Het energieverbruik bepaalt het bedrag op de jaarafrekening.

Because both energieverbruik and bedrag are het-words in Dutch, meaning they take the definite article het rather than de.

A useful thing to know is that in Dutch compound nouns, the last part usually determines the gender:

• energieverbruik ends in verbruik, and verbruik is a het-word
• bedrag is also a het-word

So:

• het energieverbruik
• het bedrag

By contrast, jaarafrekening ends in afrekening, which is a de-word, so you get de jaarafrekening.

Yes. Dutch very often forms long compound nouns by writing them as one word.

So:

• energie
  • verbruik = energieverbruik

This is completely normal in Dutch. English often uses separate words where Dutch prefers one compound word.

Other similar examples:

• waterverbruik = water consumption
• stroomverbruik = electricity usage
• energiebedrijf = energy company

Because the subject is singular: het energieverbruik.

The verb is bepalen = to determine. In the present tense:

• ik bepaal
• jij bepaalt
• hij/zij/het bepaalt
• wij/jullie/zij bepalen

Since het energieverbruik is grammatically singular, Dutch uses the third-person singular form:

• Het energieverbruik bepaalt ...

This is the normal word order for a Dutch main clause:

subject + finite verb + rest

So:

• Het energieverbruik = subject
• bepaalt = finite verb
• het bedrag op de jaarafrekening = rest of the sentence

Dutch is a V2 language, which means the finite verb usually comes in the second position in a main clause.

In this sentence, the subject is in first position, so the verb naturally comes next.

Op de jaarafrekening means something like on the annual bill/statement.

Here it tells you where that amount appears or where the amount is shown.

So the structure is roughly:

• het bedrag = the amount
• op de jaarafrekening = on the annual statement/bill

In other words, it is the amount listed on the yearly bill.

Because op is the most natural preposition when talking about information shown on a bill, invoice, form, or statement.

Dutch often uses op in this kind of context:

• op de rekening
• op de factuur
• op het formulier

Using in would suggest something more like inside the contents of a document, and van would mean of/from, which changes the meaning.

So in this sentence, op de jaarafrekening is the idiomatic choice.

Because afrekening is a de-word, and in a compound noun the final part usually determines the article.

• jaar
  • afrekening = jaarafrekening
• the head word is afrekening
• afrekening takes de
• so: de jaarafrekening

This is a very useful pattern for Dutch learners:

• het energieverbruik because verbruik is a het-word
• de jaarafrekening because afrekening is a de-word

Bedrag means amount or sum of money.

In this sentence, het bedrag is the amount that appears on the annual bill.

Compare:

• bedrag = amount, sum
• prijs = price
• kosten = costs/expenses

So bedrag fits well here because the sentence is talking about the final monetary figure on the bill, not just the general idea of price.

Yes, that is a very natural translation here.

bepalen often means:

• to determine
• to decide
• to define

In this sentence, determines works well because the energy usage is what decides the final amount on the annual bill.

So:

• Het energieverbruik bepaalt het bedrag ... = The energy consumption determines the amount ...

Yes, but then the sentence structure has to follow Dutch V2 word order.

For example, if you move op de jaarafrekening to the front, the verb must still stay in second position:

• Op de jaarafrekening bepaalt het energieverbruik het bedrag.

That is grammatically correct, but it sounds more marked or emphatic than the original.

The original sentence is the most neutral:

• Het energieverbruik bepaalt het bedrag op de jaarafrekening.

Yes, it is an active sentence:

• het energieverbruik does the determining
• het bedrag is what gets determined

A passive version would be:

• Het bedrag op de jaarafrekening wordt bepaald door het energieverbruik.

That means the same thing, but the focus shifts to het bedrag rather than het energieverbruik.

Both are correct; the active version is shorter and more direct.