IBEI strongly recommends that you open a bank account in Spain, especially if you are considering extending your residence permit when staying for more than a year. There are many options and banks do not usually require much documentation.
You can walk into any bank and ask to open a bank account. Make sure you have some of the basic documentation you might need.
When opening a local bank account, make sure you have your ID/passport with you (if you have your TIE it will be preferred), as well as your IBEI acceptance letter and your empadronamiento certificate.