Types of Solar Water Heaters

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In today’s world, the majority of people are trying to do what they can to preserve the environment and be ‘greener’. As solar technology becomes more affordable, it proves to be an excellent choice for those who want to cut their energy bills. 

One of those methods of harnessing solar energy is getting a solar water heater. A solar water heater uses the sun’s energy to heat up water, which can later be used for things like showers, washing clothes, or even to make your tea. 

There are many types of water heaters that use solar power as a source for heating your daily supply of hot water. These systems differ in terms of how much hot water they provide per day, how much they cost, where you can place them, and if you need any special tools or knowledge in order to install them. 

In this article, you’ll learn about the different types of solar water heaters available, their benefits and disadvantages, how much they cost to install, their efficiency, and information on factors that can influence your decision if looking to purchase one.

What is a Water Heater?

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Before delving further into the different types of solar water heaters, we must first understand what a basic water heater is. A water heater is an appliance that heats up the water supply so that it is ready for use when you need it. 

There are three main types of water heaters: gas-powered, electric-powered and solar-powered. They all have their benefits and disadvantages.

If you are not familiar with the various types of water heaters, there are hot water storage tanks and tankless gas or electric models which do not store any hot water at all. They rely on a steady stream of cold water, which heats up quickly as it passes through the unit. 

The majority of homes in North America have their own conventional tank model where they keep large quantities of hot water for daily use. It works by heating up an enormous volume of water until it reaches its set temperature, which is regulated using a thermostat control device. Once the desired temperature has been achieved, the thermostat will shut off power to the heater element until the water cools down and falls below the preset level. 

However, solar water heaters are becoming more popular as they are both energy-efficient and cost-effective. They can provide a sufficient amount of hot water for an average household, depending on the size of the solar collectors. 

How Solar Water Heaters Work

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Solar water heaters rely on the sun’s rays to heat up water that is stored inside their storage tank. A small pump system moves heated fluid through pipes where it becomes ready for use whenever needed by the appliances throughout your home. 

A solar water heater can either be a fully passive, stand-alone system without any power source or an active unit that includes a backup heat exchanger and controls. 

Solar water heaters come in two different types: active and passive. 

Types of Water Heater – Active VS Passive

Solar water heaters can work in two different ways; active and passive. They both have their pros and cons, but the pros to using solar energy are that it is free (mostly), renewable, and eco-friendly. 

Active Solar Water Heating Systems

Active systems mean that they rely on electrical components or mechanical devices to work properly, such as pumps and valves. Despite needing additional parts like those which require maintenance, they also boast faster heating times because hot water is stored in tanks, rather than moved through the pipes passively with the sun’s power.

This type of system can be further classified into two different types: Direct circulation systems and indirect circulation systems.

  • Direct circulation systems: This type of solar water heater works by moving the fluid through a pump, transferring heat from the collectors to the storage tank. It’s only available as an active system and operates at a higher temperature than those found in indirect systems. 
  • Indirect circulation systems: Indirect circulation systems: this type of solar water heater does not use any electrical parts or mechanical devices like those found in direct circulation systems. Water runs through all components passively by using the sun’s power to heat the fluid traveling through the pipes. It will take longer for collected water to reach its maximum temperature since it is stored in a tank rather than directly heated.

Passive Solar Water Heating Systems

Passive units are free of these additional parts; instead, they operate through natural phenomena like gravity to get the job done. They are less expensive to purchase, but they have lower heating efficiencies due to the lack of a heat exchanger. Therefore, they heat up water more slowly since it must be warmed by sunlight that is absorbed into black-colored pipes where the fluid moves through. These pipes can absorb more heat than the fluid they contain since they are thicker and darker in color.

This type of system can be further classified into two different types: Integral Collector-Storage Passive Systems and Indirect Circulation Systems

  • Integral collector-storage passive systems: This this type of solar water heater works by using a black, made from iron or copper alloy, storage tank that is often placed on the roof to collect heat during the day. The stored water will stay warm throughout the night, giving it time to reach its maximum temperature by morning and not rely as much on the sun’s rays for heating after that point.
  • Thermosyphon systems: Thermosyphon systems are similar to integral collector-storage passive systems in that they both do not rely on electricity. Instead, this type of solar water heater uses gravity to move the fluid through the pipes passively. Thermosyphon systems are cheaper to make and can be used for small homes or single tap streams.

Different Types of Solar Water Heater Collectors

There are three types of solar collectors available that collect heat from the sun: Flat-plate, Batch collectors and Evacuated Tube.

Flat-Plate Collector: 

This collector is made up of a dark, flat metal panel on top with an insulated box underneath it; these two parts make up one complete unit. Water or glycol (a liquid mixture similar to antifreeze) passes through the metal plate while it is exposed to direct sunlight. The fluid then enters the insulated box where it is stored at high temperatures before being pumped into the home’s water heater for use.

Batch collectors: 

This type of collector can be placed at lower angles than flat-plate collectors since they are not exposed to the same amount of sunlight. This means it can collect heat for both day and night use. It is made up of three main parts: tubes filled with fluid, an insulating layer and a transparent cover that locks in the collected energy to warm the fluid contained within. 

Evacuated Tube Collectors:  

Evacuated tube collectors come in different types; however, all share these features: A glass or plastic inner tube that is vacuum sealed, metal absorbers inside to absorb sunlight, insulation outside that prevents heat loss and tubing around them to transport hot water (with solar powered pumps) into tanks. 

The Pros and Cons of a Solar Water Heater

There are little to no cons of getting yourself a solar water heater other than the initial cost of installing the system and maintenance or keeping an eye on the system for the upkeep of maximum efficiency with the fluctuations in weather. 

However, the many pros outweigh the cons in terms of the benefits they provide.

Pros of a Solar Water Heater:

The following are just to list a few: 

a) Prevention of pollution

Instead of using gas or fossil fuels to heat the water, it uses renewable energy from the sun so there is no additional pollution caused by its use. 

b) Saving energy

Since the water is heated for free from the sun’s rays, there is a dramatic decrease in energy costs. 

c) Minimal Maintenance/Longer lifespan 

Since it requires little to no maintenance, there is an extended lifespan as opposed to other types like electric or gas which need regular inspection and could break down easily. 

Cons of a Solar Water Heater:

The following are the cons mentioned above: 

a) Weather-dependent

The water heater is dependent on weather conditions. If it is cloudy, the efficiency decreases since there is no direct sunlight to heat the fluid inside the system.   

b) Higher initial costs

The initial cost of installing the solar water heater can be expensive; however, there are many government incentives to reduce this cost.

Conclusion

Solar water heaters are environmentally friendly and can benefit your house in many ways. The few disadvantages of owning one are minimal when weighed against the advantages it provides; especially for people who love to reduce their energy costs while conserving the environment at the same time.

We hope you were able to get familiar with all the different kinds of solar water heaters available for your household. Each will cater to a different need for households with different climate conditions, so decide which one best fits you by researching each type of solar water heater and what its benefits are.

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