Production tax credit (PTC) rules mean projects must start construction this year to receive the $0.023/kWh credit.
The timing of the new build is uncertain, said the EIA, and will depend on how quickly wind purchase and financing activities gear up.
Market analysts told the recent American Wind Energy Association conference that most additions will come in 2014, with estimates ranging from 5.5-8.5GW compared to 2-3GW this year.
Make Consulting's Dan Shreve had thought 2013 build could go higher, but said delays in getting the new PTC rules and ongoing questions about how they will be applied make that unlikely.
"We're seeing a lot of delay in terms of order flow in the US marketplace. There is a great deal of discussion, there's a tremendous amount of RFP activity, but at the end of the day it is going quite slowly."