Type · motivation
What specifically about 1KOMMA5°'s mission to accelerate the energy transition and our focus on smart energy solutions excites you most as a software engineer?
How to Pass the 1KOMMA5° Software Engineer Interview in 2026
The 1KOMMA5° DNA (TL;DR)
1KOMMA5°'s 'Hand Heartbeat' principle guides assessments, seeking individuals who can drive the energy transition with practical impact. Interviewers look for tangible contributions to projects like Solaranlage Wie, demonstrating initiative and a clear vision for sustainable solutions.
The 1KOMMA5° Interview Loop
Your onsite loop will typically consist of 5 rounds.
- 1
Round 1
Recruiter ScreenMotivation, role fit, logistics. - 2
Round 2
Coding ScreenLeetCode-medium algorithmic problems under time pressure. - 3
Round 3
System DesignDistributed systems, trade-offs at scale, architecture under constraints. - 4
Round 4
Onsite CodingLeetCode-hard problems, reasoning about defects, code clarity, edge cases. - 5
Round 5
Behavioral / LeadershipPast evidence of ownership, influence, resolving conflict.
The Danger Zone: Top Reasons Candidates Fail
Based on our database of 1KOMMA5° interview outcomes, avoid these common traps:
- Proposing a solution that requires storing all historical data for every home, leading to excessive memory usage.
- Jumping straight into code changes without a clear hypothesis or plan.
- Inefficiently iterating through all data points within the range without leveraging any indexing or pre-computation.
- Ignoring the interaction between charging, discharging, and external energy sources/loads.
Test Yourself: Real 1KOMMA5° Questions
Three real prompts pulled from our database.
Type · algorithmic
Imagine you have a system that aggregates energy production data from solar panels across many households. Each household reports its production in kWh per minute. Write a function to calculate the total energy produced within a given time range (start_time, end_time) for a specific household, optimizing for performance when querying large datasets.
Type · architecture
1KOMMA5° is expanding its network of charging stations. Design a system to manage the charging status, availability, and billing for these stations. Consider how to handle concurrent charging sessions, potential hardware failures, and integration with payment gateways.
+ many more questions, signals, and worked examples
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1KOMMA5° Interview Question Bank
A sample from our database, grouped by round. Sign up to see the full set.
9 of 12 questions shown
1
Recruiter Screen
1- 1
Type · motivation
What specifically about 1KOMMA5°'s mission to accelerate the energy transition and our focus on smart energy solutions excites you most as a software engineer?
2
Coding Screen
3- 2
Type · algorithmic
Given a stream of energy consumption readings (timestamp, kWh) from thousands of smart homes, design an algorithm to efficiently detect anomalies (e.g., sudden spikes or drops) that deviate significantly from the typical consumption pattern for that specific home and time of day. You need to handle a high volume of data. - 3
Type · algorithmic
Imagine you have a system that aggregates energy production data from solar panels across many households. Each household reports its production in kWh per minute. Write a function to calculate the total energy produced within a given time range (start_time, end_time) for a specific household, optimizing for performance when querying large datasets. - + 1 more questions in this round (sign up to unlock)
3
System Design
3- 4
Type · architecture
Design a scalable system for 1KOMMA5° to manage and optimize energy flow for a network of interconnected smart homes. The system should be able to receive real-time data from smart meters and charging stations, predict demand/supply, and make automated decisions to balance grid load and minimize costs for users. Consider data ingestion, processing, storage, and decision-making components. - 5
Type · architecture
How would you design a system to provide personalized energy-saving recommendations to users based on their historical consumption patterns, weather forecasts, and electricity tariff information? Consider the data sources, processing logic, and how recommendations are delivered. - + 1 more questions in this round (sign up to unlock)
4
Onsite Coding
2- 6
Type · algorithmic
You are given a list of time intervals, where each interval represents a period a smart home was actively consuming or producing energy (e.g., `[start_time, end_time, type]`, where type is 'consume' or 'produce'). Write a function to calculate the total duration of 'consume' periods that overlap with 'produce' periods for a given day, considering that a home might consume and produce simultaneously (e.g., using solar power while also drawing from the grid). - 7
Type · algorithmic
Design and implement a function that simulates the charging/discharging of a home battery system. The function takes the current battery level, desired state of charge (SoC), electricity price, and a schedule of energy production/consumption events. It should decide whether to charge, discharge, or do nothing at each time step to optimize for cost savings, given the battery's charge/discharge rate limits and capacity.
5
Behavioral / Leadership
3- 8
Type · ownership
Tell me about a time you encountered a significant technical challenge in a project related to energy systems or data. How did you take ownership of the problem, what steps did you take to resolve it, and what was the outcome? - 9
Type · collaboration
At 1KOMMA5°, we often balance the trade-off between prioritizing immediate feature delivery for a specific hardware integration and building a more generic, scalable backend architecture. Describe a specific instance where you advocated for a long-term architectural improvement against a push for a quick tactical fix. How did you quantify the technical debt, and how did you align your team on the long-term benefit? - + 1 more questions in this round (sign up to unlock)
Unlock all 12 1KOMMA5° questions, free
No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.
Interview tracks at 1KOMMA5°
How 1KOMMA5°'s DNA translates across functions. Pick your role.
Compare 1KOMMA5° with similar employers
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Practice 1KOMMA5° interviews end-to-end
1KOMMA5° Mock Interview
Run a live mock interview with our AI interviewer using 1KOMMA5°-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.
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STAR Stories for 1KOMMA5° Behavioral Rounds
Build a Story Bank of your past wins, mapped to the leadership signals 1KOMMA5° interviewers grade on. Reuse them across every behavioral round.
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1KOMMA5° Interview Prep Hub
The frameworks behind every 1KOMMA5° round: CIRCLES for product sense, hypothesis-driven debugging for analytical, STAR for behavioral. Learn each one in 10 minutes.
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Interview Frameworks
CIRCLES, STAR, AARRR, RICE, MECE. The exact frameworks that make 1KOMMA5° interviewers nod instead of frown. Step-by-step playbooks with the moves and the pitfalls.
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Sample answers
What a strong answer to these 1KOMMA5° interview questions shows.
What specifically about 1KOMMA5°'s mission to accelerate the energy transition and our focus on smart energy solutions excites you most as a software engineer?
A strong answer shows: Specific mention of 1KOMMA5°'s products or services (e.g., smart meters, charging infrastructure, energy management software).; Articulates a connection between their skills and the company's impact on the energy market..
Imagine you have a system that aggregates energy production data from solar panels across many households. Each household reports its production in kWh per minute. Write a function to calculate the total energy produced within a given time range (start_time, end_time) for a specific household, optimizing for performance when querying large datasets.
A strong answer shows: Proposes using data structures like sorted lists or interval trees for efficient range queries.; Discusses potential pre-aggregation strategies for common time windows.; Writes clear, well-tested code..
Frequently asked questions
How long does the 1KOMMA5° interview process take?
Most candidates spend between 4 and 8 weeks from recruiter screen to offer. The onsite loop itself runs in a single day or is split across two half-days, with debrief and offer typically within 5 business days after.
How should I prepare specifically for 1KOMMA5°?
Focus on three things: (1) the company DNA shown above - what they actually grade for, (2) the rounds in your loop, especially the round most candidates underestimate, and (3) drilling on the question types in this guide using a structured framework like CIRCLES or STAR.
Does this apply to engineering or design roles at 1KOMMA5°?
The DNA stays the same - what changes is the round mix. SWE candidates face coding screens instead of Product Sense; designers face portfolio reviews and design exercises. The "what they value" and behavioral signals carry across all functions.
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