A Review of health hazards associated with rainwater harvested from green, conventional and photovoltaic rooftops

Abstract

The world is experiencing a decrease in the volume of global freshwater. Most countries are faced with both freshwater and energy crises. For these reasons, countries are encouraging the use of renewable energy systems such as photovoltaic (PV) modules/panels. Regarding water, there is a need to enhance domestic rainwater harvesting process in informal (low-income) settlements and rural areas. However, because of the contamination, such harvested rainwater may pose a health hazard to its consumers in instances involving photovoltaic roofs. When photovoltaic modules degrade, cracks and delamination may occur in some of the modules. PV modules have the potential, therefore, of producing and leaching toxicants/metals into the rainwater harvested from such PV panels. At a certain degree of contamination water may become non-potable since it can cause a problem upon consumption. This challenge requires a detailed review investigation to reveal the actual effect of the continuous use of the rainwater as mentioned earlier and its possible solution. To achieve this, a review of what has been done in this area is presented and analysed. This study combines the effect of contamination of rainwater harvested from multiple roof types, such as conventional roof, green roof, integrated roof and PV roof of newly installed panels. This study is vital in the sense that while the health impact of a newly installed PV system can easily be controlled by merely avoiding the use of rainwater harvested during the infant stage of its installation, the same cannot be said of the later stage, as perpetual avoidance may be impossible.