Even a few years ago, renewable energy played only a small role in most countries’ energy planning. While governments and publics were eager to increase the share of renewables in their energy systems, the economics of doing so were challenging. There were also serious concerns about the impact on the electricity grid of adding too much capacity from variable renewable energy sources, such as solar and wind.

This has all changed. Prices for inputs—particularly for solar photovoltaic panels and wind turbines—have come down so far that renewable power is now cost-competitive with conventional generation in some regions. As of 2014, 144 countries had established national plans to expand renewable energy, and almost hundred had set specific targets and incentives.

And as a new report from the World Bank’s Energy Sector Management Assistance Program (ESMAP) makes clear, with the right combination of new policies and investments, countries can integrate unprecedented shares of variable renewable energy into their grids without compromising adequacy, reliability or affordability.

“Renewables are no longer a marginal business,” said Anita Marangoly George, senior director of the World Bank’s Energy and Extractives Global Practice. “We are talking about levels of energy that can bring light to thousands of households, grow businesses, meet the needs of cities, and drive entire economies.”

Making the transition to large-scale renewable energy supply requires substantial shifts in thinking and infrastructure: grid modernization, adoption of new technologies, reworked business models for utilities, and updated policy and regulatory frameworks. The new ESMAP report, Bringing Variable Renewable Energy Up to Scale: Options for Grid Integration Using Natural Gas and Storage, looks at a number of new approaches to facilitate these shifts and ensure the success of this transition.