Potential Induced Degradation (PID) of photovoltaic modules is a core factor leading to reduced power generation and shortened service life of PV power stations, serving as a key test item for PV module R&D, mass production inspection, outdoor reliability verification, and power station operation evaluation. The high‑voltage power supply is the core power unit of PID test systems, providing long‑term stable high‑voltage bias output to simulate system high‑voltage stress on modules during field operation and accelerate PID degradation. Its long‑term output stability, environmental adaptability, continuous operational reliability, and high‑voltage insulation performance directly determine the accuracy, repeatability, and safety of PID test results. Current mainstream PID standards require the power supply to deliver continuously adjustable DC −1500V~+1500V, operate continuously for 96 to over 1000 hours under 85℃/85% RH high temperature and high humidity, maintain long‑term voltage stability better than ±0.5%/1000h, and support micro leakage current monitoring, arc detection, and full‑condition protection. Traditional high‑voltage power supplies suffer from poor long‑term stability, degraded insulation under high temperature and humidity, weak anti‑interference capability, and inability to support ultra‑long uninterrupted testing, failing strict requirements of IEC 62804, GB/T 37409 and other PID standards. The design fully complies with IEC 62804‑1 *Potential Induced Degradation Test for PV Modules – Part 1: Crystalline Silicon Modules*, GB/T 37409 *Test Methods for Potential Induced Degradation of PV Modules*, IEC 61215 *Design Qualification and Type Approval of Terrestrial Crystalline Silicon PV Modules*, while meeting demands for long continuous operation, multi‑environment adaptability, high‑precision monitoring, and automatic testing. Targeting key application requirements and technical challenges, this methodology establishes a full‑process general framework covering long‑term stable output topology, full temperature/humidity environmental optimization, long‑term reliability design, high‑precision leakage current detection, PV test scenario adaptation, and comprehensive safety protection. It supports PID testing, potential degradation verification, and high‑voltage aging tests for crystalline silicon, thin‑film and other PV modules, providing standardized design guidelines for the localization and performance improvement of domestic PV test equipment.
Addressing core challenges including long continuous stable output, high temperature/humidity compatibility, high insulation and high reliability for PV PID testing, the solution adopts a main architecture of **front‑end isolated DC‑DC conversion + bipolar linear regulated output + fully sealed weatherproof insulation + fully digital long‑cycle closed‑loop control**, combined with long‑life moisture‑resistant components and environmental adaptive compensation algorithms. It eliminates traditional weaknesses such as poor long‑term stability and insulation failure under harsh humidity, achieving over 1000 hours of uninterrupted stable operation with voltage stability within ±0.3%/1000h, fully covering full‑cycle PID testing requirements. Five core principles are defined. First, the bipolar isolated topology delivers wide‑range −1500V~+1500V high‑voltage output for different module types. Symmetric quasi‑resonant flyback isolation achieves high‑voltage boost and complete electrical isolation with insulation withstand ≥5kVAC, separating high‑voltage circuits from low‑voltage control for safety. Dual positive/negative channels support negative bias for crystalline silicon and positive bias for thin‑film PID testing. Rear‑end high‑voltage linear regulation eliminates switching ripple with peak‑to‑peak ripple ≤0.1% FS and excellent power ripple rejection, ensuring ultra‑stable long‑term output. Modular multi‑channel independent design enables separate voltage setting, startup/shutdown and protection with full electrical isolation between channels, improving efficiency for mass production batch testing. Second, long‑term stability optimization enhances performance through premium component selection, precise closed‑loop control, advanced thermal management, and aging compensation. Long‑term high‑reliability industrial/military components are adopted: high‑voltage MOSFETs with leakage ≤1μA@1500V, ultra‑low drift voltage references ≤1ppm/℃, high‑precision metal foil resistors ≤2ppm/℃, and long‑life polypropylene film capacitors with no electrolyte drying risk. A 24‑bit ADC / 16‑bit DAC fully digital closed‑loop system updates at ≥10kHz to correct tiny deviations, achieving control accuracy better than ±0.2% FS. Built‑in aging adaptive compensation models drift over runtime, temperature and voltage variations to maintain stability within ±0.3% over 1000 hours. Full conduction cooling keeps power device junction temperatures below 60% of rated values; references and sampling circuits are housed in independent constant‑temperature chambers with fluctuation ≤±0.5℃ to eliminate thermal drift. Third, high temperature/humidity adaptability adopts a three‑level protection system of weatherproof materials, fully sealed insulation, and moisture/mold prevention for stable insulation under 85℃/85% RH. PCB substrates use high‑temperature/humidity resistant FR‑4 with 80~120μm polyurethane conformal coating against moisture and mold. High‑voltage insulators adopt PEEK/PTFE with insulation strength ≥20kV/mm without obvious degradation under humidity. Stainless steel enclosures achieve IP67 sealing with glass‑sealed connectors and waterproof cable glands. Internal dry nitrogen maintains slight positive pressure with molecular sieves keeping internal humidity ≤10% RH to prevent partial discharge and creeping flashover. Integrated alumina ceramic high‑voltage bushings ensure airtight insulation. All nonmetallic materials meet Grade 0 mold resistance; enlarged electrical clearance and creepage distances (50% higher than standard) prevent insulation breakdown. Fourth, high‑precision leakage current monitoring and PID adaptation support accurate micro current detection. A differential shielding sampling amplifier covers 0.1μA~100mA with accuracy ≤±0.5% FS and 10nA resolution to monitor insulation degradation and trigger rapid protection during breakdown. Standard embedded test templates fully comply with IEC 62804 and GB/T 37409 for automatic voltage ramping, dwell, recording and shutdown. Synchronous multi‑channel startup ensures identical test conditions for comparability. Full lifecycle data logging with flexible sampling intervals supports over 1000‑hour recording and standard report generation, enabling seamless synchronization with environmental chambers, solar simulators and IV testers for fully automated combined PID/IV/EL testing. Fifth, comprehensive dual hardware/software protection includes overvoltage, overcurrent/short circuit, leakage overlimit, arc detection, overtemperature, internal humidity alarm, door interlock and emergency stop. All hardware protection uses independent analog circuits with response ≤1μs. High‑frequency arc detection cuts high voltage instantly within 1μs upon discharge caused by breakdown or loose wiring to avoid fire risks. High‑voltage interlock enables output only with closed safety doors; residual voltage is discharged below safe levels within 50ms. Dual independent grounding with resistance ≤0.1Ω and real‑time insulation monitoring prevent electric shock hazards.
Long‑term stability and environmental adaptability form the core of this methodology. Four optimization dimensions cover long‑term drift compensation, high humidity insulation reinforcement, anti‑interference design, and full lifecycle reliability verification. Long‑cycle drift suppression establishes multi‑dimensional aging and temperature coupling models based on 1000+ hours of component endurance testing, enabling real‑time adaptive correction of reference voltage and control parameters to maintain deviation ≤±0.3%. Automatic full‑range calibration eliminates systematic errors without manual intervention. Multi‑stage isolated low‑noise power supplies stabilize reference and sampling circuits against grid fluctuation interference. High temperature/humidity insulation optimization adopts finite element electric field simulation for smooth rounded high‑voltage structures to eliminate field concentration, keeping maximum field strength below 20% of material breakdown limits. Creepage distances are doubled with umbrella‑shaped insulators ≥10mm/kV; plasma surface treatment enhances hydrophobicity against condensation flashover. Internal humidity monitoring triggers warnings at 10% RH and automatic shutdown at 20% RH. All components support −40℃~+125℃ with junction temperatures controlled below 70% under high heat. Strong anti‑interference design employs fully differential sampling with CMRR ≥120dB, multi‑stage filtering, TVS surge suppression, EMI shielding, fully enclosed metal shielding enclosures ≥80dB attenuation, and optical isolation for control signals. Digital filtering including moving average, median filtering and Kalman filtering suppresses noise; power frequency synchronous sampling eliminates coupled interference. Full lifecycle reliability validation enforces strict environmental cycling, long‑term aging, vibration shock and insulation withstand tests, including continuous 1000‑hour high humidity operation and 2000‑hour full‑load endurance with zero failure. Embedded self‑diagnosis monitors reference units, sampling circuits and power devices for early failure warning to avoid test interruption.
This methodology delivers a complete technical framework from stable long‑term topology and high humidity optimization to drift compensation and comprehensive safety protection, resolving critical drawbacks of traditional power supplies such as poor endurance, insulation failure and incompatibility with ultra‑long PID testing. Linear regulation plus adaptive drift control achieves ±0.3% stability over 1000 hours; three‑level environmental protection maintains insulation reliability at 85℃/85% RH; high‑precision differential sampling realizes nA‑level leakage detection, fully meeting IEC 62804 and GB/T 37409 standards. Widely applicable to PV module R&D, mass inspection and outdoor reliability evaluation, it provides core technical support for domestic substitution and performance upgrading of China’s PV test equipment.