In recent years, developing countries have made huge investments to expand power supply networks, but India's outages - which left 670 million people without power this week - demonstrate that reliability remains a major problem.
The collapse of three interconnected power grids caused havoc on the streets as traffic lights stopped working. Trains ran late, if at all. And people in shops and businesses across the north of India tried to work by candlelight.
It is being called the worst electrical blackout ever, with 10 percent of the world's population affected. And it hit at the worst time, said a businessman in the northern Indian city of Srinagar, Niyaz Ahmed.
"This is summer time and hospitals, air conditioning and factories are not able to function," he said. "People are facing many problems due to this failure."
Developing countries have invested heavily in recent years to expand power supply networks. But while India has four times the population of the United States, its power grid can handle about a fifth of the capacity, says Columbia University engineering professor Vijay Modi.
"You rely on a system where you pay people, large users, not to use electricity. You simply do not have enough," he said.
More than a fifth of the world's population has no access to electricity. Even where grids have been built, World Bank energy expert Vijay Iyer says an economy cannot function normally without a guaranteed supply.
"So you might have access but if you do not get 24/7 reliability that access is not helpful for you because you cannot predict, and you cannot plan on how you conduct your economic activities on a day-to-day basis if you do not know whether you will have the power or not," he said.
Iyer says developing countries need to diversify energy sources and install smart grids.
"Grids that in the old sense that used to derive power from one source, but now they are deriving power from multiple sources," he said. "So grids have to be able to adapt at very short intervals. Wind starts to blow, so wind power is coming into the system, it has to adjust immediately to take that power on board and shut down something else."
Even for developed economies, maintaining grids can be a problem. The United States has been installing smart grids and shoring up networks against cyberattacks. But storms earlier this summer knocked out power to around two million people in and around the nation's capital.