Heat pumps are a viable alternative to solar geysers because it is relatively easy to install and can still provide you with an enormous energy saving. Because the heat pump does not require direct sunlight to work, you might even save more money that a solar geyser in winter months.
Heat pumps work on the same principle as a air conditioner (only in reverse) in that it collects the solar heat from the surrounding air and then uses that to heat up the water that circulates through it.
With up to 75% of the energy required to heat the water coming from the surrounding air, heat pumps can offer you significant savings to your monthly electricity bill. The remaining energy requirements must be supplied by normal electricity.
Unlike solar power, heat pumps are more affected by ambient temperature than direct sunlight. It is therefore possible for the heat pump to still work efficiently on a cloudy day with a relatively high ambient temperature.