Major U.K. retailer Marks and Spencer (M&S) has entered into a strategic partnership with Octopus Energy to supply energy and services under the M&S Energy brand.

The partnership will begin in September and will see M&S Energy offer its customers 100 percent green energy, the store said in a statement Wednesday. The U.K.’s largest investor in solar farms, Octopus has also made investments in wind generation and anaerobic digestion plants.

The team-up will replace M&S’ contract previously held by energy business SSE. Under that arrangement, SSE also offered customers 100 percent green energy, according to CNBC.

“As we continue to transform M&S we have chosen Octopus as a new strategic partner for M&S Energy,” Jonathan Hazeldine, the head of M&S Energy, said. “Octopus’ values of responsible and transparent pricing and digital-first customer service mirror our ambitions for the business.”

Hazeldine added that together, the two businesses could challenge the traditional energy market and “bring green energy to millions of households at a competitive and fair price.”