من المتوقع أن يخفض مدقق الطاقة فاتورة الكهرباء.

It is an impersonal expression meaning it is expected or it is likely.

Word-for-word, it is not something you should translate too literally. The important thing is to recognize من المتوقع أن ... as a very common pattern meaning:

• it is expected that ...
• ... is expected to ...

So the whole sentence could also be expressed in English as The energy auditor is expected to reduce the electricity bill.

Arabic often does not use a dummy subject like English it.

English says:

• It is expected that ...

Arabic simply uses the expression:

• من المتوقع أن ...

So the idea of English it is built into the expression; it does not need to be translated as a separate word.

أن introduces a following verb clause. In this sentence, it is roughly like that or sometimes an infinitive-like connector in English.

So:

• من المتوقع أن يخفض ... = It is expected that ... will reduce ... = ... is expected to reduce ...

A very important grammar point: أن causes the following imperfect verb to be in the subjunctive.

In Arabic, the imperfect verb often covers both present and future, depending on context.

Here, the future meaning comes from من المتوقع. Because the sentence is about an expected result, يخفض is understood as future:

• أن يخفض = that he/it will reduce = to reduce in English-style restructuring

So Arabic does not need سـ or سوف here.

Because after أن, standard Arabic normally uses the imperfect subjunctive directly:

• أن يخفض

Using أن plus سيخفض is generally not the standard pattern here.

So the natural MSA structure is:

• من المتوقع أن يخفض ...

not

• من المتوقع أن سيخفض ...

Here it is most naturally understood as يُخَفِّضَ meaning to reduce / lower.

A useful thing to know: ordinary Arabic writing often leaves out short vowels and the shadda, so يخفض can represent a more fully vocalized form.

In this sentence, the fully vocalized form is:

• يُخَفِّضَ

That is from the verb خفّض = to reduce / lower.

Because it comes after أن, the final vowel is -a in careful MSA pronunciation.

Because Arabic very often uses verb–subject–object order, especially in formal written language.

So:

• يخفض مدقق الطاقة فاتورة الكهرباء

is a normal Arabic order:

• يخفض = verb
• مدقق الطاقة = subject
• فاتورة الكهرباء = object

Arabic could also use a subject-first order in some contexts, but the verb-first order here is completely natural.

مدقق الطاقة is an iḍāfa construction, often called a construct phrase.

It consists of:

• مدقق = auditor / checker / inspector
• الطاقة = energy

Together, it means energy auditor.

In an iḍāfa:

• the first noun normally does not take الـ
• the second noun determines whether the whole phrase is definite

So مدقق الطاقة is the normal Arabic way to say the energy auditor or energy auditor, depending on context.

Yes. It is another iḍāfa phrase.

• فاتورة = bill / invoice
• الكهرباء = electricity

So:

• فاتورة الكهرباء = electricity bill = literally bill of electricity

Again, the first noun does not take الـ, and the second noun makes the whole phrase definite.

A careful fully vocalized version is:

مِنَ الْمُتَوَقَّعِ أَنْ يُخَفِّضَ مُدَقِّقُ الطَّاقَةِ فَاتُورَةَ الْكَهْرَبَاءِ

The important endings are:

• المتوقعِ → genitive, because it comes after من
• يُخَفِّضَ → subjunctive, because it comes after أن
• مدققُ → nominative, because it is the subject
• الطاقةِ → genitive, because it is the second part of an iḍāfa
• فاتورةَ → accusative, because it is the direct object
• الكهرباءِ → genitive, because it is the second part of an iḍāfa

In normal unvocalized writing, these endings are usually not shown.

Not always.

Grammatically, both مدقق الطاقة and فاتورة الكهرباء are definite-looking phrases because of the iḍāfa structure with a definite second noun. But English may translate them more flexibly depending on context.

So مدقق الطاقة could be rendered as:

• the energy auditor
• sometimes an energy auditor, if the context is generic

But in a sentence like this, the energy auditor is a very natural translation.