Solar water heaters, also known as solar domestic hot water systems, are one of the most effective ways your household can cut down on its carbon footprint. Solar water heaters are very environmentally efficient because they do not rely on fossil fuels. Plus, they are a cost-effective option because the fuel they use is free.
How Solar Water Heaters Work
There are two types of solar water heaters: active solar water heaters that utilize circulation systems, and passive solar water heaters that do not use this system. Both types of solar water heaters include solar collectors and storage tanks.
Active Solar Water Heaters
Active solar water heaters use one or more pumps to circulate water and/or heating fluid in the system. Due to having more moving parts, these systems are a little more expensive than passive systems, but they also provide many advantages. With these systems, the storage tank can be situated below the collectors (solar panels), allowing more freedom in location of the tank and the possibility of using the preexisting storage tank in the home. The tank can also be hidden from view, unlike passive systems, and homeowners have more control over the system.
Direct circulation systems are active systems that circulate water through the collectors and into the home. These systems are best suited for mild climates. Indirect circulation systems circulate a heating fluid through the collectors, heating the water that then flows into the home. These systems are popular in freezing climates.
Passive Solar Water Heaters
Due to having fewer moving parts, passive solar water heaters are less expensive than active systems and require far less maintenance, but they are also not as efficient. Integral collector-storage passive systems have a tank that act as both a solar collector and water storage. These are only suitable for moderate climates, as much of the heat is lost at night. If you are considering going the passive route, be sure that your roof is able to handle 600-700 pounds of water.
Types of Collectors
There are three types of solar collectors used with solar water heaters. There are flat plate collectors, which most people consider “solar panels”; the aforementioned integral collector-storage collectors, which use one or more black tanks in an insulated box; and evacuated-tube solar collectors, which feature parallel rows of transparent glass tubes that are most likely to be utilized commercially.
Things to Consider Before Going Solar
- Determine the cost and efficiency of a solar water heater for your home.
- Evaluate your home’s “solar resource” – in other words, will the solar collectors get enough sunlight?
- Investigate local regulations, codes, etc. before installation.