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Selecting a Solar Water Heater: Know the Basics

Heating water takes up a significant amount of energy consumption for the average home. After all, hot water is a near constant daily need. We need it for showers, baths, laundry, washing dishes…and the list goes on.

In most homes that have hot water heating systems, you’ll find either a gas or electric heater. Some water heating systems are more energy efficient than others. For instance, tankless water heaters can cut back on energy use far much more than the traditional tank type models. That being said, an even more energy efficient and greener way to heat water is through solar. This technology harnesses radiant heat from the sun, which is free, limitless and emits no greenhouse gases when converted into energy. Yet, many people have been reluctant to install solar water heaters citing high setup cost as a major constraint. The truth is solar water heaters don’t come cheap and neither are these appliances ideal for everyone.

solar water heating

In the following article, we’ll find out how these systems work, the various models that are available, and factors that determine which type of solar water heater to install. The pros and cons of using solar energy to heat water will also be discussed to help you decide whether this is a worthwhile investment.


How Various Types of Solar Water Heaters Work

Solar water heaters may be configured in a number of ways depending on climate conditions of where they will be installed, building regulations, among other factors. However, the basic setup for these water-heating systems comprises of the following:

  1. A Solar Panel Or Collector

This is essentially an insulated panel with a dark interior that houses a series of tubes where water flows. Solar panels or collectors capture radian heat from the sun and use it to heat water. Collectors have to be placed in direct sunlight and they usually have a glazed, glass coating to improve heat retention.

  1. Storage Tank

Some solar water heaters have a storage tank for holding water.

Solar water heaters may be divided into two broad groups, namely passive and active systems. A passive heater leverages the force of nature to move water around the system. An active heater requires electrical pumps and controls to operate.

Passive solar water heaters may further be broken down into the following sub-categories.

  • Thermo-Siphon

This type of solar heating system separates the collector from the water tank. Water heats up as its moves through the collector. Once hot, it’s pumped into a storage tank through convection (the tendency of hot water to rise).

  • Batch

Batch collectors have no tubes. Instead, these solar water heaters have just one tank inside a collector. Water gets heated up right inside the tank then it is moved to a home’s pipes via gravity or natural convection.

Additionally, active systems typically fall into one of three groups:

  • Direct

In this system, electrical pumps and controls move water through the solar panel and into a storage tank.

  • Indirect

Indirect solar water heaters are exactly what they sound like – systems that transfer heat from the sun to water indirectly via a fluid medium. In this case, a fluid transfer medium such as antifreeze flows into the sealed tubing of a heat exchanger that is submerged in water. Water never mixes with the antifreeze, but it picks up heat from the fluid medium before being pumped into a storage tank.

  • Drainback

Much like indirect systems, drainback solar water heaters use distilled water as a heat transfer medium. These systems have a separate drainback tank for distilled water.

Solar water heaters are typically used in conjunction with a traditional heater. The reason for this is that weather conditions affect how efficient these systems can be.


Common Concerns to Keep in Mind before Installing a Solar Water Heater

solar heating systemWhen considering what type of solar water heater to install, your decision will be dictated by a number of variables. To begin with, you have to consider atmospheric temperature because areas with cold climates should not use batch, thermo-siphon, and direct-active solar systems due to the risk of freezing.

Active systems also require power to pump water through the solar heater. So, keep in mind that it will be impossible to heat water with these types of heaters if there’s an outage. In addition, solar panels need ample sun exposure in order to heat water adequately. If you do not have a mounting location that meets this requirement, some companies won’t consider you as a candidate.


Pros and Cons of Solar Water Heaters

The biggest drawback of installing a solar water heater is the high initial setup cost that. While sunlight may be free, the system required to harness solar energy and use it to heat water tend to be quite expensive. In fact, using solar to heat water will cost you more than buying a tanked or tankless heating unit.

However, the long-term savings that a solar water heater offers far outweigh the high initial installation costs. When using solar to heat water, your electricity bill can go down by up to 50% or more. The amount of potential savings largely depends on the climate of where you live.

Generally, you can expect more savings from solar water heaters when using them in places that receive a good portion of sunshine all year round. But if you live in areas where there’s cold climate or cloudy winters, there would be less fuel (sunrays) to power the solar water heater and consequently savings will be lower.

solar water heater 2

Choosing to use solar water heaters is good for the environment as well. Your hot water carbon footprint can reduce by half when using these units, which is a boon if you care about reducing global pollution.

Due to the high cost of installing a water heater that uses solar energy, adding a unit to your home also increases its value. So, if you plan to sell your home in future, you just might get back the money you invested into the solar water heating system.

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