A solar water heater (SWH) is a relatively cheap and easy way to start becoming energy independent and save some money. A solar water heater uses solar energy to warm the water used by your home, reducing your energy costs. Depending on the climate you live in and the efficiency of your model, a SWH can reduce your overall annual energy bill by 10-20%.
For information on pricing, read this article on the cost of installing a solar water heater for your home.
There are two types of systems a solar water heater can have.
An active system uses a pump to move water through the system. As such it requires a secondary energy source to power the pump. Active system allow for more design flexibility, like having the water tank indoors and out of sight. An active system may be necessary in colder climates where the water freezing is an issue.
Passive systems use no pumps or secondary power systems. Natural convection currents move the cold water from the tank to the solar heating panel, and the heated water from the panel to the storage tank for use. These systems are generally cheaper, but are less efficient, less reliable, and require the water tank to be located above the heating panels (this often means on top of the roof). Passive systems can have a separate water heater and storage tank, or they can be combined (known as a batch collector, as we will read about below).
Types of Collectors
There are various types of collectors a solar water heating system could have. All contain a fluid to transfer heat (often this is simply the water that is being warmed, but in colder climates it might be an anti-freeze solution).
Flat plate collectors are a panel with a glass or plastic top, a dark colored, sun absorbing bottom, and in-between them a series of pipes containing the fluid that transfers the heat.
Evacuated tubes are a series of tubes within tubes, where the outer tube absorbs and traps heat and the inner tubes contain the heat transfer fluid. It’s the most efficient, but most expensive method of solar collecting.
Batch collectors are water tanks that serve as both the solar collector and as water storage, contained within an insulated box to maximize energy absorption. They are probably the cheapest solar water heating system available.
Good luck and stay prepared!