Solar water heating (SWH) is the conversion of sunlight into heat for water heating using a solar thermal collector.
A solar water heater can save you money in the long run.
How much money you save depends on the following:
- The amount of hot water you use
- Your system's performance
- Your geographic location and solar resource
- The cost of conventional fuels (electricity)
- The cost of the electricity you use for your backup water heating system
Types of Solar Water Heating System
- Thermosiphon Systems. These systems heat water or an antifreeze fluid, such as glycol. The fluid rises by natural convection from collectors to the storage tank, which is placed at a higher level. No pumps are required. In thermosiphon systems, fluid movement, and therefore heat transfer, increases with temperature, so these systems are most efficient in areas with high levels of solar radiation.
- Forced-Circulation Systems. These systems pump water from storage to collectors during sunny hours. The storage tank can be located on the ground or pump room.
- Indirect Water-Heating Systems. In these systems, freeze-protected fluid is circulated through a closed loop and its heat is transferred to potable water through a heat exchanger with 80 to 90 percent efficiency. The most commonly used fluids for freeze protection are water-ethylene glycol solutions and water-propylene glycol solutions.
- Solar thermal system is designed to harness sunlight for its thermal energy (heat). This heat is often used for heating water used in homes, businesses, swimming pools, and for heating the insides of buildings (space heating).
- As the water is pumped through the collector the solar thermal collector will transfer the heat from the sun to the water to to be heated. Heated water then is pumped out of the collector and through a storage tank or a heat exchanger.
- Heat exchangers are usually comprised of copper, and are normally found inside a solar storage tank.
- The storage tank is an essential element of any solar thermal system, as it allows all the heat being generated by the solar thermal collector to be stored for use whenever it is needed.
Solar Heating Return of Investment
For example - 300 liters of hot water storage tank required electricity to heat from 30°C to 60°C :-
Q = cp m dT - 4.186kJ/kg°C x 300 kg x (60-30) / 3600 = 10.465 kWh
Given newest TNB tariff per month as follows:
TARIFF CATEGORY UNIT CURRENT RATE (1 JAN 2018)
Tariff A - Domestic Tariff
For the first 200 kWh (1 - 200 kWh) per monthsen/kWh21.80
For the next 100 kWh (201 - 300 kWh) per monthsen/kWh33.40
For the next 300 kWh (301 - 600 kWh) per monthsen/kWh51.60
For the next 300 kWh (601 - 900 kWh) per monthsen/kWh54.60
For the next kWh (901 kWh onwards) per monthsen/kWh57.10
10.465 kWh x 30 days = 313.95 kWh = 0.516 x 313.95 kWh = RM 162.00 x 12 months
= RM 1,944.00 (for water heating only)
Based on the above calculation, estimated return of investment is between 2 to 5 years
