Dec 14 (Reuters) - Royal Dutch Shell (RDSa.L) said on Tuesday it would buy U.S.-based solar and energy storage developer Savion from Macquarie"s (MQG.AX) Green Investment Group, to expand its global solar portfolio as part of its push to move to net zero emissions. The oil major did not disclose the value of the deal, but said the acquisition adds on to its previous investment in U.S. solar power operator Silicon Ranch, with Savion"s more than 18 gigawatts of solar power and battery storage under development for many customers. Last year, London-listed Shell laid out the oil and gas sector"s most extensive strategy yet to reduce greenhouse gas emissions to net zero by 2050, stating its plans depended on its customers also mitigating emissions. "Savion"s significant asset pipeline, highly experienced team, and proven success as a renewable energy project developer make it a compelling fit for Shell"s growing integrated power business," said Wael Sawan, the director of Shell"s integrated gas and renewables and energy solutions. Renewable energy should account for nearly 95% of the increase in power capacity in the world through 2026, a report by the International Energy Agency (IEA) showed earlier this month, with solar power providing for more than half the boost.