Brookfield Renewable Partners launched a bid to take full control of US-based wind and solar owner TerraForm Power, in a move the former said would cement its place as one of the world’s largest pure-play renewable energy operators.

Brookfield Renewable and its affiliates already hold 62% of TerraForm Power, which operates more than 4GW of wind and solar, mostly in the EU and Europe.

Brookfield Renewable, part of Canadian investment giant Brookfield Asset Management, is offering a share-based deal that it said values Terraform Power’s stock at $17.31, an 11% premium on its closing share price on Friday.

Launching the unsolicited offer, Brookfield – which took control of Terraform Power in 2017 – said the acquisition would “strengthen Brookfield Renewable’s position as one of the largest publicly-traded, globally-diversified, multi-technology, pure-play renewable power platforms with $50bn in total power assets”.

It added: “TerraForm Power shareholders, in turn, will benefit from access to a broader growth mandate that includes global, multi-technology and development opportunities, and increased access to capital and liquidity, underpinned by an investment grade balance sheet.”

Brookfield has emerged as one of the world’s most active renewable energy investors, citing a 19GW operating portfolio and 13GW pipeline.

TerraForm Power issued a statement confirming the unsolicited bid, and announcing formation of a special committee to consider it and report to shareholders. Its shares were up 9% to $17.01 in pre-market trading in New York.

TerraForm Power and its smaller sister group, TerraForm Global, were the two ‘yieldcos’ originally set up as repositories for projects developed by the now bankrupt US group SunEdison.