BRE DG532/4 PDF

Introduction

Solar thermal systems are designed to convert sunlight (solar radiation) into useable heat energy, usually in the form of domestic hot water. Solar collectors (also commonly referred to as ‘solar thermal panels') are positioned where they will be exposed to the sun's rays. Generally speaking a heat transfer fluid and pump move the collected heat to a hot water storage tank, where it can be distributed throughout a building as it is required, although some systems are designed to circulate the fluid by convection and so do not incorporate a pump. Because the fuel source (in this case the sun) is not depleted by this process, solar thermal systems are considered a source of renewable energy.

Traditional water heating systems commonly use fossil fuels as an energy source. Even boilers powered by electricity draw the required energy from sources currently dominated by fossil fuel power stations. Fossil fuels are carbon based; heat is generated through combustion, which also produces carbon dioxide (CO₂). The CO₂ is generally released into the atmosphere and is considered to be a ‘greenhouse gas', which contributes to climate change.

In contrast, solar thermal systems produce no CO₂ during the conversion of sunlight to heat energy. Systems that use pumps to move the heat transfer fluid may use some fossil fuel-derived energy to create the kinetic energy required, although solarpowered pumps are sometimes used. Carbon-based fuels are also likely to have been utilised in the manufacture of system components.