Le médiateur national de l’énergie vérifie le trop-perçu.

It is built in a very typical French way:

• le médiateur = the mediator / ombudsman
• national = national
• de l’énergie = of energy

So French puts the main noun first, then the adjective, then the de-phrase:

• médiateur
  • national
    • de l’énergie

That is why the order is not like English the national energy mediator, even though that is how English would usually express it.

In this sentence, national describes médiateur, not énergie.

Although médiateur looks a lot like English mediator, in this context it often refers to an official person or body that helps resolve disputes between citizens and organizations.

So here it is closer to:

• mediator
• ombudsman
• dispute-resolution authority

The exact English equivalent depends on context, but the French word often has this official administrative meaning.

Because énergie is:

• feminine singular
• and begins with a vowel sound

Normally you would have:

• de la
  • feminine singular noun

But before a vowel, French uses elision:

• de la énergie → de l’énergie

This is the same pattern as:

• la école → l’école
• de la eau → de l’eau

So de l’énergie is simply the correct contracted form.

Because it agrees with médiateur, which is masculine singular.

• le médiateur = masculine singular
• so the adjective is national

If the noun were feminine, it would change:

• la médiatrice nationale

French adjectives must agree in gender and number with the noun they describe.

Vérifie is the present indicative, third-person singular form of the verb vérifier.

So:

• je vérifie = I check
• tu vérifies = you check
• il / elle / on vérifie = he / she / one checks

Here the subject is Le médiateur national de l’énergie, which is singular, so the verb is vérifie.

Because trop-perçu is being used as a noun here, and it is treated as masculine singular.

So:

• le trop-perçu = the overpayment / the excess amount received

It is the direct object of vérifie:

• vérifie quoi ? → le trop-perçu

French often uses an article where English might use one or might not, depending on context.

Yes, in this sentence it functions as a noun.

It is a fixed compound term used especially in administrative, legal, or financial French. It refers to money that was received in excess, such as an overpayment.

Even though it comes from the idea of too much received, in modern usage you can simply treat it as a vocabulary item:

• un trop-perçu
• le trop-perçu

So for a learner, the safest approach is: memorize it as a compound masculine noun commonly used in formal contexts.

It is hyphenated because it is a set compound expression.

French often uses hyphens in established compound nouns, especially in administrative or technical vocabulary. The hyphen shows that the two parts form one unit of meaning.

So here:

• trop
  • perçu → trop-perçu

You should learn the spelling as a fixed form.

Perçu comes from the verb percevoir and is the past participle form.

In everyday learning terms, you do not need to analyze the whole expression every time, but it can help to know that:

• percevoir = to receive / collect
• perçu = received / collected

So trop-perçu literally suggests something like too much received, which explains why the noun means an overpayment or excess amount received.

A simple pronunciation guide:

• vérifie ≈ veh-ree-fee
  • the final e is not pronounced
• trop-perçu ≈ troh-pehr-syoo
  • the ç gives an s sound
  • the u in çu is the French u, which does not exist exactly in English

Roughly, the whole sentence sounds like:

luh may-dyah-tuhr nah-syo-nal duh lay-nayr-zhee vay-ree-fee luh troh-pehr-syoo

That is only an approximation, but it can help at first.

The accents matter for both spelling and pronunciation.

• é in énergie and vérifie signals a clear ay-type sound
• ç in perçu makes the c sound like s, not k

So:

• énergie is not spelled energie
• perçu is not the same as percu

In French, accents are a normal part of the written word, not optional decoration.