Adding to solar's allure is the tumbling price of batteries, making it more economic for consumers to capture surplus electricity generated from their roofs rather than export it at a small fraction of the cost of buying power from the grid.

"With batteries now readily available on the market, many people are taking this opportunity to install both solar and batteries - or to upgrade the size of their existing solar systems," Warwick Johnston, managing director of consultancy SunWiz. "The price of solar has dropped low enough, and power prices are rising high enough, for this to make economic sense for many commercial operators, too."