The Three Stumbling Blocks to a Solar-Powered Nation

Every hour, the sun bombards the Earth with enough light to satisfy our energy needs for a year, but there are barriers to our solar-energy future

By Christopher Mims of The WSJ. Excerpts:

"For solar power to meet 30% of the world’s electricity needs, it will need to fall from its current cost of a dollar per watt of electricity to 25 cents per watt, says Varun Sivaram, a science and technology expert at the Council on Foreign Relations, a nonprofit think tank.

The only way to get there, Dr. Sivaram argues in his forthcoming book, is by bringing to market solar-cell technologies that are currently still far from mass production, such as perovskite-based solar cells.

Perovskite cells can be made from materials that could be radically cheaper than conventional silicon. They can also take on novel forms, such as a tint on windows or thin printable sheets. But they still face significant barriers to commercialization: They tend to rapidly degrade when wet, and scientists can’t create large cells with the same efficiency as the small ones they can make in a lab.

While perovskite is promising, there’s no guarantee we’ll get it or any other better, cheaper technologies when we need them, because the energy industry isn’t investing enough in research and development to bring them to market, says Dr. Sivaram.

Energy companies tend to spend 1% to 2% of their revenue on R&D, he says, whereas semiconductor companies can easily spend 10 times as much. The U.S. federal budget for energy research, $5 billion a year, is likely to be eclipsed by China’s budget for such research by 2020, he adds.

One reason we’re going to need cheaper solar cells is that the more solar there is on the grid, the less valuable it is to add more. This happens because sunlight is intermittent. It isn’t hard to get to the point where solar is producing too much power at some times of day, and none at all when it’s needed most. The first solar panel added to the grid helps offset midday consumption, but the last one to be added might be completely unnecessary, because the grid might already be saturated when it’s capable of producing the most power.

California, which gets about 10% of its electricity from solar power, already has this problem. On some sunny days, it has to pay other states to take electricity off its hands.

One solution is utility-scale power storage. But putting enough batteries on the grid to make a meaningful dent is a truly gargantuan feat, and batteries are still far too costly to address it at scale."