When your tenant was not paying rent regularly and stopped paying the same to you, should have issued a legal notice to evacuate the rented premises and also demand the pending rent. Later if he didn't comply with the notice you could have sued him in competent court.
But in your case, as the tenant has left the said premises without paying rent, you can recover the arrears of rent together with the unpaid electricity bills.
You have to contact your local lawyer for the purpose of recovering the rent as well as the unpaid electricity bills.
Also, it is relevant to see in your case on what grounds your tenant was occupying the said premises without a valid tenancy agreement.
If you are unable to recover the rent anyhow from the tenant, you have to pay the electricity bill and other costs in order to avoid penalty and interest at bank rate.
Hope this answer helps you.