How to Pass the Iberdrola Software Engineer Interview in 2026

The Iberdrola DNA (TL;DR)

Iberdrola seeks candidates demonstrating strong analytical skills, a commitment to sustainability, and a proactive approach to innovation in the energy sector. They value adaptability, teamwork, and a global mindset, particularly for roles involving renewable energy projects and grid modernization.

Interviews inJava Python

The Iberdrola Interview Loop

Your onsite loop will typically consist of 4 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, debugging, 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 Iberdrola interview outcomes, avoid these common traps:

Not handling the query period boundaries precisely (e.g., including/excluding start/end times).
Inefficiently recalculating the mean and standard deviation for every new data point, leading to O(n^2) complexity.
Failing to consider memory constraints for potentially very large streams of data.
Incorrectly calculating Manhattan distance or applying the overlap constraint.

Test Yourself: Real Iberdrola Questions

Three real prompts pulled from our database.

Type · Scalability

Design a system to monitor and control millions of IoT devices (smart meters, grid sensors, EV chargers) connected to Iberdrola's network. The system needs to handle high-volume data ingestion, device state management, and command execution with low latency.

Type · Data Structures

Design a data structure that can efficiently store and query the real-time power output (in MW) of thousands of solar panels across multiple solar farms. The structure should support two main operations: 1. `update_output(panel_id, power_mw)`: Updates the power output for a specific panel. 2. `get_farm_total_output(farm_id)`: Returns the sum of power output for all panels in a given farm. Assume farm IDs and panel IDs are provided.

Type · Debugging

A critical service responsible for processing energy meter readings is experiencing intermittent failures. Below is a simplified (and potentially buggy) Python code snippet. Identify potential bugs, explain the root cause, and provide a corrected version. The service is supposed to calculate the average consumption per day, but sometimes returns incorrect averages or crashes.

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Iberdrola Interview Question Bank

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

9 of 14 questions shown

Recruiter Screen

1
Type · Motivation
Why are you interested in joining Iberdrola, and what specifically about our work in the energy sector excites you as a software engineer?

Coding Screen

2
Type · Algorithmic
Given a stream of real-time energy consumption data from smart meters (represented as tuples of (timestamp, meter_id, consumption_kwh)), design an algorithm to detect anomalous consumption patterns for each meter within a rolling 24-hour window. An anomaly is defined as consumption deviating by more than 3 standard deviations from the mean consumption for that meter during that window.
3
Type · Algorithmic
Iberdrola operates a vast network of renewable energy sources (solar farms, wind turbines). You are given a 2D grid representing a geographical area, where 'W' denotes a potential wind turbine location, 'S' a solar farm location, and '.' an empty space. Write a function to find the maximum number of non-overlapping renewable energy installations (wind turbines and solar farms) that can be placed, subject to the constraint that no two installations can be within a Manhattan distance of 5 units from each other.
+ 1 more questions in this round (sign up to unlock)

System Design

4
Type · Distributed Systems
Design a system to predict and manage potential grid overload events across Iberdrola's European network. The system should ingest data from various sources (weather forecasts, historical demand, real-time consumption, renewable energy generation) and predict high-risk periods, potentially triggering automated load balancing actions.
5
Type · Architecture
Iberdrola is developing a new customer portal for managing energy accounts, viewing consumption, and interacting with smart home devices. Design the backend architecture for this portal, considering scalability, security, and the integration of various services (e.g., billing, device management, analytics).
+ 1 more questions in this round (sign up to unlock)

Onsite Coding

6
Type · Algorithmic
You are given a list of time intervals, each representing a period when a specific wind turbine was operational (e.g., `[(start_time, end_time, turbine_id), ...]`). Write a function to calculate the total uptime for each turbine within a given query period `(query_start, query_end)`. Ensure your solution correctly handles overlapping intervals and edge cases.
7
Type · Debugging
A critical service responsible for processing energy meter readings is experiencing intermittent failures. Below is a simplified (and potentially buggy) Python code snippet. Identify potential bugs, explain the root cause, and provide a corrected version. The service is supposed to calculate the average consumption per day, but sometimes returns incorrect averages or crashes.
+ 2 more questions in this round (sign up to unlock)

Behavioral / Leadership

8
Type · Conflict Resolution
Iberdrola often balances the immediate need for grid stability with the long-term goal of integrating intermittent renewable sources. Describe a time you advocated for a specific architectural trade-off in a system where performance requirements conflicted with sustainability or scalability goals. How did you reconcile these competing technical priorities with your team?
9
Type · Ownership
Describe a situation where you had to debug a complex and critical issue in a system you weren't initially familiar with. What steps did you take to understand the system, diagnose the problem, and implement a fix? How did you ensure the fix was robust?
+ 1 more questions in this round (sign up to unlock)