The bond was four times oversubscribed despite yielding only 2.5 per cent interest annually, the lowest rate offered by Iberdrola to date, in a sign of strong investor demand for green products.
The Spanish utility, which owns Scottish Power, will benefit from a reduced cost of finance and a longer debt profile, with repayment scheduled for October 2022.
Environmental audit specialist Vigeo certified that the bond, which refinances existing debt, would go to green projects.
French utility EDF was the first large corporation to issue a green bond last November, raising €1.4 billion (£1.2 billion). Consumer goods giant Unilever followed suit last month with a £250 million issue.
Prior to EDF’s move, the majority of green debt was issued by organisations such as the World Bank and the European Investment Bank.
According to investment banking consultancy Dealogic, the green bond market grew more than fivefold last year, with 29 deals worth a total of $11.2 billion (£6.69 billion).