WHEN SATELLITES TRAIN their cameras onto Africa at night, it is almost as if they are peering back to an age before electricity. The rich world is awash with great glowing orbs for the main population centres and orange tentacles for the roads that link them. But apart from speckles of light around the biggest cities, much of Africa is dark.

Of all the measures of the continent’s poverty, few are starker than that about two-thirds of its people have no access to reliable electricity. The Africa Progress Panel (APP), a group of experts led by Kofi Annan, a former UN secretary-general, puts the number of Africans without any power at 620m, most of them in villages and on farms. The panel found that in nine African countries fewer than one in five primary schools had lights. A study by the World Health Organisation found that about a quarter of clinics and hospitals in 11 African countries have no power of any kind, and many of the rest get it from generators that often break down or run out of fuel.

Such power shortages cost lives. In Nigeria each year an estimated 36,000 women die during pregnancy or childbirth, many because they deliver their babies in the dark in clinics such as the one in Makoko, a slum perched on stilts above a lagoon in Lagos, Nigeria’s biggest commercial city. It has just a few rough wooden beds in a small room with a doorway so low that people have to stoop to enter it. Straightforward deliveries are done by candle and torchlight, says one local resident, a fisherman. If anything goes wrong, the mother is carefully passed down to a small fishing canoe and taken to a bigger hospital across the lagoon. By then it is sometimes too late. Without power even the simplest health precautions can become difficult. “If you don’t have electricity you don’t have a fridge, and if you don’t have a fridge you can’t store vaccines,” says Jasper Westerink, who runs the African business of Philips, a Dutch multinational firm.

Businesses across the continent have to contend with frequent blackouts, known as dumsor in Ghana, from the Asante words for “off and on”. They rely on expensive backup generators, so the electricity they use is among the costliest in the world. The full impact of intermittent and high-cost energy on Africa’s economy and society is hard to measure, but it seems safe to say that this is the biggest single barrier to development.

The World Bank reckons that if they had continuous energy supplies, sub-Saharan Africa’s economies could be growing by two percentage points a year faster, on average, than they do now. A more limited study looking at the impact of blackouts on small firms in Ghana found that power shortages sometimes almost halved their revenues, and in aggregate cost the economy about 2% of GDP. Putting this right will require a huge investment in generating capacity. But thanks to a happy combination of innovation and falling costs for renewable energy, Africa may now be able to leapfrog ahead not once but twice, skipping both polluting fossil fuels and, often, the electricity grid itself. Last year Africa added a record 4,400MW of renewable-power capacity, roughly enough to meet Nigeria’s current consumption, according to the International Energy Agency (IEA). This is partly due to falling costs: the price of solar panels has come down by more than 80% since 2010, and that of wind turbines is also dropping fast. A recent study led by Anton Eberhard of the University of Cape Town found that grid-connected wind and solar renewable energy in South Africa is now among the world’s cheapest. But the dash for renewables also has to do with geography. One of the fastest-growing sources of renewable energy in Africa is hydropower as Africa dams its biggest rivers, including the Blue Nile, across which Ethiopia is building the Grand Renaissance Dam. When it is finished in a few years’ time it will more than quadruple the country’s electricity-generating capacity, from about 2,200MW to 8,700MW. The Congo river, for its part, has the potential for the world’s largest hydropower station, with a theoretical output of about 40,000MW, where it plunges down a set of rapids between Kinshasa, the capital, and the sea. If it were ever built, it would generate about 20 times more power than the Hoover Dam in America, enough to light up South Africa, the continent’s most industrialised country. Yet generating power is useful only if it can be sent to where it is needed, and in many parts of Africa electricity grids seldom stretch beyond big cities. Adding a house to the grid even in a compact country such as Rwanda typically costs about $2,000, which is more than the country’s average annual income per person. The APP reckons that expanding grid power across Africa to reach almost everyone would cost $63bn a year until 2030, compared with the $8bn a year that is being spent now.

Solar gain

Another set of innovations is offering to sidestep this problem with mini rooftop solar installations that can power a home, or slightly larger “micro-grids” that can light up a village. Rooftop solar systems usually consist of a small solar panel and a small rechargeable battery and controller which typically powers four lights, a radio and a phone charger. Most systems have a built-in connection to the mobile-phone network that allows the provider to switch it on or off remotely. Instead of shelling out $250 or so upfront for an entire system, customers can buy electricity for the equivalent of 50 cents a day using mobile money. If they run out of cash, their power is cut off until they are in funds again. Thanks to this new “paygo” model, venture capital is pouring into an industry that now has at least half a dozen significant firms. The largest of them, M-Kopa, has electrified more than 500,000 homes and is adding almost 200,000 more a year. Across the industry as a whole perhaps a million families now have rooftop power. At current rates of expansion, the total may double every 18 months or so.

Prices of small solar-powered lights fell by 80% between 2010 and 2015

Prices for these systems are also falling fast. The Global Offgrid Lighting Association reckons that prices of small solar-powered lights fell by 80% between 2010 and 2015. It forecasts that those for a large home system, including low-powered lights, television and radio, will fall by 45% between now and 2020.

The electrifying growth of rooftop solar energy is now sparking another round of innovation, some of which may in time travel back to the rich world. Azuri Technologies, a company based in Cambridge, England, is programming its systems to forecast how much power each household will use that evening. It then subtly adjusts the brightness of lights or the television to reduce power consumption on cloudy days.

The main problem with rooftop solar systems is that they produce only small amounts of power. They enable clinics to keep functioning at night and to keep vaccines cool, and small shops to stay open longer and offer chilled drinks. But they cannot run power-intensive machines such as welders or mills, which require much larger solar installations and bigger batteries. Still, in the past few years a growing number of energy-intensive businesses such as mines have been putting up solar panels to replace diesel generators. The IEA reckons that this can cut a firm’s energy costs by half.

These bigger systems are also beginning to play a role in powering villages with “minigrids”, which are much cheaper and easier to install than full-scale national power grids. Data on the spread of minigrids and their economic impact in Africa are scarce, but a study by the Rockefeller Foundation in India found that when minigrids were installed in villages, small businesses increased their sales by 13% and incomes rose across the area. “If you want to drive the productive use of electricity and move people up the economic ladder, then you need a minigrid,” says Deepali Khanna of the Rockefeller Foundation. The Smart Villages Initiative, which has brought together scientists from Cambridge and Oxford Universities to get minigrids adopted more widely in poor countries, found that once smallholder farmers have electricity, they quickly adopt a range of other technologies such as irrigation pumps and smartphones to get long-term weather forecasts. “You then soon find support industries springing up to feed this higher level of economic activity in the villages, together with a general increase in well-being,” says John Holmes, a co-leader of the initiative.

Minigrids have been relatively slow to take off because of their high capital costs, but several organisations are trying new business models to spread the expense. The Rockefeller Foundation is exploring whether mobile-phone companies can become anchor customers of minigrids. That would help to secure the finance needed to build the grid, but also to reduce one of mobile-phone companies’ biggest expenses: diesel for the generators that power their masts. By one estimate this accounts for as much as 60% of the cost of operating their networks in Africa. Minigrids can thus help to spread not just energy but, just as important, phone and internet connectivity.