A cameraman takes video of a Nissan Sylphy Zero Emission, the Nissan's first all-electric vehicle built in China, at the Nissan factory in Guangzhou, Guangdong province, China, Monday, Aug. 27, 2018. The Sylphy is part of a wave of dozens of electric models planned by global automakers for China where the government is pressing them to accelerate development of the technology. (AP Photo/Vincent Yu)

BONN - Electric vehicles will be the main form of mobility in the coming years, and the challenge of making smart charging technology using weather conditions is becoming increasingly pressing, International Renewable Energy Agency (IRENA) officials told reporters on the sidelines of its Innovation Week in Bonn.

"Electric mobility will become the main form of mobility in some 7-8 years," Adnan Amin, IRENA director-general, said.

About 4 million electric vehicles are out in the world at the moment, Dolf Gielen, director of IRENA innovation and technology center, said at a briefing .

"That is about half a percent of the global vehicles stock, so it's still a relatively small percentage, but it's growing very rapidly," Gielen said.

According to Amin, the number of electric vehicles grew by 77 percent last year.

"In a country like Norway, the majority of car sales is electric at this moment. That's going to have a very significant effect on the transport sector of course, on the gasoline demand, but also it opens up new opportunities to integrate more renewables," Gielen said.

Smart charging, which employs renewable energy, such as sunlight or wind, could be one of these opportunities.

"At the moment, there is not that much smart charging. So that is really something that requires much more attention. It means that you need charging equipment in place that either responses to a price signal or that can be remotely controlled. It also means that you need to have these cars connected to grid at the moment there is that electricity available," Gielen said.

A connection in the office would be needed for a midday photovoltaic system, while charging by wind in the evening would require a connection when parked in the city, Gielen explained.

"That's going to be a significant challenge as we ramp up electric vehicles now in the coming years ... It can be done, but it needs to be managed," IRENA official added.

The Innovation Week in Bonn, held Wednesday through Friday this year, brings together officials, entrepreneurs and innovators and focuses on renewable power transition.