Mahsuplaşma ihtiyaç fazlası enerjiyi de içeriyor.

Because it is the direct object of the verb içeriyor (includes / is including), and it is treated as specific/definite.

• enerji = energy
• enerjiyi = the energy / energy (as a specific thing being referred to)

The ending -yi is the accusative case suffix.
In Turkish, a definite direct object usually takes this ending.

So:

• enerji içeriyor can sound more general
• enerjiyi içeriyor points to a specific energy category: in this case, ihtiyaç fazlası enerji

Because enerji ends in a vowel, the accusative appears as -yi with a buffer y:

• enerji + i → enerjiyi

Here, de means also / too / as well.

So enerjiyi de means:

• the energy too
• surplus energy as well

It shows that this is an additional thing included in the netting/reconciliation process.

A very important point: this de is a separate word, not the locative suffix -de / -da meaning in / at / on.

Compare:

• evde = in the house → suffix
• ev de = the house too → separate word

In your sentence, it is definitely the separate word meaning also.

Because de usually comes after the word or phrase it adds the meaning of “also/too” to.

Here, the thing being emphasized as an addition is ihtiyaç fazlası enerjiyi.

So:

• ihtiyaç fazlası enerjiyi de içeriyor = it includes surplus energy too

This placement is very natural in Turkish.
It tells you that surplus energy is one more item among the things included.

If you moved de elsewhere, the emphasis could change.

İhtiyaç fazlası enerji means something like surplus energy, excess energy, or energy beyond what is needed.

It is built from:

• ihtiyaç = need
• fazla = too much / extra / excessive
• fazlası = the excess / the surplus of something

So ihtiyaç fazlası literally suggests:

• the excess beyond need
• more than needed

Used before enerji, it describes the type of energy:

• ihtiyaç fazlası enerji = energy that exceeds need

This kind of structure is very common in Turkish.

Because ihtiyaç fazlası is a fixed noun phrase meaning surplus relative to need or excess over need.

There is a difference between:

• fazla enerji = extra energy / too much energy
• ihtiyaç fazlası enerji = energy beyond what is needed, surplus energy

So fazlası is not random here. It is part of a common Turkish construction where one noun helps define another in a more specific way.

You can think of ihtiyaç fazlası as a set phrase meaning:

• surplus to requirements
• in excess of need

İçeriyor is the -iyor form of the verb içermek (to include / contain).

So:

• içermek = to include
• içeriyor = is including / includes

Even though -iyor is often taught as the present continuous (is doing), in modern Turkish it is also very commonly used for general present statements, especially in everyday language.

So in a sentence like this, içeriyor does not necessarily mean something temporary happening right now. It can simply mean:

• includes
• does include

İçerir is also possible in some contexts, but it sounds more:

• formal
• general
• matter-of-fact
• sometimes more written or technical

In many real-life contexts, Turkish speakers prefer içeriyor.

The subject is Mahsuplaşma.

The sentence structure is:

• Mahsuplaşma = subject
• ihtiyaç fazlası enerjiyi de = object phrase
• içeriyor = verb

So literally, the structure is:

• Netting/reconciliation
  • surplus energy too
    • includes

Turkish normally places the verb at the end, so this word order is very natural.

Here, Mahsuplaşma is a noun.

It comes from a verb-related base and refers to a process or procedure. In many contexts, it means something like:

• offsetting
• netting
• reconciliation
• settlement by balancing amounts

For a learner, the key point is that in this sentence it behaves as a singular noun subject.

That is why the verb is singular:

• Mahsuplaşma ... içeriyor = Netting/reconciliation includes ...

Turkish does not have a direct equivalent of the English article the.

Whether something is understood as:

• energy
• the energy
• surplus energy
• the surplus energy

depends on context, word order, and case marking.

In this sentence, the accusative -yi on enerjiyi helps show that this is a specific, identifiable object, which often corresponds to English the.

So Turkish does not need a separate word for the.

Turkish word order is somewhat flexible, but this version is very natural.

The neutral pattern is often:

• Subject + Object + Verb

So:

• Mahsuplaşma ihtiyaç fazlası enerjiyi de içeriyor.

That said, Turkish can move things around for emphasis. For example, a different order might highlight a different part of the sentence. But the verb usually stays near the end in standard statements.

This sentence sounds normal and unmarked:

• subject first
• object before the verb
• verb last

Because the accusative ending goes on the head noun of the object phrase, which is enerji.

The whole object is:

• ihtiyaç fazlası enerji

When that whole phrase becomes the definite direct object, the case marker appears on the final noun:

• ihtiyaç fazlası enerjiyi

This is very common in Turkish. In multi-word noun phrases, the case ending usually appears on the last word of the phrase.

So:

• ihtiyaç fazlası enerji = surplus energy
• ihtiyaç fazlası enerjiyi = the surplus energy / surplus energy (as a specific object)

A rough English-friendly guide would be:

• Mah-su-plash-ma
• eeh-tee-yach fahz-lah-suh
• eh-nehr-zhee-yee
• deh
• ee-cheh-ree-yor

A few helpful pronunciation points:

• ş sounds like sh
• ç sounds like ch
• c in Turkish sounds like English j
• ı is a vowel that does not exist in English; it is a relaxed sound somewhat like the vowel in roses for many speakers, but further back
• içeriyor has four clear syllables: i-çe-ri-yor

You do not need to pronounce it exactly like an English spelling. The most important thing is to keep the Turkish vowels fairly clear and consistent.