Principal Reliability Engineer

Enphase Energy is a global energy technology company and a leading provider of solar, battery, and electric vehicle charging products. Founded in 2006, our innovative microinverter technology revolutionized solar power, making it a safer, more reliable, and scalable energy source. Today, the Enphase Energy System enables users to make, use, save, and sell their own power. Enphase is also one of the most successful and innovative clean energy companies in the world, with more than 80 million products shipped across 160 countries.
Join our dynamic teams designing and developing next-gen energy technologies and help drive a sustainable future!
Principal SST Reliability Lead
About the Role
The SST Product Innovation Team in the Office of the CTO defines, prototypes, and scales Enphase's next-generation power systems. Solid-state transformers operate under extreme stress — MV switching at high frequency, wide ambient swings, thousands of thermal cycles per year, and 20+ year field life. We need a Reliability Lead who can translate real-world workload and environmental stress into quantitative test plans that expose failure modes before they reach the field.
You will own reliability from architecture through production — mission profiles, physics-of-failure models, accelerated life tests, and data-driven design changes. Hands-on with hardware, embedded in the design team, accountable for product lifetime.
What You Will Do
Define and own the SST mission profile: Translate deployment conditions (load profiles, duty cycles, ambient temperatures, humidity, on/off cycling, grid transients) into a quantitative mission profile that drives all reliability testing. Update as field data becomes available.
Design workload-based accelerated life tests (ALT): Build test plans using physics-of-failure models (Arrhenius, Coffin–Manson, Norris–Landzberg, inverse power law). Define acceleration factors, sample sizes, durations, and pass/fail criteria per failure mode.
Lead thermal and power cycling testing: Execute thermal cycling (-40°C to +85°C+), power cycling, and active thermal cycling on power modules, solder joints, wire bonds, and DBC substrates. Correlate to field lifetime via mission-profile acceleration.
Drive DFMEA/PFMEA: Lead cross-functional FMEA sessions tied to real test data. Track RPNs and drive corrective actions to closure.
Own HALT/HASS strategy: Run HALT during design to find margins and failure modes. Develop HASS profiles for production screening.
Build physics-of-failure models: Develop reliability models for SiC modules (bond wire, solder, die-attach), capacitors, magnetics, gate driver isolation, and connectors.
Write reliability test specs: Specs tied to mission profile, not generic IEC/UL conditions. Define stress conditions, load profiles, sample sizes (Weibull-based), readout intervals, and failure criteria.
Integrate reliability into design: Participate in design reviews from concept through production. Flag high-risk areas early and drive design changes before they get expensive.
Champion DfR: Train engineers on mission-profile thinking, derating, thermal margins, and power electronics failure mechanisms.
Collaborate across disciplines: Work with PE, thermal, mechanical, FW, and manufacturing teams. Partner with suppliers on component qualification.
Who You Are and What You Bring
BS, MS, or PhD in Mechanical Engineering, Electrical Engineering, Materials Science, Reliability Engineering, or closely related field
Principal Engineer: BS + 15 yrs | MS + 12 yrs | PhD + 8 yrs
Candidates with greater experience are strongly encouraged to apply
Mission profile development — required: Experience translating real-world use conditions (load profiles, duty cycles, environmental exposure, on/off cycling, grid transients) into quantitative mission profiles. Must understand calendar vs. operational aging and how workload severity affects lifetime.
Physics-of-failure modeling — required: Ability to build models using Arrhenius, Coffin–Manson, Norris–Landzberg, and inverse power law. Must derive acceleration factors from first principles.
ALT design — required: Hands-on experience designing workload-based accelerated life tests. Defining acceleration factors, Weibull-based sample sizes, test-to-field correlation, and pass/fail criteria tied to B10 or MTTF targets.
Thermal and power cycling testing — required: Direct experience with thermal shock, thermal cycling, and power cycling on power modules, solder joints, and PCBs. Understanding of ΔTj effects and dwell time sensitivity.
DFMEA/PFMEA leadership — required: Leading cross-functional FMEA sessions with severity/occurrence/detection ratings grounded in real data.
Weibull and life data analysis — required: Proficiency with Weibull++, JMP, Minitab, or Python/R. Fitting Weibull, lognormal, and competing-risk models to censored data. Bayesian updating and degradation modeling.
Failure analysis: Root cause using cross-sectioning, SEM/EDS, X-ray, acoustic microscopy, dye-and-pry, curve tracing, and therma