Product Engineer

About Lumen Energy

Lumen Energy is the modern solar broker for the nation's largest commercial real estate owners. We partner with leading owners to turn underutilized rooftops into profitable solar revenue — delivering investment-grade analysis powered by our proprietary Lux Engine, securing transparent competition among top developers, and providing white-glove service throughout.

We work with leading institutional CRE customers including Nuveen, KKR, and J.P. Morgan Asset Management, and we're backed by Lowercarbon Capital and Designer Fund. The team comes from Stripe, Google X, Arcadia, and Siemens, united by a mission to power the built world with profitable clean energy.

The Role

We're looking for a Product Engineer who lives at the intersection of product and engineering. This is a high-impact role: you'll wear both product and engineering hats, driving features end-to-end from idea, through rapid prototyping, to polished production experiences. You'll shape what we build and why, not just how.

You'll report directly to our Head of Engineering and work cross-functionally with our entire team. This is a full-time, remote (US) role, with an SF office if you'd like one.

What You'll Do

• Drive product iteration and execution. Work with partners across Marketing, Sales, and Operations to identify product gaps, then carry solutions through conception, implementation, and maintenance

• Prototype rapidly with AI tools. Get tangible, testable experiences in front of customers and teammates early, and use their feedback to decide what deserves further investment

• Build and ship features end to end, from early prototype through production-ready code

Who You Are

• A prototyper, not just a builder. You get your work into people's hands and collect feedback. When a prototype is dead in the water, you say so and move on without getting attached. You are not precious about the things you build.

• An empathetic communicator. You express nuanced ideas clearly for different audiences, give and take direct feedback well, and prioritize curiosity over confrontation in disagreements

• A designer at heart. You hold a high bar for polished user experiences, catch quality issues others miss, and don't need pixel-perfect specs to know when something's off

• High ownership, low drama. When a problem is underspecified, you ask sharp questions, make reasonable assumptions, and keep moving. You follow through, flag blockers early, and close loops

• Motivated by mission. You want your work to advance the energy transition

Qualifications

Required:

• Proven track record of execution. You have 3–5+ years of experience in a product engineering, frontend, full-stack, or design engineering role

• Enough production experience to have real opinions about frontend architecture and tooling — you've seen good and bad in the wild and can tell the difference.

• Familiarity with our tech stack (or strong ability to learn new technologies quickly). Our current tech stack is Python, Flask, SQLAlchemy, PostgreSQL, Rust, TypeScript, React, GraphQL, Google Cloud Platform (See more about the code at the end of this posting)

• Demonstrated use of AI coding tools (Cursor, Claude, Codex, etc.) as a core part of your development workflow

Nice to Have:

• Experience in a startup or high-growth environment

• Background or genuine interest in climate tech or real estate

Who this role isn't for

We'd rather you know now than three interviews in:

• You want a large, specialized team. If you're looking for a big frontend guild, dedicated design systems teams, full-time product managers and designers, you’ll be disappointed. We all wear multiple hats.

• You prefer deep backend work. This role leans frontend. If you're a backend engineer who tolerates UI work rather than enjoying it, the day-to-day will feel misaligned.

• You want process and predictability. Early-stage startups have shifting priorities, incomplete specs, and decisions made in slack threads. If you need a well-oiled sprint machine, this will be frustrating.

About the interview

• Round 1 (45 minutes): Introduction call with Kerri Devine (Head of Engineering)

• Round 2 (90 minutes): Technical evaluation with engineering team

  • Architecture design review

  • AI coding collaboration exercise

• Round 3 (45 minutes): Cross-functional collaboration discussion with a non-engineer

• We may request subsequent interviews here if we didn’t get enough signal in a particular competency.

• (Optional): You’re welcome to have conversation(s) with your cross-functional peers to interview us.

About the code

$ scc --exclude-file generated -c --include-ext py,ts,tsx,rs
───────────────────────────────────────────────────────────────────────────────
Language                     Files       Lines     Blanks    Comments      Code
───────────────────────────────────────────────────────────────────────────────
Python                        2170      333107      36953       29104    267050
TypeScript                     998      289830      17549        8933    263348
Rust                            28       12889        750         462     11677
───────────────────────────────────────────────────────────────────────────────
Total                         3196      653826      55252       38499    542075

• We use Python with Flask+SQLAlchemy on the backend.

• We use TypeScript with React on the frontend.

• We wrote a few Rust modules for where performance matters.

  • Utility tariff rate calculations

  • Spreadsheet calculations: we wrote an Excel interpreter so that we can express financial calculations in the format our users understand.

• We use advanced tools to help us develop, but default to choosing boring technology to run our site. So far Postgres does a great job with just about everything we need to do.

• We rely on machines for automating type checks and deploys.

  • We use auto-formatters, and our Python code is just about fully type-annotated.

  • We use immutable data classes wherever possible.

  • Code changes are deployed automatically when tests pass. About 30% of our python code is tests.

• We believe that getting the data model right will let the rest of the code flow easily. We’ve rarely gotten the data model right the first time.

Why Lumen

• Work that matters. Every rooftop we convert accelerates decarbonization at scale

• High ownership, early on. You'll have real impact from day one, not years from now

• A team that moves fast and values clear thinking over politics or hierarchy

• Competitive salary, benefits, and equity participation

• A culture that embraces technology, including AI. We use new tools actively and encourage you to do the same

• Room to grow. We promote from within and invest in the development of our team

Lumen Energy is an equal opportunity employer. We celebrate diverse perspectives and are committed to building an inclusive workplace. US work authorization required. We are unable to sponsor H1B visas at this time.