Interview guides · DTE Energy

DTE Energy Software Engineer Interview Guide

DTE Energy Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

As a Software Engineer at DTE Energy, you play a vital role in powering the energy infrastructure for millions of residential and commercial customers across Michigan. Software engineering at a major diversified energy company is distinct from typical SaaS technology environments. You sit at the exact nexus of modern digital software development, enterprise cloud platforms, and critical operational technology (OT) supporting grid reliability, gas distribution pipelines, and clean energy transition initiatives. Your work directly impacts real-world physical systems, grid monitoring applications, internal enterprise platforms, asset management systems, and customer-facing web and mobile applications.

This guide is scoped to a Software Engineer candidate at DTE Energy.

Focus areas

Behavioral Interviewing (STAR method)
Structured Response Frameworks
Competency-Based Interview Questions

The DTE Energy interview process

DTE Energy candidates report 5 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Online Application

Candidates submit their applications online for the Software Engineer position.

What to demonstrate

Candidates submit their applications online for the Software Engineer position
Depth in Behavioral Interviewing (STAR method)

How to prepare

Answer aloud and timed: Describe a situation where you had to show initiative without being asked. What was the scenario, and what was the final outcome?
Answer aloud and timed: Give an example of a time when you were confronted with a complex project problem. How did you break it down and solve it?

Pre-Hire Assessment

Selected candidates complete a timed assessment evaluating situational judgment and problem-solving skills.

What to demonstrate

Selected candidates complete a timed assessment evaluating situational judgment and problem-solving skills
Depth in Behavioral Interviewing (STAR method)

How to prepare

Answer aloud and timed: Describe a time when you had to manage competing priorities under a tight deadline. How did you determine what to focus on?
Answer aloud and timed: Can you share an example of a time when you identified an inefficiency in a process or application and took steps to remedy it?

Initial Screening Call

A conversation with HR or a recruiting consultant covering background, salary, and role alignment.

What to demonstrate

A conversation with HR or a recruiting consultant covering background, salary, and role alignment
Depth in Behavioral Interviewing (STAR method)

How to prepare

Be able to walk your CV end to end in two minutes, and say why this company specifically.
Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Panel Interview

A formal interview conducted virtually or on-site with a panel of 2-4 members including managers and peers.

What to demonstrate

A formal interview conducted virtually or on-site with a panel of 2-4 members including managers and peers
Depth in Behavioral Interviewing (STAR method)

How to prepare

Answer aloud and timed: Give an example of how you explained a complex technical concept or issue to a non-technical stakeholder or partner.
Answer aloud and timed: Tell us about a time when you worked on a project team where a peer was not pulling their weight. How did you handle it?

Calibration Session

Panel members grade responses on a standard rubric and submit their final recommendation to HR.

What to demonstrate

Panel members grade responses on a standard rubric and submit their final recommendation to HR
Depth in Behavioral Interviewing (STAR method)

How to prepare

Answer aloud and timed: Describe a situation where you had to adjust your communication style to successfully collaborate with a cross-functional group.
Answer aloud and timed: Walk us through a recent software application or feature you engineered from scratch. What was your specific personal role?

Where candidates lose points

Structure every behavioral response explicitly

Literally speak the framework aloud during your panel interview (e.g., "The situation was...", "My specific task was...", "The actions I personally took included...", "The final result was..."). This helps interviewers fill out their evaluation forms quickly.

Prepare 6 to 8 versatile STAR stories

Draft stories from past jobs or academic projects that cover common competencies: technical problem solving, dealing with project failure, resolving peer disagreements, showing initiative, and managing tight deadlines.

Research DTE Energy's business units

Familiarize yourself with the distinction between DTE Electric and DTE Gas, as well as broader company goals like grid modernization, clean energy transition, and operational reliability. Mentioning these demonstrates real interest.

Review your resume thoroughly before the panel interview

Panel members will ask deep-dive questions about specific projects, tools, and technical accomplishments listed on your application.

Questions & practice

Find overlapping job attempts and peak concurrency from lease records

Medium · sweep line · intervals · leases

A day of job_run history yields about 50,000,000 attempt records: (job_run_id, job_type, attempt, started_at, finished_at which is NULL when the worker died, lease_expires_at). Leases expire on a clock, so a job that outran its lease ran twice. Produce (a) every job_run_id whose attempts overlapped in wall-clock time and (b) the peak number of simultaneously running attempts per job_type with the minute it occurred. Target O(n log n). State how you treat a NULL finished_at and what clock skew does to your answer.

Approach

Define the interval before sorting anything: an attempt occupies [started_at, COALESCE(finished_at, lease_expires_at)). finished_at is observed and lease_expires_at is only a promise, so every attempt without a finish contributes an estimate and the whole result is a lower bound on overlap rather than an exact count.
For peak concurrency, sweep: emit 2n endpoints, sort by (timestamp, kind) with ends ordered before starts at equal timestamps, then walk the sequence maintaining a counter per job_type and record each type's maximum with its timestamp. O(n log n) dominated by the sort, O(n) space, or O(1) extra if the sort is external and the walk streams.
For overlap detection, do not compare attempts pairwise. A single global sort by (job_run_id, started_at) gives both the grouping and the order; within a group, keep the maximum end seen so far and report an overlap exactly when the next start is less than that running maximum, which is one linear pass after the sort.
Half-open intervals matter and are easy to get wrong: with closed intervals an attempt ending at the same millisecond another begins reads as concurrency two, and across 50,000,000 records that artefact swamps the real signal.

Follow-up

A handler is not idempotent and you have found 400 overlapping jobs. Which of them actually caused damage, and what would you query to find out?
Peak concurrency for one job_type is 4 against a configured cap of 4. Is the cap working, or is the data hiding attempts that never started?

Track a rolling failure rate per destination for circuit decisions

Easy · sliding window · ring buffer · circuit breaker

The egress service delivers about 1,500 webhooks per second across roughly 40,000 destinations, each call bounded by a 10 second timeout. Maintain, per destination, the failure rate over the trailing 60 seconds so a caller can ask before dispatch whether the circuit should open. Attempts arrive as (destination_id, finished_at_ms, outcome). Requirement: amortised O(1) per attempt, with total memory bounded by the destination count rather than by traffic. Give the structure, its exact memory, and the rule that stops a destination with three attempts from opening a circuit.

Approach

Name the exact-deque version and then reject it as the default. Holding timestamps and advancing a tail pointer past anything older than now minus 60 seconds is a correct two-pointer window at amortised O(1) per attempt, but its memory tracks in-window traffic, so one destination in a retry storm holds hundreds of thousands of entries while thousands of quiet destinations hold none.
Use a ring of 60 one-second buckets per destination, each bucket a pair of counters for attempts and failures. On an attempt, advance the ring by the elapsed whole seconds, zeroing at most min(elapsed, 60) buckets, then increment the head. That is amortised O(1) with a fixed footprint per destination.
State the footprint: 60 buckets times two 4-byte counters is 480 bytes of payload per destination, so 40,000 destinations is roughly 20 to 25 MB with per-entry overhead, bounded by the catalogue rather than by the rate. The cost is granularity, since the oldest bucket ages out in whole seconds, which is far tighter than the decision needs.
Require a minimum sample before the circuit may open. A destination with three attempts and three failures reads as 100 percent and is not evidence; a floor of roughly 20 attempts in the window makes the ratio meaningful, and below that floor use a run of consecutive failures as the trigger instead.

Follow-up

The fleet is 30 instances and each sees roughly a thirtieth of a destination's traffic. Where does the rate actually live, and what does a per-instance answer get wrong?
A destination answers in 9.5 seconds and succeeds. It is not failing but it is consuming your per-destination concurrency. What signal should open the circuit here?

Diff a projection against the primary without per-row point reads

Hard · reconciliation · range hashing · throttling

The listing projection has drifted and some rows show a stale version. The primary holds 40,000,000 resource rows across 12,000 tenants while serving 1,200 writes and 14,000 reads per second. The obvious repair, reading each resource row and comparing its version against the projection, is correct and would eventually finish. Explain precisely why it is unacceptable here, then give a diff that finds the differing rows, state its complexity, and make it safe to run against a live primary. Replication lag is usually under 100 ms and is not bounded.

Approach

Quantify the naive cost rather than calling it slow: 40,000,000 point reads at even 0.5 ms each is over five hours serialised, and the only lever is concurrency, which is exactly what you cannot spend. The primary's pool is sized for the write path, and 40,000,000 random reads evict the buffer cache that sustains the 85 percent cache hit rate, so the audit degrades the system it is auditing.
Replace random access with one ordered pass per side. Both sides can be read in (tenant_id, resource_id) order, which is a sequential scan on each and a merge join in O(n) time and O(1) memory. For a dense diff that is the whole answer, and it reads the primary once instead of 40,000,000 times.
For the expected sparse case, compare range hashes instead of rows: partition the key space, compute per range an order-independent aggregate over hash(resource_id, version), compare aggregates, and descend only into ranges that differ. With d differing rows and branching factor B, at most d ranges mismatch per level, so the drill-down examines O(d log_B(n/d)) ranges and reads full rows only in mismatching leaves.
Aggregate with a sum modulo 2^64 or a multiset hash, never XOR. XOR is order-independent but self-cancelling, so two rows wrong in the same way, or a row duplicated on one side, leave the range aggregate matching and the range is declared clean.

Follow-up

The diff reports 900 stale rows. How do you decide between patching those rows and rebuilding the projection from resource_revision?
Same job, but the projection lives in a search index that cannot be scanned in key order. What changes?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
How do you verify the backfill actually finished, given rows are still being inserted while it runs?

Hold a per-tenant active cap against concurrent creates

Hard · write skew · isolation levels · constraints

A tenant on the standard plan may hold at most 50 resources with status='active'. The create handler runs SELECT count(*) FROM resource WHERE tenant_id = $1 AND status = 'active', compares to 50, then inserts. Two creates arrive 3 ms apart on different instances and the tenant lands at 51. Name the anomaly, say whether PostgreSQL 16 READ COMMITTED or REPEATABLE READ prevents it and why, then give an implementation that holds the cap at READ COMMITTED with the exact statements. Finally, say what changes when the cap is 'at most one running export per tenant' on job_run.

Approach

Name it: write skew. The two transactions read an overlapping set and write disjoint rows, so there is no row-level conflict for the engine to detect and each commit is individually legal.
Rule out the levels precisely. READ COMMITTED takes a fresh snapshot per statement and takes no lock on the counted rows, so both see 49. PostgreSQL's REPEATABLE READ is snapshot isolation: it removes non-repeatable reads and phantoms within the snapshot but still admits write skew, because the anomaly is not a re-read of a changed row, it is a read of a set that a concurrent transaction invalidates. Only SERIALIZABLE closes it, by tracking the read dependency and aborting one transaction with SQLSTATE 40001 — a guarantee that exists only if the application re-runs the whole transaction from the read.
Convert the set predicate into a single-row conflict: keep tenant.active_resource_count and run UPDATE tenant SET active_resource_count = active_resource_count + 1 WHERE tenant_id = $1 AND active_resource_count < 50 in the same transaction as the INSERT. Zero affected rows is the cap, returned as 409. The row lock serialises the decision at any isolation level, and contention is bounded to one tenant's row — which is also the fair-scheduling unit, unlike a global counter that would convoy every tenant behind one row.
State the cost you just took on: a counter is a second source of truth that can drift, so every path that changes status must adjust it inside the same transaction, and a periodic reconciliation has to exist, with resource_revision as the authority for what the count should have been.

Follow-up

A resource moves from archived back to active. Which statements change, and what breaks if the counter update and the status change land in different transactions?
The cap becomes plan-dependent and a plan can change mid-month. Where does the number 50 live, and who reads it?

Give an example of how you explained a complex technical concept or issue to a non-technical stakeholder or pa

Medium · Teamwork & Conflict Resolution

Give an example of how you explained a complex technical concept or issue to a non-technical stakeholder or partner.

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

Describe a situation where you had to adjust your communication style to successfully collaborate with a cross

Medium · Teamwork & Conflict Resolution

Describe a situation where you had to adjust your communication style to successfully collaborate with a cross-functional group.

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

Walk us through a recent software application or feature you engineered from scratch. What was your specific p

Medium · Technical Execution & Project Architectu

Walk us through a recent software application or feature you engineered from scratch. What was your specific personal role?

Approach

Fix the scope first: who calls this, how often, and what they do when it fails.
Name the read and write paths separately; they rarely have the same bottleneck.
Choose a partition key and say what query it makes expensive.
State the consistency you need, and where you are willing to be stale.

Follow-up

What breaks first when traffic grows ten times?
How does this behave when that dependency is down for an hour?

How do you ensure code quality, maintainability, and test coverage when building mission-critical services?

Medium · Technical Execution & Project Architectu

Approach

Fix the scope first: who calls this, how often, and what they do when it fails.
Name the read and write paths separately; they rarely have the same bottleneck.
Choose a partition key and say what query it makes expensive.
State the consistency you need, and where you are willing to be stale.

Follow-up

What breaks first when traffic grows ten times?
How does this behave when that dependency is down for an hour?

Why do you want to work as a Software Engineer specifically at DTE Energy?

Medium · Alignment, Safety & Company Context

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

What do you know about our current technology initiatives, energy platforms, or gas and electric utility opera

Medium · Alignment, Safety & Company Context

What do you know about our current technology initiatives, energy platforms, or gas and electric utility operations?

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

How do you incorporate safety, security, and risk mitigation principles into your software development workflo

Medium · Alignment, Safety & Company Context

How do you incorporate safety, security, and risk mitigation principles into your software development workflow?

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

Describe yourself in three professional words and explain why you chose them.

Medium · Alignment, Safety & Company Context

Approach

Clarify what is being asked and what a complete answer contains.
State your assumptions explicitly before working the problem.
Say what you would check first and why it is the highest-information step.
Work from the requirement backwards to the design.

Follow-up

What assumption would you test first?
How would you know your answer was wrong?

Tell us about a time you had to debug a difficult production defect or system outage. What was your root cause

Medium · Technical Execution & Project Architectu

Tell us about a time you had to debug a difficult production defect or system outage. What was your root cause analysis process?

Approach

Establish what changed and when, before forming any theory.
Pick a bisection that eliminates candidates whichever way it turns out.
Check the instrumentation before believing the symptom.
Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

What would you look at first, and what would it rule out?
How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics DTE Energy candidates report.

Day 1 — Map the DTE Energy loop

Write out the reported sequence: Online Application, Pre-Hire Assessment, Initial Screening Call, Panel Interview, Calibration Session.
For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 5 reported rounds, with the weakest marked.

Day 2 — Work Behavioral Interviewing (STAR method)

Spend the session on Behavioral Interviewing (STAR method), which DTE Energy candidates report being tested on.
Write one worked example in Behavioral Interviewing (STAR method) and time yourself on it.

Deliverable: One timed worked example in Behavioral Interviewing (STAR method).

Day 3 — Work Structured Response Frameworks

Spend the session on Structured Response Frameworks, which DTE Energy candidates report being tested on.
Write one worked example in Structured Response Frameworks and time yourself on it.

Deliverable: One timed worked example in Structured Response Frameworks.

Day 4 — Work Competency-Based Interview Questions

Spend the session on Competency-Based Interview Questions, which DTE Energy candidates report being tested on.
Write one worked example in Competency-Based Interview Questions and time yourself on it.

Deliverable: One timed worked example in Competency-Based Interview Questions.

Day 5 — Answer out loud: Behavioral & STAR Competencies

Answer aloud, timed: Describe a situation where you had to show initiative without being asked. What was the scenario, and what was the final outcome?
Answer aloud, timed: Give an example of a time when you were confronted with a complex project problem. How did you break it down and solve it?

Deliverable: Spoken answers to 2 reported Behavioral & STAR Competencies question(s), under time.

Day 6 — Answer out loud: Teamwork & Conflict Resolution

Answer aloud, timed: Describe a situation where a team member did not agree with your technical approach. How did you handle the disagreement?
Answer aloud, timed: Give an example of how you explained a complex technical concept or issue to a non-technical stakeholder or partner.

Deliverable: Spoken answers to 2 reported Teamwork & Conflict Resolution question(s), under time.

Day 7 — Answer out loud: Technical Execution & Project Architecture

Answer aloud, timed: Walk us through a recent software application or feature you engineered from scratch. What was your specific personal role?
Answer aloud, timed: How do you ensure code quality, maintainability, and test coverage when building mission-critical services?

Deliverable: Spoken answers to 2 reported Technical Execution & Project Architecture question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Describe a situation where you had to show initiative without being asked. What was the scenario, and what was

Medium · Behavioral & STAR Competencies

Describe a situation where you had to show initiative without being asked. What was the scenario, and what was the final outcome?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Give an example of a time when you were confronted with a complex project problem. How did you break it down a

Medium · Behavioral & STAR Competencies

Give an example of a time when you were confronted with a complex project problem. How did you break it down and solve it?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe a time when you had to manage competing priorities under a tight deadline. How did you determine what

Medium · Behavioral & STAR Competencies

Describe a time when you had to manage competing priorities under a tight deadline. How did you determine what to focus on?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Can you share an example of a time when you identified an inefficiency in a process or application and took st

Medium · Behavioral & STAR Competencies

Can you share an example of a time when you identified an inefficiency in a process or application and took steps to remedy it?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe a situation where you made a mistake on a technical project. How did you address it, and what did you

Medium · Behavioral & STAR Competencies

Describe a situation where you made a mistake on a technical project. How did you address it, and what did you learn?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe a situation where a team member did not agree with your technical approach. How did you handle the di

Medium · Teamwork & Conflict Resolution

Describe a situation where a team member did not agree with your technical approach. How did you handle the disagreement?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Tell us about a time when you worked on a project team where a peer was not pulling their weight. How did you

Medium · Teamwork & Conflict Resolution

Tell us about a time when you worked on a project team where a peer was not pulling their weight. How did you handle it?

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?

Describe your experience integrating software applications with existing legacy databases, APIs, or operationa

Medium · Technical Execution & Project Architectu

Describe your experience integrating software applications with existing legacy databases, APIs, or operational telemetry platforms.

Approach

Pick a story where you made the decision, not one where you watched it.
State the situation in two sentences and spend the rest on the reasoning.
Give the blast radius: what could have broken, and what you measured.
Name the disagreement and how you resolved it with evidence.

Follow-up

What would you do differently if you ran that again?
How did you know your change caused the improvement?