How to apply for Staff Engineer - Heartbeat AI (m/f/d)

About 1KOMMA5°

1KOMMA5° builds CO2-neutral buildings using decentralized clean energy, mobility, and heat solutions. The company operates a virtual power plant that connects solar, batteries, heat pumps, and e-mobility directly to the electricity market in real time. It has over 3,000 employees across more than 80 locations, from Finland to Australia, with a goal to transition 1.5 million households to renewable energy by 2030.

About the role

As a staff engineer for Heartbeat AI, you own the technical direction across mobile apps, energy data, and the IoT platform. You are accountable for consistent execution of technical decisions in your domain and set the technical bar by solving the hardest problems yourself. This role directly shapes the software that controls distributed energy assets and interacts with electricity markets.

A typical day

A typical day might involve reviewing architecture proposals for the IoT platform, pairing with engineers on a hard data pipeline issue, and aligning with product managers on technical direction for mobile apps. You would also spend time on your own coding or design work for the most difficult problems in the domain. Exact routines depend on the team, so ask about daily collaboration and on-call expectations during interviews.

Who 1KOMMA5° is looking for

• Has experience owning architecture for complex systems that combine mobile apps, real-time data, and IoT or hardware integration.
• Can make and enforce technical decisions across multiple teams, not just one codebase.
• Is hands-on and willing to personally tackle the most difficult engineering problems rather than only directing others.
• Understands energy markets, virtual power plants, or similar real-time operational technology (or can learn the domain quickly).

Tips for this application

• In your resume, list concrete systems you have architected that involve mobile apps, streaming data, or IoT devices. Include scale numbers (devices, messages per second, users).
• Mention any experience with energy data, electricity markets, or virtual power plants. If you lack it, describe a comparable real-time system you have built.
• Use the cover letter to explain how you have set technical direction across teams and held engineers accountable for implementation.
• Provide an example where you personally solved a hard technical problem instead of delegating it. This role explicitly values stepping into the hardest problems.
• Check the 1KOMMA5° Product & Tech team page before applying and refer to a specific product or technology from that page in your application.

What to cover in your cover letter

['Your experience defining architecture across mobile, data, and IoT domains, and how you kept it aligned with product direction.', 'A specific case where you made a technical decision, communicated it clearly, and ensured the team executed it consistently.', 'A hard technical problem you solved yourself, with details on the problem, your approach, and the outcome.', 'Why you want to work on Heartbeat AI and the virtual power plant, and how your background fits the energy domain.']

Research before applying

• Read the 1KOMMA5° Product & Tech team page to understand the current tech stack and product areas.
• Research how virtual power plants work and how they connect to electricity markets in real time.
• Look up Heartbeat AI specifically and any public information about its role within 1KOMMA5°.
• Find out which countries 1KOMMA5° operates in and what energy market rules or grid constraints might affect the software.

Likely interview topics

Based on the job description, expect questions about:

• How you would set technical direction for Heartbeat AI across mobile apps, energy data, and the IoT platform while keeping architecture aligned with product goals.
• A time you held a team accountable for implementing a technical decision and how you handled resistance or drift.
• A deep technical problem you solved hands-on in a real-time data or IoT system, including trade-offs you made.
• How you would design or improve a system that controls solar, batteries, heat pumps, and e-mobility based on electricity market signals.
• How you prioritize technical debt, reliability, and feature work in a domain where real-time energy decisions have financial and operational impact.

Common mistakes to avoid

• Applying as a pure people manager or architect who no longer codes. This role requires stepping into the hardest problems yourself.
• Focusing only on mobile or only on data. The role spans mobile apps, energy data, and IoT platform, so show breadth.
• Ignoring the energy domain. Even if you have not worked in energy, show that you understand why real-time market integration matters for this role.