About this role.
Lunar Energy is hiring a Staff Firmware Engineer to develop reliable embedded software for clean-energy home products. The role covers the full firmware lifecycle, including wireless communications, system architecture, diagnostics, updates, and production-quality ownership. The engineer will work with C, Python, Wi-Fi, Ethernet, TCP/UDP/HTTPS, Bluetooth/BLE, and the Espressif ecosystem. This is a hands-on cross-functional position focused on always-on, high-volume products and resilient customer operation. The role suits an experienced embedded engineer motivated by sustainable energy technology.
Role DNA
A quick view of the complexity, pace, ownership and collaboration implied by the job description.
Job Complexity
5/5Pace & Pressure
4/5Autonomy Level
5/5Communication Load
4/5Salary analysis
Estimated compensation compared with the broader US market for similar roles.
Core skills
Skills and capabilities most closely associated with this opportunity.
Sample interview questions
I would explain the product requirement, architecture choices, implementation in C, validation approach, manufacturing or field rollout process, and measurable reliability or performance results. I would also describe issues discovered during integration and how I resolved them.
I would first collect structured telemetry and reproduce the issue across network conditions. I would inspect association, DHCP, DNS, TCP/TLS, power-state transitions, RF conditions, and firmware logs, then use packet captures and targeted fault injection to isolate the failure and validate a durable fix.
I prioritize explicit state machines, watchdog and recovery strategies, bounded resource use, robust error handling, persistent diagnostics, safe over-the-air update mechanisms, and extensive stress testing. I also design for degraded operation so that transient network or peripheral failures do not compromise core safety or functionality.
I use them to correlate firmware behavior with physical signals, such as checking timing, reset sequencing, bus transactions, interrupts, and power integrity. I form a hypothesis from logs and source code, capture the relevant signals, identify the discrepancy, and confirm the correction with repeatable tests.
I begin by aligning on user needs, constraints, interfaces, risks, and success metrics. I present viable options with trade-offs, document decisions and ownership, and ensure the selected design has a practical validation and rollout plan that all disciplines can support.
Staff Firmware Engineer
Embedded/Firmware Engineers at Lunar will be responsible for the full product development lifecycle of our products’ firmware and software, which are important sources of functionality, adaptability, and optimization of our designs. We are looking for people who are passionate about a more sustainable future, and want to make that vision a reality. An ideal candidate is excited and ready to collaborate closely with a dedicated, cross-functional team to deliver innovative, best-in-class products. Engineers at Lunar are hands-on and involved in all aspects of the product, and own the design from forming concepts based on first principles to managing high-volume production quality.
Lunar Energy was founded to transition homes to 100% clean energy—making our electricity greener, our air cleaner and our energy more safe, secure and reliable for all. We’re a fast-growing, global company building the world’s best clean energy products to electrify all homes and connect communities to form clean, resilient virtual power plants.
On a given day at Lunar, you’ll likely…
- Develop wireless network communication solutions for high-volume products, ensuring continuous 24/7 reliability
- Design firmware software that runs in our home energy product components: RF communication protocols, mobile app interfaces, system diagnostics and updates.
- Drive design discussions on system architecture to achieve the desired product functionality.
- Collaborate with the team on design and development, including participating in code reviews.
- Work collaboratively with other disciplines across the company to continuously refine and improve our understanding of how our products can create the greatest impact, get to market quickly, and operate reliably for our customers
Desired Skills:
- Degree in a computer-engineering related or adjacent field, or demonstrated commensurate ability.
- 5+ years experience delivering firmware for new products as part of a team.
- Proficiency in C, and working familiarity with Python. Rust knowledge is nice to have.
- Experience working with IP stack protocols: Ethernet, WiFi, TCP, UDP, HTTPS, etc
- Working knowledge of Bluetooth/BLE.
- Experience working with WiFi networks and Espressif ecosystem
- Working knowledge of Oscilloscopes, Logic Analyzers and other lab test equipment
Benefits:
We’re dedicated to creating a remarkable employee experience. At Lunar, competitive base pay is one part of our total compensation package. Lunar employees also have the opportunity to become Lunar shareholders by getting equity in a fast-growing company and participating in our employee stock program.
Additional benefits include:
- Competitive salary and stock options package
- Private Medical Insurance scheme through BUPA (medical history disregarded)
- A wellbeing and lifestyle benefits plan through Medicash
- 5% employer contributions pension matching
- A budget for work related training of £1,000 per financial year and an allowance of 4 training days
- Cycle To Work scheme and Workplace Nursery benefit
- Access to Spill – Mental Health Support platform
- Enhanced Maternity + Paternity Pay
- 25 days annual holiday entitlement + 8 Bank Holidays
- Flexible start and finish times, fully remote working or hybrid depending on preferences
Our DE&I Philosophy: Lunar Energy is an equal opportunity employer. We are committed to attracting, developing and retaining diverse talent by supporting an inclusive workplace. Lunar recruits, hires, trains, promotes, compensates, and administers all personnel actions without regard to race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, disability status or any other status protected by applicable law.
Annual salary information is not provided for this position. Explore salary ranges for similar roles in our Salary Directory ›
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