Þú getur notað rafmagnið hér.

Icelandic modal verbs (like getur, má, vil, þurfa) require the past participle of the main verb, not the bare infinitive. So nota (to use) becomes notað (used) after getur.
Example:
• Þú getur tekið bókina. (not taka)
• Hún má ekki truflað mig. (not trufla)

Icelandic marks the definite article as a suffix.
• rafmagn = “electricity” (indefinite)
• rafmagnið = “the electricity” (definite)
Here you’re talking about the power supply available here, so you add -ið for neuter singular definiteness.

Yes.
• Þú mátt nota rafmagnið hér. – Emphasizes permission (“you may/are allowed to”).
• Þú getur notað rafmagnið hér. – Emphasizes ability/possibility (“you can/are able to”).
In everyday speech they often overlap when you’re simply granting someone the go-ahead.

Icelandic uses V2 word order: the finite verb (getur) stays in second position. Here the subject Þú is first, so everything else (object + adverb) follows.
You can front hér (making it first), but then getur must remain second:
• Hér getur þú notað rafmagnið.
Otherwise, placing hér before Þú in third position would break V2.

It’s the direct object of nota, so it’s in the accusative case.
Neuter nouns have identical nominative and accusative singular forms, which is why rafmagnið looks the same in both.

Approximate IPA:
/θuː ˈcʰɛːtʏr ˈnoːtaːð ˈravmaɲknɪː θjɛːr/
Tips:
• Þ/θ = English “th” in thing
• ú/ uː = long “oo” as in food
• g in getur is palatalized ([cʰ])—start like a “k” but middle-tongue raised
• Final ð in notað = voiced “th” in this
• gn in rafmagnið = [ɲ], like Spanish ñ in año

No. Modal verbs in Icelandic (getur, má, vil, þarf) are followed directly by the past participle—no að.
✗ Þú getur að notað rafmagnið
✓ Þú getur notað rafmagnið