Could a person, who uses electricity but has no electricity supply contract concluded with the distribution company, be deemed as consumer?

There are still electricity users who have not concluded electricity supply contracts with the supplier, but pay the consumption based on invoices issued by the supplier. However, they are deemed to have contractual relations, because one of them supplies electricity, and the other pays the consumption based on invoices issued by the first. All electricity users who have contractual relations with the supplier but, due to various reasons, have not concluded in writing electricity supply contracts with the supplier are deemed to be electricity consumers.