Proje sadece öz tüketimi değil, aynı zamanda mahsuplaşmayı da içeriyor.

The basic structure is:

Proje + ... içeriyor

So:

• Proje = the project → the subject
• içeriyor = includes / is including / contains → the verb

Everything in the middle is what the project includes:

• sadece öz tüketimi değil = not only self-consumption
• aynı zamanda mahsuplaşmayı da = but also netting/offsetting/account reconciliation

So the overall pattern is:

X sadece A değil, aynı zamanda B de/da içeriyor
= X includes not only A, but also B

This is a very common Turkish pattern meaning:

not only ..., but also ...

In this sentence:

• sadece öz tüketimi değil = not only self-consumption
• aynı zamanda mahsuplaşmayı da = but also netting/offsetting

A very literal breakdown would be:

• sadece = only
• değil = not / is not
• aynı zamanda = at the same time / also
• da = also, too

Together, they create the fixed contrastive structure:

sadece A değil, aynı zamanda B de/da
= not only A, but also B

Because öz tüketimi is functioning as a definite direct object here.

The noun phrase is based on öz tüketim, which means self-consumption. In the sentence, it appears as:

• öz tüketimi

That final -i is the accusative marker, used because it is the object of içeriyor.

Compare:

• Proje öz tüketim içeriyor → less natural here; sounds more indefinite or incomplete
• Proje öz tüketimi içeriyor → The project includes self-consumption

So öz tüketimi is the object form needed in this sentence.

For the same reason: it is also a direct object of içeriyor.

• mahsuplaşma = netting / offsetting / reconciliation
• mahsuplaşmayı = that noun in the accusative form

The ending is:

• -yı / -yi / -yu / -yü after a vowel-final noun
• Here, mahsuplaşma ends in a vowel, so Turkish inserts y before the accusative ending:
  • mahsuplaşma + yı = mahsuplaşmayı

So both items being included by the project appear as accusative objects:

• öz tüketimi
• mahsuplaşmayı

Because they do different jobs.

• -yı = accusative case ending
• da = also / too

So:

• mahsuplaşmayı = the netting/offsetting as the object
• mahsuplaşmayı da = the netting/offsetting too / also

In the pattern not only A, but also B, Turkish often puts de/da on the second item:

• sadece A değil, aynı zamanda B de/da

So here:

• öz tüketimi değil
• mahsuplaşmayı da

This makes the second item explicitly mean also B.

Öz tüketim literally means something like self-consumption.

In many technical, economic, or energy contexts, it refers to consuming what you yourself produce. For example, in a solar-energy context, it can mean using the electricity generated on-site instead of selling it to the grid.

So:

• öz = self / own
• tüketim = consumption

Together:

• öz tüketim = self-consumption
• öz tüketimi = self-consumption, as the object in this sentence

Mahsuplaşma is a technical or administrative term. Its exact English equivalent depends on context, but common translations include:

• netting
• offsetting
• reconciliation
• sometimes settlement

In energy or billing contexts, it often refers to balancing one amount against another, such as electricity produced versus electricity consumed.

It comes from the verb mahsuplaşmak, which is related to settling or offsetting accounts.

So in this sentence, the idea is that the project includes not only self-consumption, but also some kind of accounting/offsetting mechanism.

Literally, aynı zamanda means at the same time.

But in actual usage, it often works like:

• also
• as well as
• furthermore
• at the same time

In this sentence, it is part of the fixed expression:

sadece ... değil, aynı zamanda ... da

So even though aynı zamanda literally means at the same time, here you should understand it as part of not only ..., but also ...

Both are possible in Turkish, but they give slightly different tones.

• içeriyor = present continuous form, often used in modern Turkish for current statements and even general descriptions
• içerir = aorist/simple present, often more formal, timeless, or definition-like

So:

• Proje ... içeriyor = The project includes ...
• Proje ... içerir = The project includes ... too, but it can sound more formal or written

In everyday modern Turkish, -iyor forms are very common even when English would use the simple present.

Because it is the subject of the sentence, and subjects in Turkish are normally in the basic dictionary form, called the nominative.

So:

• Proje = subject
• öz tüketimi and mahsuplaşmayı = objects

Turkish often marks objects more clearly than subjects. That is why the objects have endings, but Proje does not.

Yes, Turkish word order is flexible, although some versions sound more neutral than others.

The given sentence is natural and clear:

Proje sadece öz tüketimi değil, aynı zamanda mahsuplaşmayı da içeriyor.

You could also move things around for emphasis, for example:

• Proje, sadece öz tüketimi değil, aynı zamanda mahsuplaşmayı da içeriyor.
• Sadece öz tüketimi değil, aynı zamanda mahsuplaşmayı da proje içeriyor.
  This is grammatical, but less neutral and more emphatic.

The most neutral order in ordinary prose is usually the one you were given.

The comma before aynı zamanda is very common and helpful, because it separates the two parts of the not only ..., but also ... structure.

So this is natural:

• Proje sadece öz tüketimi değil, aynı zamanda mahsuplaşmayı da içeriyor.

You may sometimes see Turkish commas used a bit more or a bit less depending on style, but here the comma is normal and useful.

The choice between de and da follows vowel harmony.

• after front vowels → de
• after back vowels → da

Since mahsuplaşmayı contains back vowels, da is correct:

• mahsuplaşmayı da

So this is not a meaning difference. It is the same word, just changing form to match vowel harmony.

Değil often means is not / not, but in this sentence it is part of a larger contrastive structure:

sadece A değil, aynı zamanda B de
= not only A, but also B

So here değil is not just denying something by itself. It is setting up a contrast:

• not just A
• but also B

That is why translating it word-for-word as only not can feel incomplete unless you read the whole structure.

It sounds fairly neutral-to-formal, and somewhat technical because of the vocabulary:

• öz tüketim
• mahsuplaşma

Those are not the most basic everyday words, especially mahsuplaşma, which sounds administrative, financial, or technical.

So the grammar is completely normal, but the sentence belongs more to professional, business, legal, energy, or policy language than casual conversation.