MADRID/COPENHAGEN (Reuters) - Europe's largest utility Iberdrola and Norway's $1.6 trillion sovereign wealth fund are building up on their existing partnership in renewables to jointly invest more than 2 billion euros ($2.15 billion) in Spain and Portugal.

The deal is in line with Iberdrola's strategy of selling minority stakes in renewable projects to help fund its large investments in new projects and network assets.

The Spanish firm and Norges Bank Investment Management (NBIM), the operator of the Norwegian fund, said on Thursday they reached an agreement for the fund to buy a 49% stake in a 644 megawatt portfolio of Spanish solar projects from Iberdrola for 203 million euros.

The latest addition, projects with long-term contracts to sell part of the energy they will produce, takes the overall partnership to roughly 2.5 gigawatts, including some wind farms, representing an overall investment of more than 2 billion euros.

Iberdrola, which will keep a 51% stake in the assets, said the parties could team up in the future in other countries too.

Last month, the Spanish firm presented a 41 billion euro investment plan to push ahead with its strategy strategic shift towards upgrading and expanding grids in the United States and elsewhere while taking a more selective approach to renewable energy.

It said around 5 billion euros would come from partners in renewables.

($1 = 0.9323 euros)

(Reporting by Stine Jacobsen and Pietro Lombardi, editing by Terje Solsvik, Inti Landauro and Miral Fahmy)