Ο ενεργειακός επιθεωρητής ελέγχει τον ηλιακό θερμοσίφωνα.

Because ο ενεργειακός επιθεωρητής is the subject of the sentence, while τον ηλιακό θερμοσίφωνα is the direct object.

In Greek, the definite article changes with gender, number, and case.

For masculine singular nouns:

• ο = nominative case, used for the subject
• τον = accusative case, often used for the direct object

So:

• ο ενεργειακός επιθεωρητής = the energy inspector as the person doing the action
• τον ηλιακό θερμοσίφωνα = the solar water heater as the thing being checked

This is one of the main ways Greek shows who is doing what.

They are both adjectives, but they have different endings because they must agree with the nouns they describe.

Greek adjectives agree with the noun in:

• gender
• number
• case

Here:

• ενεργειακός describes επιθεωρητής
• ηλιακό describes θερμοσίφωνα

Now look at the grammar:

• επιθεωρητής is masculine singular nominative
  → adjective: ενεργειακός
• θερμοσίφωνα is masculine singular accusative
  → adjective: ηλιακό

So the difference is mainly due to case.

A useful pattern for many masculine adjectives is:

• nominative singular: -ός
• accusative singular: -ό

Example:

• ο ηλιακός θερμοσίφωνας
• τον ηλιακό θερμοσίφωνα

There are two main clues:

1. The article and noun endings
2. The verb

In this sentence:

• ο ενεργειακός επιθεωρητής is nominative, so it is the subject
• τον ηλιακό θερμοσίφωνα is accusative, so it is the object

The verb ελέγχει means checks / inspects, so the person doing the checking is the subject, and the thing being checked is the object.

This is helpful because Greek word order can be more flexible than English. Even if the order changed, the cases would still help you identify the roles.

Ελέγχει is:

• present tense
• third person singular

So it means:

• he checks
• she checks
• it checks

In this sentence, the subject is ο ενεργειακός επιθεωρητής, so the full meaning is the energy inspector checks / is checking.

The dictionary form of the verb is ελέγχω.

A very useful mini-pattern is:

• εγώ ελέγχω = I check
• εσύ ελέγχεις = you check
• αυτός/αυτή/αυτό ελέγχει = he/she/it checks

It can mean different things depending on context, but here it most naturally means checks or inspects.

The verb ελέγχω can be used for:

• checking something
• inspecting something
• examining something
• controlling something, in some contexts

Because the subject is an energy inspector, inspects is a very natural translation in context, even if the basic meaning shown to the learner may be checks.

So this verb is broader than one exact English word.

Because Greek usually does not need a subject pronoun when the verb already shows the person and number.

In English, you must say:

• He checks

In Greek, the ending of the verb already tells you it is third person singular:

• ελέγχει

So Greek often leaves out pronouns like he, she, or it unless they are needed for emphasis or contrast.

That is why ο ενεργειακός επιθεωρητής is enough as the subject, and there is no need to add αυτός.

Yes. Greek word order is more flexible than English because case endings help show the grammatical roles.

The neutral, straightforward order here is:

• Ο ενεργειακός επιθεωρητής ελέγχει τον ηλιακό θερμοσίφωνα.

But Greek could also allow other orders, especially for emphasis, such as putting the object first. The exact effect depends on context and intonation.

However, for learners, the safest default is:

• subject + verb + object

So the sentence as given is a very natural standard order.

Yes, it is a compound noun, and Greek often forms long words this way.

Θερμοσίφωνας means water heater or boiler, depending on context. In this sentence, with ηλιακό, it means solar water heater.

You can notice the parts:

• θερμο- relates to heat
• σίφωνας is an older element found in words connected with heating/water systems

You do not need to break it apart to use it, but recognizing compounds is useful in Greek because many technical words are built this way.

Because it changes from nominative to accusative.

Masculine nouns of this type often follow this pattern in the singular:

• nominative: ο θερμοσίφωνας
• accusative: τον θερμοσίφωνα

So the final -ς disappears in the accusative singular.

This is very common with masculine nouns in Greek.

Compare:

• ο μαθητής → τον μαθητή
• ο γιατρός → τον γιατρό
• ο θερμοσίφωνας → τον θερμοσίφωνα

In this sentence, yes, it is natural to use the definite article because the sentence refers to specific, identifiable things:

• the energy inspector
• the solar water heater

Greek uses the definite article very often, sometimes more often than English.

So:

• ο ενεργειακός επιθεωρητής
• τον ηλιακό θερμοσίφωνα

sounds natural and complete.

If you wanted an energy inspector checks a solar water heater, Greek can express indefiniteness, but often it does so without an indefinite article, since Greek has no direct equivalent of English a/an.

A simple learner-friendly pronunciation guide is:

o ener-yia-KOS epitheori-TIS e-LENG-hi ton ilia-KO thermo-SI-fo-na

A few useful notes:

• γεια in ενεργειακός sounds like yia
• χ in ελέγχει is a throaty sound, not like English ch
• the stress marks show which syllable is stressed:
  • ενεργειακός
  • επιθεωρητής
  • ελέγχει
  • ηλιακό
  • θερμοσίφωνα

Listening to native audio is the best way to master this, but the stress marks are extremely helpful.

No. Ενεργειακός does not mean energetic in this sentence.

Here it means something like:

• energy-related
• energy
• concerning energy use or efficiency

So ενεργειακός επιθεωρητής is an energy inspector, not an energetic inspector.

This is a common trap for English speakers because the word looks similar to energetic, but the meaning is different.

Yes, Greek can place adjectives either before or after the noun, although the position may sound more neutral or more emphatic depending on context.

The sentence uses the very normal pattern:

• ο ενεργειακός επιθεωρητής
• τον ηλιακό θερμοσίφωνα

But Greek can also place adjectives after the noun in some cases:

• ο επιθεωρητής ο ενεργειακός
• τον θερμοσίφωνα τον ηλιακό

Those versions are much less neutral in ordinary usage and may sound marked, literary, or emphatic depending on context.

For learners, the best default is:

• put the adjective before the noun

Because τον appears before a word beginning with a vowel: ηλιακό.

In Modern Greek, the final ν in forms like τον and την is often kept before:

• vowels
• certain consonants

Since ηλιακό starts with η, which is a vowel, τον definitely keeps the ν here:

• τον ηλιακό θερμοσίφωνα

So this spelling is exactly what you should expect.