance changes. Advanced modelling shows that distinguishing these patterns requires high‑resolution feature extraction and data‑driven methods absent in standard field tests. 🆕 At 2DegreesKelvin, we’re addressing this gap. Our engineering team is developing a new field‑testing methodology to detect open‑circuit LBPD faults, even in modules that pass EL, IR, and flash tests. By analysing subtle electrical characteristics under controlled conditions, our method aims to identify LBPD issues before shading turns them into thermal hazards - a critical step from an insurance perspective. 🌞 If your asset portfolio includes utility‑scale PV or you're seeing unexplained string behaviours, we’re partnering with developers and asset owners to validate this diagnostic approach. Trials are underway, with a scalable service planned soon. DM me or email: info@2degreeskelvin.org for early‑stage field trial collaboration. Image credit to: Erik Lohse - Thank you Erik 😊 #makesolarbetter

Early in my career, I believed progress came from intensity. Long nights. Big pushes. Short bursts of extreme effort. It works for a while. But tech careers are not marathons. They’re not sprints either (pun intended!). They’re long hikes. Over more than two decades in this industry, what I’ve seen consistently outperform raw intensity is consistency. Small, repeatable learning habits. Steady exposure to new ideas. Regular practice and showing up… even when motivation is low, even when progress feels invisible, even when it may not be exciting anymore. Intensity feels productive because it’s visible. Consistency is quieter. Harder to notice day to day. But it compounds. Most people don’t burn out because they lack talent. They burn out because their pace isn’t sustainable. If you want to still enjoy this industry 10, 20, 30 years in, design habits you can maintain on a bad week, not just a good one. That’s how real careers are built. If you’re building a long-term career in tech, consistency will beat intensity every time. #careerintech #softwareengineering #techcareers #learning

If you're a software engineer working with AI in your workflow, here's a simple prompt to make sure you're 100% covered from a security point of view, based on my last 6 years in DevSecOps: Paste this into your agent before you ship anything important: You are a senior security engineer performing an adversarial security audit of this codebase, app, or system design. Assume it will run in a hostile environment with motivated attackers. Audit these layers: - frontend - backend - auth and permissions - database and storage - infrastructure and deployment - third-party integrations and dependencies Your job: 1. Find critical, high, medium, and low severity issues 2. Catch logic flaws, not just common patterns 3. Identify multi-step attack paths 4. Flag unusual or non-obvious risks 5. Think like a creative attacker, not a checklist scanner Threat model first: - define attacker types - identify entry points - identify trust boundaries - identify sensitive assets like data, secrets, tokens, and permissions Check for issues in: - auth, sessions, password reset, token misuse - broken authorization, IDOR, privilege escalation - SQL, NoSQL, command, template, and file upload attacks - XSS, CSRF, replay, race conditions, cache poisoning - mass assignment, rate limit gaps, brute force paths - secret leaks, weak crypto, insecure storage, bad logging - CORS, CSP, headers, debug endpoints, env leaks - cloud or deployment misconfigurations - vulnerable or risky dependencies Also try to discover: - feature abuse - impossible-but-possible behavior - state desync issues - weak trust assumptions - attack chains built from smaller issues Output format: 1. Vulnerability summary by severity 2. Detailed findings with: - title - severity - affected component - description - exploitation steps - impact - recommended fix 3. Attack chains 4. Secure design improvements Important: - assume nothing is safe - infer risk where context is missing - be exhaustive - if something looks risky but uncertain, flag it and explain why Most people use AI to write code faster. Very few use it to pressure test what they just built. That second use case will save you a lot more pain. -- 📢 Follow saed if you enjoyed this post 🔖 Be sure to subscribe to the newsletter: https://lnkd.in/eD7hgbnk 📹 Reach me on https://lnkd.in/eZ9mU5Ka for open DM's

Don’t Focus Too Much On Writing More Tests Too Soon 📌 Prioritize Quality over Quantity - Make sure the tests you have (and this can even be just a single test) are useful, well-written and trustworthy. Make them part of your build pipeline. Make sure you know who needs to act when the test(s) should fail. Make sure you know who should write the next test. 📌 Test Coverage Analysis: Regularly assess the coverage of your tests to ensure they adequately exercise all parts of the codebase. Tools like code coverage analysis can help identify areas where additional testing is needed. 📌 Code Reviews for Tests: Just like code changes, tests should undergo thorough code reviews to ensure their quality and effectiveness. This helps catch any issues or oversights in the testing logic before they are integrated into the codebase. 📌 Parameterized and Data-Driven Tests: Incorporate parameterized and data-driven testing techniques to increase the versatility and comprehensiveness of your tests. This allows you to test a wider range of scenarios with minimal additional effort. 📌 Test Stability Monitoring: Monitor the stability of your tests over time to detect any flakiness or reliability issues. Continuous monitoring can help identify and address any recurring problems, ensuring the ongoing trustworthiness of your test suite. 📌 Test Environment Isolation: Ensure that tests are run in isolated environments to minimize interference from external factors. This helps maintain consistency and reliability in test results, regardless of changes in the development or deployment environment. 📌 Test Result Reporting: Implement robust reporting mechanisms for test results, including detailed logs and notifications. This enables quick identification and resolution of any failures, improving the responsiveness and reliability of the testing process. 📌 Regression Testing: Integrate regression testing into your workflow to detect unintended side effects of code changes. Automated regression tests help ensure that existing functionality remains intact as the codebase evolves, enhancing overall trust in the system. 📌 Periodic Review and Refinement: Regularly review and refine your testing strategy based on feedback and lessons learned from previous testing cycles. This iterative approach helps continually improve the effectiveness and trustworthiness of your testing process.

⚡ 500 kV Current Transformer (CT) Testing & Diagnostic Analysis: Recently, I performed complete diagnostic testing on a 500 kV Current Transformer (CT) to evaluate its accuracy, insulation integrity, and overall performance. CTs play a critical role in protection and metering circuits — ensuring their health is essential for safe and reliable operation of high-voltage systems. 🧪 🧰 Tests Performed & Objectives 🔹 1. Insulation Resistance (IR) Test Purpose: Assess insulation health between primary, secondary, and core. Method: High-voltage DC applied using a Megger Insulation Tester. Interpretation: High IR → Healthy insulation Low IR → Possible moisture or insulation deterioration 🔹 2. CT Analyzer Testing (Megger CT Analyzer) Comprehensive testing performed using Megger CT Analyzer, which automatically measures and analyzes all electrical characteristics of the CT, including: ⚙️ Winding Resistance (WR): Evaluates resistance of secondary windings to detect loose connections or shorted turns. (Measured automatically by CT Analyzer with temperature correction applied.) ⚙️ Ratio Test: Confirms the actual turns ratio matches the nameplate ratio. ⚙️ Phase Error / Phase Displacement: Measures angular deviation between primary and secondary currents — essential for accurate metering and protection. ⚙️ Excitation (Magnetization / Saturation) Curve: Determines the knee-point voltage and CT core behavior under fault conditions. ⚙️ Burden & Accuracy Class Verification: Confirms the CT maintains accuracy under rated burden as per IEC / IEEE standards. ⚙️ Polarity Test: Verifies the correct orientation between primary and secondary terminals. ⚙️ Demagnetization Function: Automatically demagnetizes the CT core after testing to restore accurate characteristics. 🔹 3. Capacitance & Dissipation Factor (C&DF / Tan Delta) Test Purpose: Evaluate insulation dielectric condition and detect early aging. Method: High-voltage AC applied; Capacitance and Tan Delta (Dissipation Factor) measured. Interpretation: ⭐ Stable capacitance → Healthy insulation ⭐ Increased Tan Delta → Possible moisture, heat, or contamination #CurrentTransformer #CTTesting #CTAnalyzer #ElectricalEngineering #PowerEngineering #TanDelta #CapacitanceTesting #DissipationFactor #WindingResistance #InsulationResistance #Megger #HighVoltageTesting #ConditionMonitoring #AGITROLSolutions #Siemens #TestingAndCommissioning #ProtectionSystem #ElectricalTesting #IEEEStandards #IECStandards

The guilty pleasure when Doing R&D as a Robotics Engineer Before diving into more "production-ready" solutions, I think it's the right approach to start by testing the concept - something quick to build that lets you validate your idea fast. With tape - yes, tape - is exactly how we first mounted our camera, for example. It wasn't perfect, but it allowed us to confirm the placement worked. Same goes for all our sensors. Our core principle is simple: we apply the fail fast mindset even within the R&D team. We take as many shortcuts as we can to validate ideas quickly. Only once something is validated do we decide how to make it more robust and production-ready. The fail fast concept isn't just a business buzzword ; it absolutely applies to your R&D team too. Here, it's mechanical engineering, but the same logic works across every domain.

What if the best solutions for your process started with cardboard? When testing new ideas or improvements, jumping straight to high-cost, permanent solutions can be risky—and expensive. That’s where cardboard engineering comes in. Cardboard is one of the simplest, most cost-effective tools for rapid prototyping and testing ideas. It’s lightweight, easy to shape, and lets you visualize, test, and refine your concepts before committing to more expensive materials. Why Cardboard Is Perfect for Prototyping: 1️⃣ Low-Cost Experimentation Testing with cardboard lets you try multiple iterations of a design without worrying about material costs. 2️⃣ Fast Feedback Loops You can build and modify a prototype in minutes, gathering instant feedback from your team or operators. 3️⃣ Hands-On Collaboration Cardboard prototypes allow teams to actively engage with ideas, making it easier to identify issues or opportunities for improvement. 4️⃣ Visual Validation Sometimes, seeing a physical model highlights challenges that wouldn’t be obvious in a drawing or plan. How to Use Cardboard for Lean Improvements: 🔍 Test Workstation Layouts Use cardboard cutouts to mock up layouts and placement of tools, parts, and equipment. Adjust until everything flows smoothly. 📦 Simulate Material Flow Prototype racks, bins, or carts to ensure materials are stored and moved efficiently before building them with more durable materials. 🛠️ Design Fixtures or Jigs Create cardboard versions of fixtures or jigs to test their functionality in the process. Refine the design before investing in the final version. 📐 Test Ergonomics Mock up equipment or workstation designs with cardboard to test ease of use, reach, and operator comfort. Example of Cardboard in Action: A manufacturing team wanted to redesign a workstation to reduce operator motion. Instead of committing to expensive reconfigurations, they used cardboard to prototype the layout. After several iterations, they found the optimal setup, reducing motion by 25% and saving hours of work. Cardboard isn’t just for packaging—it’s a powerful tool for testing and refining your ideas. By prototyping with low-cost materials, you can experiment, learn, and improve quickly without breaking the bank.

What is RTM and How is Used by Business Analysts? RTM (Requirements Traceability Matrix) is a document that tracks and ensures that all project requirements are properly addressed throughout the project lifecycle. It links requirements to their corresponding test cases, design documents, and deliverables, ensuring complete coverage and reducing the risk of missing critical functionalities. How Business Analysts Use RTM: 1. Tracking Requirements – Ensures all business, functional, and technical requirements are addressed. 2. Validation & Verification – Helps confirm that each requirement is implemented and tested. 3. Change Management – Assists in assessing the impact of changes on existing requirements. 4. Project Transparency – Provides clear visibility to stakeholders on requirement progress and gaps. RTM is crucial in bridging the gap between business needs and project execution, making it a key tool for Business Analysts. #rtm #requirementtraceabilitymatrix #businessanalyst #Bas

Solar Module Reliability Tests These are a critical part of ensuring photovoltaic (PV) modules perform safely and efficiently throughout their expected lifespan (typically 25–30 years). These tests are defined by international standards such as IEC 61215, IEC 61730, and UL 1703, and are typically conducted in certified laboratories. 🔧 1. Thermal Cycling Test (IEC 61215) Purpose: Simulates stress from daily temperature changes. Conditions: -40°C to +85°C for 200–600 cycles. Failure Criteria: Cracked cells, delamination, or power degradation beyond specified limit. 💧 2. Damp Heat Test (IEC 61215) Purpose: Simulates long-term exposure to high humidity and heat. Conditions: 85°C, 85% RH (Relative Humidity) for 1000 hours. Failure Criteria: Moisture ingress, delamination 🧊 3. Humidity-Freeze Test Purpose: Simulates moisture ingress. Conditions: Cycles of 85°C/85% RH to -40°C. Used to detect: Encapsulant failures ☀️ 4. UV Preconditioning Test Purpose: Exposes modules to UV radiation equivalent to sunlight exposure over time. Conditions: 15 kWh/m² at 60°C. Checks for: Discoloration, encapsulant degradation ⚡ 5. Insulation Resistance & Dielectric Voltage Withstand Test (IEC 61730) Purpose: Ensures electrical safety under wet or humid conditions. Conditions: High-voltage testing of insulation layers. 🌧️ 6. Hot Spot Endurance Test Purpose: Simulates shading or cell mismatch causing local heating (hot spots). Outcome: Identifies risk of fire or localized damage. 🧪 7. Potential Induced Degradation (PID) Test Purpose: Tests susceptibility to voltage-induced degradation. Conditions: High system voltage 1Kv Important for: Utility-scale PV plants. 🌪️ 8. Mechanical Load Test Purpose: Simulates wind and snow loading. Conditions: Typically 5400 Pa (snow) and 2400 Pa (wind). Assesses: Frame integrity, glass cracking, and mounting strength. 🔍 9. Electroluminescence (EL) Imaging Not a standard test, but widely used. Purpose: Detects microcracks, broken cells, or interconnect issues. Used: Before and after mechanical/thermal tests for failure analysis. 🔄 10. Light-Induced Degradation (LID) Test Purpose: Evaluates performance drop after initial sunlight exposure. Mainly affects: Mono PERC and other high-efficiency Si modules. 📉 11. Power Output (Flash Test) Purpose: Measures module output under Standard Test Conditions (STC). Criteria: Power degradation should not exceed 5% (usually tighter in warranties. Test Purpose Standard Thermal Cycling Temperature fluctuation resistance IEC 61215 Damp Heat Humidity and heat endurance IEC 61215 Humidity-Freeze Cold and moisture stress IEC 61215 UV Exposure UV resistance IEC 61215 Insulation Resistance Electrical safety IEC 61730 Hot Spot Test Local heating from shading IEC 61215 PID Test Voltage stress tolerance IEC 62804 Mechanical Load Wind/snow impact IEC 61215 Electroluminescence Imaging Microcrack detection Non-standard tool Flash Test Output performance IEC 61215