Hi ,
Myself and my wife own a house in VA for the past 5 years. We both are on the title. Current loan is on my name only and my wife is not there on the loan.

I am planning to refinance and keep it only on my name. My wife will be out of country for some time. Is there any signature I need to get from her when I refinance? If I get a power of attorney something like that will it be OK?

Yes, she will need to sign the new mortgage. You should be able to use a POA but you have to make sure that it's properly filled out for refinancing purposes or the lender and title company won't accept it.