Del. Code tit. 26, § 217

In default of compliance with any order of the Commission when the same becomes effective, the public utility affected thereby shall be subject to a penalty of up to $1,000 per day for every day during which such default continues, to be recovered in an action in the name of the State. Observance of the orders of the Commission may be compelled by mandamus or injunction in appropriate cases, or by an action to compel the specific performance of the orders so made or of the duties imposed by law upon such public utility.