Iberdrola was the largest corporate issuer of the year, raising €2.45 billion ($2.7 billion) in three transactions.
It beat Netherlands-based national electricity operator TenneT, which raised $2.2 billion, also through three green bonds.
The Spanish utility has already sent out a signal that it means to continue in a similar manner in 2017, upsizing an issue in March this year from 750 million to 1 billion, and securing a 600 million green loan from Spanish bank BBVA.
This latest green bond issue makes it the third largest ever corporate issuer overall, behind EDF and Engie, according to data from Environmental Finance's Green Bond Database.
Iberdrola's head of treasury and financing, Jesús Martínez Pérez, is optimistic the company will continue 2017 as it started, with more issues and other forms of green financing, such as the BBVA loan.
Proceeds from the company's bonds are used to refinance existing wind power projects, both onshore and offshore, in Western Europe.
Iberdrola's first issue of 2016, in April, was its largest, raising €1 billion. This was followed in September by a 700 million bond.
Finally the firm came to the market again in November, raising €750 million. 2016 was not entirely successful for Iberdrola in the green bond market, however, as it was removed from the Barclays MSCI green bond index after a review of its rules.
The ratings agency enhanced its methodology and tightened the requirements for bonds to be included on the index. This included introducing a six-month deadline for issuers to provide full documentation on the use of proceeds following a bond's issue, which resulted in bonds from Iberdrola being permanently excluded.
Previously, bonds had remained under review indefinitely. Martínez Pérez is not concerned by the company's removal from index, dismissing it as 'a technical matter regarding the procedures this index uses'.