Since the start of sharp electricity tariff increases in 2008, South African household demand for electricity has not been significantly affected. However, the combination of economic realities and ongoing electricity tariff increases will eventually compel households to reduce their electricity usage. This research explores the ability of South African households to make alternative-energy and/or energy-efficient investments in two tariff increase scenarios. It is found that middle-income households are the most vulnerable to rising electricity tariffs, due to their limited ability to invest in technologies that would significantly reduce their electricity usage, yet they are unlikely to opt for the alternatives used by low-income households. Assuming that 20 per cent of households that can afford to invest in particular technologies do so, then around one quarter of total residential electricity sales in South Africa could potentially go off-grid in the base case tariff scenario by 2030.