Staff at Ocker Hill Academy, off Gospel Oak Road, have also been unable to send out messages to parent to inform them, due to a school system being affected by the outage.
The school currently has 250 pupils on roll.
A statement from the school read: "Due to the power outage at school - and therefore being unable to access school systems and parents app - we are unable to send out messages about the closure.
"Could we please ask you all to do your best to spread the message far and wide? Thank you."
The school plans to be back open on Thursday, but aims to update parents as soon as possible.