Heating water for domestic use can be expensive because it requires a huge amount of electricity. Rather than relying on electricity, we have got another option, that is Solar Water Heater. It is a great way to reduce electricity costs associated with heating water. Solar Water Heater utilizes the solar heat radiations directly, which makes it more efficient and cost-effective. It can widely use in residential and industrial applications to reduces the water heating cost by 50% to 80% over electric or gas-fired water heaters. Thus solar water heater is often more affordable and offers a quick return on investment.
If you are planning to install one for your home, it is very important to gain a real understanding of a solar water heater system. There are various factors which must be considered while buying a solar water heater such as types, brands, cost and space required.
WORKING OF A SOLAR WATER HEATER
The solar water heater is based on ‘Black body heat absorption principle’. Sun rays make everything hot on which they strike directly. Main components of solar water heater are the collector and storage tank. A black absorbing surface (collector) absorbs heat radiations and transfers the heat to the water. Hot water collected in an insulated storage tank to prevent heat loss. Cold water circulates to the collector and back to the tank, the process continues automatically due to Thermosiphon effect. As the water heats up in the collector, it rises up naturally into the storage tank. Meanwhile, cooler water in the bottom of tank flows down to the collector. The phenomenon is called as natural Thermosyphon.
Water heater based on Thermosyphon does not any water pump, which saves the cost of water pump installation and electricity.
Based on the collector system, solar water heaters can be categorized into two types:
1. Evacuated tube system
Evacuated tube collector is made from multiple glass tubes that contain copper pipes at their core. Glass tube works as the green house, it lets enter the heat to tube but prevents from escaping. Water heated up in tubes and sent to a water tank. The cylindrical shape of tube ensures that it would collect maximum sunlight throughout the day and at all times in the year.
Evacuated tube systems are excellent for residential as well as commercial applications.
The effective life of collector can be up to 20 years, if reflective coating inside the tube is not degraded.
2. Flat plate system
Flat plate collector contains a dark-colored metal box with a glass or plastic insulated cover. Solar heat absorbed by the absorber plate and transferred to the water. Hot water stored in large insulated storage tank. Flate plate collector made of metal – mostly copper and aluminum, because both metals are good heat conductors. Though collector long lasting and low maintenance, more expensive than the Evacuated tube.
Capacity of solar water heater
The size of solar water depends on the volume of heated water required. Capacity measured in LPD (liter per day), which means that it can deliver 100 liters of hot water in a day at 60 C. Solar water heater available in 100 LPD, 150 LPD, 200 LPD, 250 LPD and 300 LPD sizes. For a family of 4 members, 100 LPD heater advised to meet daily hot water requirements.
Solar water heater price
Cost of solar water heater system depends on size, type of collector and of course brands (manufactures). Size is the dominating factor in price because bigger heater needs a larger storage tank and wider collectors.
We have gathered some price related data from leading solar water heater manufacturers in India. Please note that it is just approximate price to give you an idea.
|Capacity (in LPD)||Starting Cost of ETC system (in Rs)||Starting Cost of FPC system (in Rs)|
Government subsidies and other benefits
The subsidy scheme has been discontinued w.e.f 12.08.2014 onward, still, you can avail other benefits like a rebate on electricity bills, Yes you read it right. Some state electricity board provide additional discounts on monthly bills.
For example Haryana state electricity:
1. Rs 100/- per month for 100 LPD capacity.
2. Rs 200/- per month for 200 LPD capacity.
3. Rs 300/- per month for 300 LPD capacity.
for details visit www.hreda.giv.in.
Please note above benefits are for Haryana state electricity board consumers only. Benefits differ with state electricity boards, so make sure to check with your electricity board accordingly.
The solar water heater can be a smart investment to save money and environment. Let’s do some simple maths to understand how much electricity can be saved by the solar water heater in a year.
A 100 LPD water heater installed in a home can save 4-6 units of electricity/day depending on the usage of hot water and place of installation. On an average, it could be taken as 5 units/day. Maximum average saving with 300 clear days, therefore, could be taken as 1500 units/year.
Let’s try to understand the role of location in above calculation. Suppose in Shimla hot water requirement last for 300 days and in Gurugram it may be 100 days, therefore savings could be 1500 & 500 units per year respectively. On an average saving could be taken as 1300 units/year/100 lpd system.
Moreover, you can combine solar water heating with rooftop solar panels, if roof space allows. This way you can use electricity generated from the solar PV to top up the solar heated water to the temperature required. This combination of panels is the most efficient way of generating your energy requirements.
Please do read our article on Top 10 solar geyser manufacturers (companies) in India