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How to Pass the Terna Software Engineer Interview in 2026

Enterprise · Software Engineer Interview Guide

Interview language: English

The Terna DNA (TL;DR)

Terna's 'Driving Energy' strategic plan emphasizes candidates' capacity to innovate within grid modernization and sustainability, aligning with values like 'Integrity' and 'Meritocracy.' The interview loop seeks individuals who can articulate their contribution to complex infrastructure projects, demonstrating a forward-thinking approach to energy transition challenges.

The Terna Interview Loop

Your onsite loop will typically consist of 5 rounds.

1
Round 1
Recruiter Screen
Motivation, role fit, logistics.
2
Round 2
Coding Screen
LeetCode-medium algorithmic problems under time pressure.
3
Round 3
System Design
Distributed systems, trade-offs at scale, architecture under constraints.
4
Round 4
Onsite Coding
LeetCode-hard problems, reasoning about defects, code clarity, edge cases.
5
Round 5
Behavioral / Leadership
Past evidence of ownership, influence, resolving conflict.

The Danger Zone: Top Reasons Candidates Fail

Based on our database of Terna interview outcomes, avoid these common traps:

Inefficient data partitioning or indexing strategies.
Using a naive approach that iterates through all readings for each query.
Focusing on a simple traversal without considering load and capacity.
Lack of consideration for data volume and velocity from thousands of devices.

Test Yourself: Real Terna Questions

Three real prompts pulled from our database.

Type · algorithmic

Imagine Terna needs to optimize the real-time distribution of electricity across a complex grid to minimize losses and prevent overloads. Given a list of grid segments, their current load, and their capacity, design an algorithm to identify the most critical segments that, if overloaded, would cause cascading failures. You can assume a simplified graph representation of the grid.

Type · system-design

Design a system for Terna to monitor and predict potential faults in a large network of distributed energy storage units (e.g., batteries). The system should ingest data from thousands of units, detect anomalies, and alert maintenance teams proactively.

Type · past-experience

Tell me about a time you had to work with a complex legacy system at Terna. What were the biggest challenges, and how did you approach understanding and improving it?

+ many more questions, signals, and worked examples

Unlock the Terna rubric, free

Terna Interview Question Bank

A sample from our database, grouped by round. Sign up to see the full set.

9 of 12 questions shown

Recruiter Screen

1
Type · motivation
Terna is a leader in energy infrastructure. What interests you specifically about contributing to the energy sector, and how do you see your software engineering skills making an impact here?

Coding Screen

2
Type · algorithmic
Imagine Terna needs to optimize the real-time distribution of electricity across a complex grid to minimize losses and prevent overloads. Given a list of grid segments, their current load, and their capacity, design an algorithm to identify the most critical segments that, if overloaded, would cause cascading failures. You can assume a simplified graph representation of the grid.
3
Type · algorithmic
Terna monitors thousands of energy meters. You receive a stream of meter readings, each with a timestamp and a value. Design a data structure and algorithm to efficiently calculate the average reading for any given 1-hour window in the past 24 hours, with minimal latency.
+ 1 more questions in this round (sign up to unlock)

System Design

4
Type · system-design
Design a system for Terna to monitor and predict potential faults in a large network of distributed energy storage units (e.g., batteries). The system should ingest data from thousands of units, detect anomalies, and alert maintenance teams proactively.
5
Type · system-design
Terna is developing a platform to allow customers to dynamically manage their energy consumption based on real-time pricing and grid load. Design the backend services for this platform, considering aspects like user profiles, device integration, pricing engine, and command execution.
+ 1 more questions in this round (sign up to unlock)

Onsite Coding

6
Type · coding
Implement a function that simulates the cascading failure of a power grid. Given a grid represented as an adjacency list and an initial fault point, the function should return the set of nodes that go offline. A node goes offline if its load exceeds its capacity due to upstream failures. Assume each node has a capacity and a current load.
7
Type · coding
Terna needs to process large volumes of sensor data from substations. Implement a function that efficiently filters and aggregates this data. Given a list of sensor readings (each with a timestamp, sensor ID, and value), write a function to return the average value for each sensor ID within a specified time range, handling potential duplicate readings.

Behavioral / Leadership

8
Type · past-experience
Tell me about a time you had to work with a complex legacy system at Terna. What were the biggest challenges, and how did you approach understanding and improving it?
9
Type · past-experience
Describe a situation where you disagreed with a technical decision made by your team or lead at Terna. How did you handle the disagreement, and what was the outcome?
+ 1 more questions in this round (sign up to unlock)

Unlock all 12 Terna questions, free

No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.

Unlock all 12 Terna questions

Interview tracks at Terna

How Terna's DNA translates across functions. Pick your role.

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Compare Terna with similar employers

Same DNA, different bar. Browse the closest companies in our database and see how their loops differ.

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Practice Terna interviews end-to-end

Terna Mock Interview

Run a live mock interview with our AI interviewer using Terna-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.

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STAR Stories for Terna Behavioral Rounds

Build a Story Bank of your past wins, mapped to the leadership signals Terna interviewers grade on. Reuse them across every behavioral round.

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Terna Interview Prep Hub

The frameworks behind every Terna 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 Terna 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 Terna interview questions shows.

A strong answer shows: Ability to translate a practical problem into an algorithmic one.; Correct application of graph traversal or related algorithms.; Consideration of edge cases like isolated grid segments or full capacity..

A strong answer shows: Scalable data ingestion and processing architecture.; Robust anomaly detection mechanisms.; Effective alerting and notification strategy.; Consideration of data storage and retrieval..

Frequently asked questions

How long does the Terna 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 Terna?

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 Terna?

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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