Some municipalities, most notably the City of Cape Town, offer a feed in tariff, meaning that you can sell excess energy back to the grid and recover some costs. However, not all municipalities offer this facility. Until all the municipalities are on board are best where they are designed to maximise your consuming all the power yourself and minimise feeding back to Eskom or the municipalities, mostly because the feed-in tariffs offered are far lower than what you would pay when you use grid electricity.