Water Heater types comparison

Solar Geyser Instantaneous Gas Water Heater  Geyser (Conventional) Heat Pump
Main Feature Water Boiler connected to Sun heating panels Instantaneous Water Heater, heating water instantly as it flows through Water Boiler Heat collector system pump system with a geyser drum as reservior
Heat Source Sun and Electricity depending on size and make Liquefied petrolium gas  Electricity Ambient Air
Backup Power Generator Batteries (2 x size D) or UPS depending on make and model Generator Generator
System Components Solar Collectors Heat Exchanger (Aluminium heat collector with copper piping) Electric Element Tank
Tank with Electric Element Burners PRV & TP Valve Compressor
Direct Circulation Pump Gas and water connections Vacuum Breakers 4 Way Valve
Indirect Glycol Circulation PC Board (depending on model) Tray In roof
Brackets for Mounting Fan (depending on model)
Remote (depending on model)
Safety TP Valve on Drum Anti frost protection unit, High water pressure relieve, flame failure device, oxigin depletion sensor, overheating sensor (depending on model) TP Valve on Drum TP Valve on Drum
Maintenance Solar collector panels Glycol replacement according to supplier specs. Replace 2 x size D batteries depending on model Anode replacements to expand lifetime on drum Anode replacements to expand lifetime on drum
Anode replacements to expand lifetime on drum
Disadvantages Hot water limited to size of drum. Can cause water damage to ceilings if not properly installed Some models require replacement batteries to be replaced after a period ( 2 x size D), other require a UPS Hot water limited to size of drum. Can cause water damage to ceilings if not properly installed Hot water limited to size of drum. Can cause water damage to ceilings if not properly installed
Unit more costly compared to a Gas Water Heater, as it is limited to its drum capasity Unit more costly compared to a Gas Water Heater, as it is limited to its drum capasity Unit more costly compared to a Gas Water Heater, as it is limited to its drum capasity
Generating electricity with a genetator, in case of a power failure from Escom, to power the unit is expensive Generating electricity with a genetator, in case of a power failure from Escom, to power the unit is expensive Generating electricity with a genetator, in case of a power failure from Escom, to power the unit is expensive
Sunlight limited to time and weather Has to work continuesly, therefore high wear on unit
Still requires a high amount of electricity for heating element (depending on make and model) Still requires a high ammount of electricity for heating element  Still requires a high amount of electricity compared to a Gas Water Heater 
Still high on electricity demand
Advantages The sun will reduce energy consumption by reducing the temperature rise of ambient water You only pay for what you consume High pressure demand on tap at 600Kpa Consumes lower levels of electricity
Hot water supply only limited to ammount of gas availible
Higher Flow Rates per minute
Easy to maintain
Requires no water storage
Can easily be operated by a UPS or batteries depending on the model
Desired Water Temperature can be set, therefore saving energy
Saving water by more easily placing appliance closer to supply
Better control over energy consumption
No water damage on carpets or ceilings
Influences Is impacted by weather conditions Not affected by weather Not dependent on weather Not dependent on weather
Eskom Power grid dependant Site specific energy delivery Eskom Power grid dependant Eskom Power grid dependant
Not dependent on Eskom
Fan Forced Gas Water Heater (uses 40 Watts of elec.).          Conventional type (uses 2 x size D batteries)