Application Guide

How to Apply for (Senior) Product Engineer (m/f/d)

at 1KOMMA5°

🏢 About 1KOMMA5°

1KOMMA5° is a fast-growing climate tech company on a mission to make buildings CO2-neutral by integrating decentralized clean energy, mobility, and heat solutions. Their holistic approach—combining hardware, software, and AI—sets them apart in the green energy space, offering a unique opportunity to work on products that directly combat climate change.

About This Role

As a (Senior) Product Engineer, you'll own AI-powered features end-to-end, from problem framing to production deployment, working closely with PMs to build LLM-driven experiences for clean energy management. This role is impactful because you'll shape how users interact with decentralized energy systems, making sustainability intuitive and accessible at scale.

💡 A Day in the Life

Your day might start with a standup discussing progress on an AI-powered feature for optimizing home energy usage, then you'd dive into prototyping a new LLM-based chatbot for customer support. After lunch, you'd review user analytics from a recent deployment, iterate on the feature based on feedback, and end the day pairing with a PM to define scope for the next sprint.

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Interview Prep

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🎯 Who 1KOMMA5° Is Looking For

  • A fullstack engineer with deep TypeScript expertise (React/Next.js + Node.js/NestJS) who has shipped production-grade features with LLMs or AI APIs—not just toy projects.
  • Someone who thinks like a product owner: they prioritize user outcomes over technical perfection and can articulate how a feature solves a real customer problem.
  • A self-starter who thrives on owning the entire lifecycle—from vague requirements and prototyping to deployment, monitoring, and iteration based on user feedback.
  • Comfortable with ambiguity and fast feedback loops: they prototype quickly, ship to real users, observe behavior, and adjust without over-engineering.

📝 Tips for Applying to 1KOMMA5°

1

In your resume and cover letter, explicitly highlight one or two features you built end-to-end with LLMs or AI APIs—describe the problem, your approach, and the impact on users.

2

Show your product mindset: include a brief case study of a time you prioritized a user need over technical elegance, and how that decision paid off.

3

Tailor your portfolio or GitHub to include a demo or link to a live project using AI/LLMs—production experience is preferred, so a deployed app is a big plus.

4

Mention any experience with clean energy, IoT, or smart home systems—even if tangential—to show domain interest and fit with 1KOMMA5°'s mission.

5

Prepare a short (1-minute) video or written explanation of how you'd approach building an AI-powered feature for a smart home energy dashboard—be specific about tech stack and user feedback loops.

✉️ What to Emphasize in Your Cover Letter

['Emphasize your end-to-end ownership of features: describe a specific project where you took something from problem statement to shipped product, including AI integration.', 'Show your product and customer mindset: give an example of how you used user feedback to pivot or improve a feature, and the measurable outcome.', "Connect your work to 1KOMMA5°'s mission: explain why you're passionate about decarbonizing buildings and how your skills can accelerate that goal.", "Highlight your fullstack TypeScript proficiency and experience with LLMs in production—mention specific tools (e.g., LangChain, Vercel AI SDK, OpenAI APIs) you've used."]

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🔍 Research Before Applying

To stand out, make sure you've researched:

  • → Explore 1KOMMA5°'s product lineup (e.g., their energy management platform, smart home devices) to understand how AI could enhance user experience.
  • → Read about their 'Heartbeat' platform or any public case studies on how they integrate solar, heat pumps, and EV charging.
  • → Understand the German energy market and regulations (e.g., EEG, smart meter rollout) to grasp the context of their solutions.
  • → Look at their engineering blog or tech talks (if any) to learn about their tech stack, architecture, and AI integration patterns.

💬 Prepare for These Interview Topics

Based on this role, you may be asked about:

1 Walk me through a feature you built end-to-end with an LLM—how did you define success, and what trade-offs did you make?
2 How would you design an AI-powered feature for a smart home energy system that suggests optimal charging times for an electric vehicle?
3 Describe a time you had to balance speed vs. quality when shipping a feature. What did you learn from the outcome?
4 How do you approach integrating an LLM API (e.g., OpenAI) into a Node.js backend while keeping latency low and costs manageable?
5 What's your process for getting early user feedback on a prototype, and how do you decide when to iterate vs. pivot?
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⚠️ Common Mistakes to Avoid

  • Don't focus solely on frontend or backend—this is a fullstack role with AI emphasis. Highlight both sides, especially Node.js and LLM integration.
  • Avoid generic statements about being a 'team player' or 'passionate about tech.' Instead, give concrete examples of product ownership and AI work.
  • Don't overlook the 'customer mindset' requirement. If your examples are all about technical challenges without user impact, you'll seem misaligned.

📅 Application Timeline

This position is open until filled. However, we recommend applying as soon as possible as roles at mission-driven organizations tend to fill quickly.

Typical hiring timeline:

1

Application Review

1-2 weeks

2

Initial Screening

Phone call or written assessment

3

Interviews

1-2 rounds, usually virtual

✓

Offer

Congratulations!

Ready to Apply?

Good luck with your application to 1KOMMA5°!

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