Difference between a Solar Geyser and a Heat Pump

Solar Geyser Heat Pump
UNIT COST Higher capital upfront investment and installation costs Lower capital upfront investment and installation costs.
ELECTRICAL Works optimally when the sun shines, no electricty required. If it is overcast, the electrical back-up element kicks in to compensate for the lack of solar energy. Completely dependent on electricity to heat the water. Uses more electricity than a solar geyser due to its dependence on electricity however this usage per hour is low. A 5Kw heat pump uses 1Kw per hour, whereas a conventional 200 litre electrical geyser uses 200Kw per hour.
MAINTENANCE Routine maintenance similar to an electric geyser is needed on a solar water heater, but only on the valves and not on the system itself. Periodic checks are required to check and top-up (if necessary), or replace (depending on the system) the anti-freeze agent. Heat pumps require a lot of maintenance due to the constant moving parts. Maintenance on a heat pump not only requires the skills of a plumber or electrician but also that of an air conditioning technician.
EFFICIENCY Solar water heaters are more ideal for Gauteng winters where we have cold clear sky. Heat pumps are less efficient than a solar system in high radiation and low ambient temperatures.
SAVINGS A solar water heater can save up to 40% on your household’s water heating costs. Achieves 80% of the savings that a solar heated water can provide.
INSTALLATION Requires intricate plumbing. Relatively easy to install.
FITTINGS Requires a non-return valve, an isolating valve and a thermo blending valve. The thermo blending valve requires maintenance. Requires two isolatating valves and a strainer. The strainer must be cleaned periodically, especially on older homes with galvanised pipes.
INSTALLATION POSITION Typically mounted on roof, preferably North facing to achieve best sun coverage, however can be installed anywhere. Must be mounted not more than 10 meters away from the water storage tank. To ensure sufficient savings, the heat pump either needs to face north, east or west.
Can be noisy. Most noise generated after hot water consumption (at night, early in the morning).
WATER QUALITY The quality of water doesn’t influence the system. The Solahart system has a sacrificial magnesium protective anode and double ceramic lined tank prevents corrosion. A Solahart solar water heater also handles the issue of calcium carbonate better, as it can be easily scooped out during routine maintenance. Heat pump manufacturers do not warrant their systems if the hardness of the water is higher than a certain level. The calcium carbonate in the water solidifies and falls to the bottom of the tank. After a while, the sediment starts to block the heat exchanger.
LIFESPAN The lifespan of a solar geyser is 15+ years. The lifecycle of a Solahart solar water heater is 20+ years, the oldest system is 30 years old and still running. The lifespan of a heat pump is 5 to 10 years.