Solar Home Standard Water Heaters

Solar Hot Water Systems

Solar water heating systems may cost up front, but freeing yourself from reliance on oil or gas can lead to major savings over time and a reduction carbon dioxide emissions. In warmer areas, solar heating can supply 90 per cent of a household’s hot water needs. This boom in solar water heating has encouraged manufacturers to enter the market, giving consumers a wide variety of branded and unbranded solar hot water systems to choose from.

A solar hot water system uses the sun’s warmth to provide hot water for homes and other buildings. Water flows in pipes through roof-mounted solar panels, warming up as it goes. It then flows onwards to the hot water tank to provide hot water for your taps and home appliances. A closed loop system warms up the water in the tank using a heat exchanger, which keeps the water from the solar panels separate from the water that you drink and wash with. Other open loop systems just direct warm water from the panels into the hot water tank. Because the water has to be driven up to the roof against gravity, solar hot water systems also require a pump to move the water through the pipes.

Solar panels are an essential part of all solar hot water systems. Flat panel collectors are one common option as they are simple to build and cheap to buy. An absorber plate is backed either by a length of pipe or a fully flooded chamber, and then both the panel and the pipes are sandwiched between two translucent panels to trap heat. Evacuated tubes are more complex and more expensive, but also collect heat more efficiently and heat water to higher temperatures. They are made up of small glass tubes suspended inside larger glass tubes with a layer of vacuum in between to trap heat. The inner tube is coated internally with light-absorbing material and attached to a connector plate that absorbs the heat and heats the water. The use of vacuum insulation makes heating more efficient and allows higher maximum temperatures.

Many solar hot water systems require a pump to force water up to roof level. While passive thermosiphon systems that rely on convection exist, they can be limiting as they require the hot water tank to be installed higher than the heating panels. Active systems use a pump, typically electric, to drive the water through the pipes. However, running the pump at full power constantly would be inefficient, so many pumps have multiple speeds and can be regulated by a control unit either manually or automatically.