Sr. Thermal Engineer

Job Description:

About Nextpower Nextpower is a global leader in intelligent solar tracker and software solutions, optimizing solar power plant performance worldwide. Our cutting-edge technology and commitment to innovation drive the renewable energy transition.

Sr. Thermal Engineer – Hybrid role (4x per week onsite) based at headquarters in Fremont, California. The Sr. Thermal Engineer will report to the Director, Power Electronics Mechanical Engineering.

We are seeking a Sr. Thermal Engineer to lead the thermal design, analysis, testing, and validation of advanced thermal management solutions for power electronics systems. This role will serve as a key technical expert in solving complex thermal challenges through modeling, hands‑on test development, and practical implementation of cooling solutions including conduction, convection, and phase‑change methods.

• Lead the thermal architecture, design, analysis, prototyping, and validation of power electronics enclosures and related systems.
• Own thermal simulations and engineering analyses, including steady‑state and transient thermal modeling, CFD analysis, and correlation of simulation results to test data.
• Develop and implement thermal management solutions using methods such as heat sinks, heat spreaders, thermal interface materials, heat pipes, vapor chambers, airflow design, and other passive or active cooling techniques.
• Define thermal requirements, test strategies, and acceptance criteria for new product designs.
• Develop comprehensive thermal test plans; design and build test fixtures and apparatus; select instrumentation; and execute thermal characterization and validation testing.
• Analyze test data to identify hot spots, thermal bottlenecks, derating risks, and reliability concerns, and drive design improvements based on findings.
• Work closely with cross‑functional teams and external partners to ensure thermal solutions meet system, cost, manufacturability, reliability, and schedule requirements.
• Create clear engineering documentation to support prototype, design verification, and production phases.
• Present thermal design reviews, analysis results, and technical recommendations to internal stakeholders and management.
• Investigate field failures and product performance issues, perform root‑cause analysis of thermal problems, and lead corrective actions.

• Bachelor’s or Master’s degree in Mechanical Engineering or a related field.
• Minimum of 5 years of experience in thermal management of power electronics or electronics cooling systems.
• Expert‑level proficiency in CFD and thermal simulation tools such as FloTHERM or Icepak.
• Deep understanding of heat transfer principles, including conduction, convection, radiation, and phase‑change cooling methods.
• Strong experience in thermal analysis, simulation‑to‑test correlation, and design optimization.
• Hands‑on experience developing thermal test methods, instrumentation setups, and validation plans for thermal systems.
• Experience designing and troubleshooting practical thermal solutions, including heat sinks, heat pipes, vapor chambers, thermal interface materials, and enclosure‑level cooling strategies.
• Knowledge of manufacturing processes relevant to thermal components and assemblies.
• Demonstrated experience applying DFM/DFA principles in product development.
• Strong analytical and problem‑solving skills, with the ability to diagnose and resolve complex thermal performance issues.
• Excellent communication, interpersonal, and presentation skills.
• Proven ability to work independently and collaboratively in cross‑functional teams.
• Familiarity with relevant industry standards and regulations.

Nextpower offers a comprehensive benefits package. We provide health care coverage, dental and vision, 401(k) participation including company matching, company‑paid holidays with unlimited paid time off, generous discretionary company bonuses, life and disability protection, and more. Employees in certain positions may be eligible for stock compensation. All plans are in accordance with relevant plan documents.

Pay is based on market location and may vary based on factors including experience, skills, education and other job‑related reasons. The annual salary range for this position is Pay Range (Applicable to California) $ - $, dependent on level of experience.

Nextpower is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.