Britain's renewables sector is set for significant growth in the coming years as demand grows for energy efficient technologies.An increasing number of tradesmen will need to up-skill and learn how to design and install these technologies by taking renewable energy courses but many are unaware of the new appliances on the market.One technology which is growing in popularity is rainwater harvesting systems which enable both direct and indirect feeds to property appliances, such as WCs and can be used for garden irrigation and watering. A standard rainwater harvesting system can provide a household with two thousand litres of stored water and vastly reduces the need for mains supplied water.Overall this system saves on your carbon footprint and offsets the cost of water usage in the property. The tank is installed underground, although above ground tanks are available. The system is relatively straight forward; it harvests water direct from the roof of the house, takes the water through a filtration process and stores it in the underground tank ready for use by the home owner. The water is pumped to the appliance on demand. The system also has a mains back up facility to ensure the appliance always has a water feed, even in times of drought. Solar Thermal drainback systems are also growing in popularity and more tradesmen should take renewable energy courses in order to understand how they work.Such systems provide hot water through absorption of solar irradiation into the panels surface, heating up the transfer fluid and then extracting that heat out of the transfer fluid and in to the hot water unvented cylinder via a high surface area coil.This is also linked to a combi boiler to show how it is possible to link renewable technologies with traditional gas combi boilers, which enable greater savings on the boilers use of gas. The boiler will only heat up the water if the solar temperature reached needs topping up. The solar system pre heats the water and reduces the need for the boiler to heat the water to higher temperatures. Once the water is at 60C in the cylinder the solar valve will recognise this and send the water straight to the tap, bypassing the need for the boiler all together. This is different to a pressurised system, where there is no drain back tank and the panel is directly linked to the unvented cylinder.