California has ambitious plans for its energy mix, having set itself the target of generating 50 percent of its electricity from renewable sources by 2030.

Major utility Southern California Edison (SCE) delivers electricity to over 14 million people in a 50,000 square mile area across central, coastal and southern California.

Pedro Pizarro is the president and CEO of SCE's parent company, Edison International.

"Sustainability is really at the core of what we do and the electric grid will be at the very core of helping the state meet those very ambitious goals," he told CNBC's Sustainable Energy.

With the energy mix changing and renewables becoming increasingly important to the business, there are several factors and challenges which need to be taken into account.

Wind, Pizarro said, occupied an important place in his company's resource mix and accounted for around 10 percent of the total energy it delivered to customers.

"It's here to stay," he explained. "It is a variable resource, it's intermittent, and that can challenge its value at times." This issue of what to do when the wind doesn't blow or the sun doesn't shine is a challenging one. It's within this context that storage is becoming increasingly important.

At a battery storage facility in Ontario, California, SCE is collaborating with Tesla. According to SCE, when demand is low lithium ion batteries can be charged, storing enough energy to power 15,000 homes for four hours.

"The Mira Loma battery storage project demonstrates that energy storage is part of (the) energy mix now," SCE's Vibhu Kaushik said.

"These projects can be built very quickly, scaled as needed, (and) they're really good at integrating renewable energy," he added.