Solar projects have traditionally relied on long-term, fixed-price contracts that give lenders predictable revenues. That is starting to change. More developers are now selling power directly into wholesale markets through corporate PPAs, green certificates and spot trading.

Most of the attention in wind energy goes to the turbines: taller towers, longer blades, bigger megawatt ratings. A wind farm’s economics, though, can depend just as much on what happens below ground.

Africa has some of the world’s best solar, wind and gas resources, but sun and wind alone can’t keep the lights on around the clock. Solar peaks from late morning to early afternoon, and wind tends to blow strongest in the early morning and evening.