How A Solar Water Heater Works


Water heating is a great place to begin cutting back on fossil fuel consumption. Water heating is very energy intensive, and solar offers a solution that can be implemented fairly easily in individual homes.

As a general rule, heating water accounts for 30% of most peoples’ energy costs.

There are a number of options for a solar water heater; from purchasing ready-to-roll systems to making your own.

The basic model is that the sun’s energy is used to heat water. The process is called solar-thermal – conducting the sun’s energy as heat, as opposed to photovoltaic – converting the sun’s energy into electricity.

How do solar water heaters work?

solar water heater

Roof Mounted Solar Water Heater – Cold water flows into the tubes, is heated by the sun, and flows out to an insulated cylinder.

A module of solar tubes is installed on a roof or sun-exposed area. Cold water passes through the tubes and is heated by the sun, flowing to an insulated cylinder once heated.

Alternate systems use chemicals such as glycol, which are easy to heat. The glycol flows through the solar tubes, then heats the water.

Most solar water heating systems require an electric powered backup heater known as a booster. The booster kicks in to further heat the water and kill any bacteria, or at night time and cloudy days when the system isn’t getting enough sun energy.

Some systems carry the water to a storage cylinder inside the house, whereas some storage tanks are outside (often connected to the solar module), or in the ground. The advantage of having the tank inside is better insulation. The advantage of outside is that installation is simpler and cheaper for retro-fitting.

There are also differences in how the water gets to the cylinder. Convection solar water heating systems use convection current principle – that hot water rises – to transfer hot water to the cylinder. This method stores the hot water above the module and doesn’t require any mechanics or electricity. Pump based systems use an electrical pump to transfer the water to the cylinder.

Buy solar water heaters or make your own?

Solar water heaters can be purchased as a package and installed by professionals or you can make your own.

The main advantage of a professional job is knowledge and experience; your solar water heater system will be tidy, installed with best practice, made from materials that have been tested and proven to last, be installed in the optimal spot for maximum sun exposure, and will likely come with some type of guarantee.

The downfall of using professionally made solar heating systems is expense.

There are large communities of people on the net who make their own alternative energy mechanisms, and many of them have instructions for building your own solar water heater.

It’s highly recommended you do some due diligence before diving in to either option. Installation is a big task so you only want to do it once.

Things to consider

Price: Never just go for the cheapest option, but have a look around and get a feel for prices, including installation and maintenance fees. Often sourcing locally is the best option as there’s easier access to follow up support, but have a look on the internet as well and get a broad gauge of the prices and packages available.

Kitset or pay for install and maintenance? If you’re an experienced tradesman you may be able to purchase from a company then install a solar water heater yourself. In this case you’ll be able to save a lot of money, but check with your dealer whether they offer product-only sales.

How much hot water do you need? A family of four uses a lot more hot water than a family of two, so make sure you’re thinking literage when you’re looking at your solar hot water options.

Solar company reputation: Take your time to get as much information as you can about your chosen solar hot water company. Look on a number of websites and read as many customer reviews as you can.

Your solar company should be happy to offer a free consultation before you commit. A good thing to consider is whether they can answer your questions without hassle. If they can answer your questions over the phone and without having to look things up every two seconds it’s one indicator that the staff have a good knowledge of solar and offer good customer service. If they tell you to just read their website it may not be a great indicator. Also remember to compare maintenance service and guarantees.

DIY solar reputation: Likewise if you’re building a DIY solar water heater, have a look around and scope out the best plans. Look for plans that have been used by many people and include good feedback. Join forums and learn from the experience of other alternative energy-ites. It’s also a good idea to discuss any plans with a builder, plumber or electrician, and research your local consent requirements.

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