Solar water heater is not a one-size-fits-all solution. When searching solar water heaters, you need to make some decisions before making a final choice. From specific equipment decisions to warranty, knowing what to look for in quotations from different suppliers can save you money and make sure you have the right system for your home.
Solar Water Heater Size
What size solar water heating system do you want? It is the first thing that you need to take into consideration.
To figure out what size system to install, you need to determine how much hot water you want to cover with solar energy. In most cases, you will not be able to find a system that covers all hot water use 100% of the time. If you are willing to invest a little more money to buy more collectors or larger tanks, then a higher capacity system might be right for you. Conversely, if you want to use solar hot water to supplement your daily use, you can choose a system with one or two collectors.
Active or Passive Solar Water Heater
Active and passive solar hot water systems vary depending on how the water moves throughout the system.
The passive solar water heating system has an electric circulation pump that allows water to pass through the piping of the system. Passive systems are slightly more expensive and more complex to run, but the presence of a pump means you can run a solar hot water system all year round, even if it's cold outside. Therefore, they provide greater efficiency than active systems.
On the other hand, active solar hot water has no pump to move the water. Instead, these systems rely on an upward trend in convection and warm water. And they need to be lifted high and usually need to be supported by your roof. For older homes or properties with roofs that cannot support a lot of weight, an active system will not get the job done. They do tend to be slightly less expensive than passive systems, but they aren’t suited for properties in regions with cold weather.
Direct Or Indirect Solar Water Heater
If you choose to install a passive solar water heating system, you need to decide between direct and indirect settings. The direct system heats the water directly from the sun, while the indirect system uses different fluids to transfer heat from the collector and then heat the water.
A direct solar hot water system circulates water through your collector where it is heated by the sun. It works well in warm climatic conditions because the hot water passing through the pipeline has little chance of losing energy when surrounded by hot air.
In an indirect system, a transfer fluid circulates through a conduit in the collector, capturing heat and ultimately passes through a heat exchanger within the storage tank, where the capturing heat is released to heat up water in your tank. These systems are often more successful because they are more resistant to cold weather.
What type of solar collectors do you want in your system?
There are two options for solar collectors: flat plate collectors and vacuum tube collectors.
The flat plate collector is a commonly used solar hot water technology that has been used for decades. They are made of an absorbent sheet bonded to the internal conduit of the panel. Absorber plates are usually made of a piece of copper or aluminum, painted or chemically etched black to maximize energy absorption. The main advantage of their relative to the vacuum tube model is the price - the flat plate collector is usually cheaper than the vacuum tube collector. They perform poorly in cold weather and are ideal in the southern climate.
The vacuum tube collector is a new innovation in the solar water heating industry and improves many aspects of the flat plate collector by surrounding the absorber plate with a glass tube. The vacuum inside the glass tube acts as a strong insulator, making vacuum tube technology perform better than flat plate collectors in colder weather. They also collect heat more evenly throughout the day and heat the water to higher temperatures.
If you are a little bit overwhelmed by all the information above? Here we will give a simple and concise guide to choosing a solar water heating system.
If there are many people living in your household so you don't have a large budget, you can choose a thermosiphon active direct system solar water heater system is probably your best option considering overall cost and efficiency.
If you live in a cold area and do not want to spend time and money on maintenance, a passive indirect system makes the most sense and system can work normally over a wider range of temperatures.