Expected payback periods for heat pumps and solar geysers

The electricity tariff increase in the past 5 years had a visible effect on the solar geyserpayback period of heat pumps and solar geysers, such that we can expect a 1.5-2 year return on investment (ROI) for heat pumps and a 3.5-3.7 year return on investment for solar geysers.

An investigation undertaken by the M-Tech Industrial (PTY) Ltd. and North-West University in 2010 suggests that you can expect a payback period of 1.3-3.1 years for a heat pump and 3.4-4.1 years for a solar geyser. However, the cumulated electricity tariff increase over the past 5 years is 112.6% accompanied by a cumulative inflation rate increase of 29.0% over the same period. This means that if the price increase of these water heating systems matched the inflation rate, the associated payback periods would have come down drastically, making it even more and more feasible.