REP Practice Test

The REP credential from the Association of Energy Engineers is aimed at people who plan, finance and evaluate renewable energy projects. This page gives you the exam format as AEE states it, fees and retake rules, worked practice questions with explanations, and free practice sets by topic. The exam is 4 hours and open book. Practice with the free Certified Renewable Energy Professional practice test on PracticeTestGeeks (9 questions with answer explanations).

Free Certified Renewable Energy Professional Study Tools

Interactive Certified Renewable Energy Professional resources on PracticeTestGeeks, free to start:

• REP Renewable Energy Technologies & Applications — 9 questions with answer explanations
• Certified Renewable Energy Professional flashcards — review key terms and concepts card by card
• Certified Renewable Energy Professional study guide — topic-by-topic overview of what the exam covers
• Certified Renewable Energy Professional cheat sheet — one-page printable summary for last-minute review

REP Exam at a Glance

What the REP is and how it works

According to Association of Energy Engineers, “All exams are multiple choice. The number of questions on the exam varies per program.”^[3]

The Certified Renewable Energy Professional (REP) credential is awarded by the Association of Energy Engineers (AEE). The exam is multiple choice. AEE says the number of questions varies per program, and the questions are weighted by the Body of Knowledge, so check the official study guide for the current outline.

You can sit the exam in person as part of a training program, or online through ProctorU. The listed in-person session is in Atlanta, GA, with training before the exam on September 23, 2027. The exam is 4 hours and open book, which means speed at finding and applying reference material matters as much as recall.

The application and exam fee is $400 in the US and is nonrefundable. AEE encourages you to submit the application about 4 weeks before the exam, because it needs that time to process it. Your official score letter is sent by email within 30 days. AEE asks that you not contact it or the training partner before then, and scores are not posted on the AEE website.

If you need another attempt, the retest fee is $200 in the US. You must wait at least 60 days between attempts. You can book as soon as your score letter arrives, as long as the new date is at least 60 days after the previous exam.

The certification is valid for 3 years. Renewal costs $300 every 3 years and requires 10 renewal credits. Eligibility requirements and fees outside the US can differ, so confirm both on the AEE page for becoming a REP before you apply.

Worked examples: how to reason through REP questions

These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.

Example 1

Question: In US project finance, a 'tax equity flip' structure refers to the point at which:

1. The project switches from fixed-price to merchant electricity sales
2. The tax equity investor's ownership percentage decreases after achieving its target return
3. The project refinances its construction loan with a permanent term loan
4. The developer sells its equity stake to a long-term infrastructure fund

Answer: B. The tax equity investor's ownership percentage decreases after achieving its target return

Explanation:

B is correct. In a tax equity partnership, the investor receives most of the tax benefits early. Once it reaches its target return, its ownership share steps down and the developer's share rises. That step-down is the flip.

A describes a change in how power is sold, which is a revenue strategy and not an ownership change. C describes refinancing debt, which changes the lender and not the equity split. D describes the developer selling out, but in a flip the developer stays and gains a larger share.

Rule to remember: a flip is about who owns the cash and tax benefits, and it is triggered by the investor hitting its return target.

Example 2

Question: A developer is comparing a 30-year project life to a 25-year project life for the same wind farm. Assuming equal annual cash flows, the 30-year scenario will have a:

1. Lower IRR and lower NPV
2. Higher IRR and lower NPV
3. Lower IRR but potentially higher NPV depending on the discount rate
4. Higher IRR and higher NPV in all cases

Answer: C. Lower IRR but potentially higher NPV depending on the discount rate

Explanation:

C is correct. Extra years of cash flow add value, so NPV can rise, but only if those later cash flows are still worth something after discounting. A high discount rate can shrink that gain to almost nothing. IRR is the rate that sets NPV to zero, and when early returns are strong, added late cash flows pull it down slightly.

A is wrong because longer life does not reduce NPV when the added flows are positive. B is wrong because it reverses the usual relationship. D is wrong because the words in all cases ignore the discount rate and the pull on IRR.

Rule to remember: NPV depends on the discount rate, and IRR does not reward long tails the way NPV can.

Example 3

Question: Which type of biomass combustion system is best suited for fuels with widely varying particle sizes and moisture content?

1. Pulverized fuel burner
2. Stoker/grate-fired boiler
3. Entrained flow gasifier
4. Pellet-only automated system

Answer: B. Stoker/grate-fired boiler

Explanation:

B is correct. A stoker or grate-fired boiler moves fuel across a grate and burns it in a bed, so it tolerates uneven particle sizes and wetter fuel without much preparation.

A is wrong because pulverized fuel burners need fuel ground to a fine, consistent size and dry enough to burn in suspension. C is wrong because entrained flow gasifiers also require finely sized, uniform feed. D is wrong because pellet-only systems depend on a standardized fuel, so they cannot take varied material.

Rule to remember: the more variable the fuel, the more you want a bed or grate system. The more uniform the fuel, the more suspension or pellet systems make sense.

How to use these practice tests

Start by reading the official REP study guide from AEE so you know what the Body of Knowledge weights most. Because the exam is open book, decide early which reference material you will bring and how you will find things in it.

Then work through our practice sets by topic. Cover the technology areas, such as solar energy systems, wind power technologies, geothermal and hydropower and storage and grids. Add the business side with project finance and economics and policy.

After each set, read the explanation for every question, including the ones you got right, and write down the rule behind each miss. Look those rules up in your reference material so you practise finding them, not only remembering them.

Near test day, take a full practice test under timed conditions, then return to the sets where you missed the most. Our questions are written by us and are not real exam questions, so use them to find weak areas and not to predict what you will see.

Sources & last verified

1. Association of Energy Engineers — time limit (official source). “The REP Certification exam is a four-hour open book exam.” Verified Oct 22, 2026.
2. Association of Energy Engineers — exam fee, retake fee, renewal, delivery (official source). “Certification Application and Examination Fees: $400 Application and examination fees are nonrefundable.” Verified Oct 22, 2026.
3. Association of Energy Engineers — number of questions, retake policy, validity, score release (official source). “All exams are multiple choice. The number of questions on the exam varies per program.” Verified Oct 22, 2026 · source checked Oct 18, 2026.
4. Association of Energy Engineers — registration deadline (official source). “Attendees are encouraged to complete a certification application 4 weeks prior to taking the exam.” Verified Oct 22, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.