Tips to select a Solar Water Heater.

We are blessed with Solar Energy in abundance at no cost. The solar radiation incident on the surface of the earth can be conveniently utilized for the benefit of human society. One of the popular devices that harness the solar energy is the solar water heater.

It consists of a collector to collect solar energy and an insulated storage tank to store hot water. The solar energy incident on the absorber panel coated with selected coating transfers the hat to the riser pipes underneath the absorber panel.
The water passing through the risers get heated up and is delivered the storage tank. The re-circulation of the same water through absorber panel in the collector raises the temperature to 80 degrees Celcius (Maximum) in a good sunny day. The total system with solar collector, storage tank, and pipelines is called solar water heater.

This are all technical aspects, but people normally don’t usually understand this unless they are a solar industry expert. The question still arises.

“Is Selecting a Solar Water Heater a problem?”

 What you need to know is a couple of important things, that will help you decide the kind of solar water heater that is best for you.

A)  What are the types?

        a). Flat Plate Collector Solar Water Heater 

        b) Evacuated Tube Collector Solar Water Heater.

B). What are the type of circulation?

There are two types of systems in use for taking the water from the Water Heater into your home –

     a).Thermosyphon Systems–  or a non-pressurized system. The Thermosyphon system does not have a water pump to take the water into your home and works on the principle of solar heat, and are simple and relatively cheaper. In this system solar water heater should be at lower height than main water tank.

     b). Forced Circulation Systems or a pressurized system.The Forced Circulation System uses a water pump to take the water into your home or institution. In this system solar water heater can be at lower height than main water tank. We use this system when solar water heater tank is at higher height then main water tank.

C) Which type of circulation is better? 

The Thermosyhon System is better for homes and smaller institutions it is cheaper to run as it does not require an addition pump.The Thermosyphon system needs good water which does not have high chlorine content.The Forced Circulation System is generally used for large institutions and larger developments.

 Both the Evacuated Tube Collector and Flat Plate Collector Solar Water Heater can be used with either a Thermosyphon System or a Forced Circulation System.

D) Which one has longer life span?

 The Flat Plate Collector Solar Water Heater is made of metal and has a longer life.The Evacuated Tube Collector  Water Heater uses glass as a component which does not have as a long a life as compared with Flat Plate Collector Solar Water Heater.

E) Do you have hard water problem in your area.

If the water in your area is hard and has more chlorine then the Evacuated Tube Collector Solar Water Heater is preferable as it does not get blocked due to scaling from the hard water. The Flat Plate Collector Solar Water Heater can be used with hard water, but it will need an additional heat exchanger unit. Both type of water heater can be used in hard water you just need to check what level of hardness the product can handle.

  • Soft Water: Water Hardness less than 300 ppm.
  • Hard Water: Water Hardness >300 ppm and <600 ppm
  • Extreme Hard Water: Water Hardness greater than 600 ppm.

F) What is the climatic condition in your area?

 In warmer regions both the Flat Plate Collector and the Evacuated Tube Collector Solar Water Heater perform equally well.However in colder regions where there is a chance of water freezing, the evacuated Solar Water Heater is preferred as they avoid the water freezing even during sub zero temperatures.Even the Flat Plate Collector  Water Heater can be used in colder regions but it will need anti-freeze which increases the cost.

Some Additional Tips:

1.Is your home or office is suitable for a solar water heater
You will need to install the solar water heater in a place (roof, open land, or anywhere else) which fulfills following conditions:
1. It gets direct sunlight
2. The place faces the South Eastern direction
3. It can hold the weight of the solar panels and the entire system

 2.To know what capacity solar water heater you need.
Its capacity is measured in LPD (Litre per day). Find out how many liters of hot water you use per day. Usually on an average each person uses 40-50 liter per day. So if number of members who are going to use water heater per day is 10, then use 500 LPD Solar water heater.
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