Then you will be without energy as all suppliers perform credit checks, its the depth of the check that makes the difference (Hard check or soft check), most are soft checks and they have very little impact on your credit file, the same as searching for car insurance or a new current account without an overdraft. Hard checks stay on your file for 3-5 years after they have been closed.
British Gas were the only supplier to add an account to my credit files that remains for 6 years after I've switched away. No other supplier I've used has done that.