Is a landlord or owner of a property liable for outstanding energy bills, if said owner of property never signed contract for utilities to be turned on for unofficial tenant.

If the tenant was responsible for the utilities they would be turned on by the tenant. Not sure what an unofficial tenant is.

Someone who moved onto my property without signing a lease or contract, basically a freeloader.

Who ever signed for the electric at the electric company is responsible.

If the tenant signed up and the utilties are in their name, they are responsible, if the utilities are in your name, you are responsible

So it all depends on who put their name on the line that promised to pay.

Why are you even dealing with this person. They are a trespasser. Have them arrested for trespassing.

Thank you it helped it was my aunt who was seriously injured in a auto accident the house was empty so we let her live there for nothing until she got better, she signed to have utilities turned on but not she has them shut off (no income to pay them) and the utility company is telling us since we own the house we are responsible for the bill, but they were in her name she had them turned on in her name and signed for them. There is not lease or no agreement we let her live there out of the goodness of our hearts to help her out

She was a renter for all legal purpose, here is no requirement that a rental agreement be in writing. You need to inform them of this, and that as the owner of the property you are not responsible for what bills your tennants make.

Is a landlord or owner of a property liable for outstanding energy bills, if said owner of property never signed contract for utilities to be turned on for unofficial tenant.
By legislaltion - this often happens. Landlords need to know if local utility companies CAN go after the landlord and if they CAN, then the landlord needs to make sure the tenant has paid all bills prior to refunding their security deposit.

In the case of municiple utilities, these unpaid bills create a lien v the property.