ON.energy is building the power infrastructure that makes the AI era possible. As AI demand surges past what the grid and traditional data centers can support, ON.energy provides a new class of power technology proven at gigawatt scale and trusted by the world’s leading cloud and AI companies. Our systems are already deployed across 2.5 GW of hyper-scale campuses, validated by top U.S. national labs, and certified for grid-safe operation by major utilities. With real products in the field, we’re scaling faster than the grid can, transforming power from a bottleneck into a competitive advantage for the companies building the future.
ROLE OVERVIEW
The Testing Engineer will support the Test Lead in the design, technical sizing, integration, and execution of tests for Battery Energy Storage Systems (BESS) and Grid-Following/Grid-Forming (GFL/GFM) systems within ON.energy’s Research and Development area. The engineer will assist with product development, validation, and risk mitigation activities, collaborating in the planning and execution of validation cycles in the testing laboratory under the supervision of the Test Lead, to whom they will report directly.
The main objectives are to mitigate system architecture risks for ON.energy’s current and future product lines through rigorous laboratory stress testing, bridge the gap between laboratory results and real-world conditions, and support training, troubleshooting, and customer engagement activities.
KEY RESPONSIBILITIES
Design, Sizing, and Integration
Design and Sizing - Support the calculation and sizing of BESS systems (capacity, power, discharge rate, operating cycles, and efficiency) and GFL/GFM solutions according to project requirements.
Component Selection - Support the selection and integration of appropriate components based on the application (peak shaving, power quality, HIL, dynamic test profiles, etc.), including batteries, BMS, inverters, protection devices, and cabling.
Electrical Engineering - Assist in preparing single-line electrical diagrams, calculation reports, and bills of materials supporting each solution.
Test Planning
Test Protocol Development - Design and document detailed testing procedures utilizing Hardware-in-the-Loop (HIL) laboratory assets to validate the performance of BESS and GFL/GFM systems under extreme conditions (e.g., fast frequency response, grid and load transitions, or grid instability). Translate product design criteria, industry standards, and customer requirements into detailed work plans.
Test Coordination - Support the technical implementation of each test, from pre-test documentation (test plans) through results generation and documentation (test reports).
Compliance and Safety - Contribute to ensuring that all ON.energy testing hardware and procedures comply with industry safety regulations, applicable technical standards, and local laboratory operating protocols.
Risk Mitigation and Technical Validation
Failure Mode Discovery - Support the use of the controlled laboratory environment to identify edge-case failures that are impossible to test in real-world field conditions.
Data Analysis - Support the analysis of high-fidelity data streams from laboratory sensors to provide actionable feedback to ON.energy product and project teams, as well as component suppliers, for firmware and hardware iterations.
Verification - Execute planned functional tests under the direction of the Test Lead and report collected data against product requirements and performance criteria for internal and customer review.
Documentation and Knowledge Transfer
Manual Development - Support the conversion of laboratory-based learnings into field-ready commissioning documents and troubleshooting guides.
Training - Assist in coordinating training plans to ensure consistent knowledge transfer across the commissioning department.
EXPERIENCE AND REQUIREMENTS
Bachelor’s degree in Electrical Engineering, Electro-Mechanical Engineering, Mechatronics, Renewable Energy, or a related field (completed degree required).
Minimum of 1 year of verifiable experience in the design, integration, testing, or installation of energy storage systems (BESS), power electronics, or electrical installations. Internships, co-op programs, and social service experience in related areas are also valued. Experience in testing and modeling compliance with grid codes for inverter-based resources, as well as field installation or technical supervision, is desirable.
Basic knowledge of Battery Energy Storage Systems (BESS), Power Electronics (inverters/rectifiers), and Grid-Following/Grid-Forming (GFL/GFM) technologies. Familiarity with applicable standards and regulations (NOM, NEC; IEC preferred).
Calculation and sizing of BESS systems (capacity, power, discharge rate, cycles, efficiency); technical component selection (batteries, BMS, inverters, protection devices, cabling); ability to read and interpret single-line electrical diagrams; preparation of technical documentation (calculation reports, diagrams, bills of materials). Basic knowledge of or willingness to learn AutoCAD, Excel, and energy sizing tools (preferred: HOMER, MATLAB/Simulink, PVSyst).
Experience operating in a physical laboratory environment, including setup and use of hardware such as oscilloscopes, multimeters, power meters, power supplies, generators, and load banks for system validation.
Courses and Certifications (Preferred) - NFPA 70E certification/training, Lockout/Tagout (LOTO), fire extinguisher handling, and first aid.
Knowledge of or interest in HIL (Hardware-in-the-Loop) testing environments and MATLAB/Simulink, with basic understanding of SCADA systems and Modbus/TCP communications.
Logical and analytical thinking, proactive problem-solving abilities, teamwork in multidisciplinary environments, and effective communication with operational and commercial teams.
Strong communication skills—the ability to speak the language of “Research” with technical and R&D teams and the language of “Implementation” with ON.energy field technicians.
Intermediate to advanced English, minimum B2/C1 level. The position requires frequent interaction in English with suppliers and ON.energy internal customers.
LOCATION AND WORK MODALITY
This is a 100% on-site position at ON.energy’s testing laboratory located in Villahermosa, Tabasco, Mexico. The role requires permanent physical presence in the laboratory for equipment operation, test execution, and technical support; it is not a remote or hybrid position.
The position is performed entirely on-site at ON.energy’s laboratory in Villahermosa, Tabasco, Mexico, with occasional travel to other ON.energy project sites for the transition of validated technologies.
For US-based roles - What you’ll get:
Competitive salary + annual performance-based bonus eligibility
Medical, dental, and vision insurance
401(k) with company match
Paid time off and company holidays
For Mexico-based roles - What you’ll get:
Competitive salary + annual performance bonus eligibility
Christmas Bonus (Aguinaldo): 30 days
Major medical expenses and life insurance
Paid time off and holidays (per local policy)
For all roles:
Professional development and growth opportunities
Opportunity to grow with a mission-driven team shaping the future of clean energy
Equal Opportunity: ON.energy is committed to equal employment opportunity and to maintaining a work environment free of harassment, discrimination, or retaliation.
Accommodations: If you need an accommodation during the application process, email recruitment@onenergystorage.com
Benefits vary by role and location and are subject to change.