Last year looked set to be a particularly challenging one for the growth of solar power. Yet despite Donald Trump's promises to restore the fortunes of coal in solar's second-biggest market, 29.3 percent more solar cells were installed in 2017 than 2016, which had smashed previous records. Despite this, the world didn't quite manage to reach the milestone of installing 100 Gigawatts of solar capacity in the year, finishing at 98.9 GW.
The world uses 22,000 TerraWattHours of electricity each year. If that demand didn't fluctuate with season and time of day, and power sources ran 24/7 it would take 2,500 GW of electricity generating capacity to supply that. Of course, all energy sources have downtime, and night and clouds mean solar has more than most, so 98.9 GW only supplies around 0.7 percent of the world's annual electricity needs, give or take a bit for location and whether the panels are fixed or track the Sun.
The figure brings the total operating solar in the world to 405 GW, 89 percent of which was installed in the last seven years. The announcement indicates solar capacity overtook that of nuclear worldwide, although nuclear still produces more power since most plants operate for so many more hours a day.
So all this extra solar power is still a very small portion of the electricity the world uses, but the growth is extraordinary. Over the last 40 years, the amount of photovoltaic capacity commissioned in a year has doubled roughly every two years. If that rate continues, we'll be getting most of our electricity from the Sun by 2030. Even if the 29 percent growth seen in 2017 becomes the average, new solar will double every three years, and still be the largest single source of electricity by the mid-20s.
Once again, China was dominant, installing 52.8 GW, a 53 percent increase on 2016. India, at 9.6 GW is quite likely to overtake the United States this year, which fell from 14.8 to 11.8 GW. Meanwhile Europe, the one part of the world where solar installations have fallen in recent years, rebounded with 8.6 GW (up 28 percent), particularly in Turkey, which at 1.8 GW became the largest solar market in Europe for the first time.
The data comes from the Solar Power Europe report delivered at their annual summit, which every year provides an overview of solar trends for the year before. Not all countries report their solar installations reliably, or at least promptly, so estimates sometimes vary, and some have even suggested the 100 GW mark might have been reached, but Solar Power Europe's report is usually treated as the most authoritative accounting.