Solar Thermal Systems

 The easiest way of harvesting solar energy is converting it into heat energy.  It mostly uses the greenhouse effect to convert the sunlight into heat and store the heat in a closed chamber. The best things are that no pollution and no fuel required. The most common items that we use are mentioned below along with their working process.

Solar Cooker:

Three types of solar cooker explained below.

Box Type Solar Cooker:
It is a well-insulated box that has a double glass door and a mirror to reflect some extra light towards it. The light goes in through the double glass door and falls on the black surface inside. Due to the double glass door and insulated sides heat gets trapped inside. Thus the temperature rises inside the cooker.

ETC Tube Solar Cooker:

Evacuated Tube is used as the collector to contain the heat. Stainless steel or Aluminium reflector is used for focusing the light towards the tube. This parabolic reflector concentrates the light on a point or on an axis. By this method approx. 300 deg C temperature could be generated very easily. Evacuated Tube gives it extra heat collection capacity and due to the vacuum layer heat loss becomes very less.

Parabolic Solar Cooker:

Umbrella type parabolic reflector is used to focus the light to the pot. 

Solar Dryer:

Solar Dryer is a well-insulated chamber that has a fan to pull the water vapour out. There are mainly two types of dryer:

• Direct Dryer
• Direct Sun Light is used to dry the items. This type of dryer used outdoor mainly. 
• Indirect Dryer
• Sunlight falls on the collector then air is heated up. This hot air is then used to dry the items.

Solar Water Heater:

Solar water heaters are used to get 24 hrs hot water supply. Heat Collector is used to collecting heat from the sunlight. Puff insulated tank is then used to store the hot water. This tank has no partition between hot and cold water. Hot water stays on the top and cold water rests on the bottom. This is the reason every tank has a cold water intake point at the bottom side. Hot water outlet point and temperature meter connecting point at the top side. Depending upon the type of collector there are two types of water heater present.

• ETC: In Evacuated Tube Collector specially made copper coated glass tubes were used to convert the sunlight into heat and the water gets heated up from there. Every tube has a three-layer coating with a vacuum between the glass to reduce the heat loss.

• FPC: In Flat Plate Collector type system copper fins were used to convert the light into heat. The top side of the collector is made of tougfened glass to let the light in. The light falls on the couper fins that has a large surface area. These fins are specially coated with a mat black colour. As the light falls over the coper fins they gets heated up then this heat gets transferred to the water in the copper tube that is connected with the fins. Hot water goes towards the top and cold water takes its place from the bottom. Every collector has a lightweight aluminium body. The collector directly connected with the tank is called the primary collector. If required there is probation for an extra auxiliary collector. Standard collector size is 1m x 2m. Every collector is properly insulated from the back side to reduce heat loss.