SOLAR POWERED WATER PUMP 1
Solar Powered Water Pump Automatic Cooling System for the Panels
Most solar PV installations are rated to perform most efficiently at about 250C. When their surface temperatures go beyond this value, their efficiency is reduced continuously for every subsequent rise in temperature. To prevent such a scenario, the solar modules need to be cooled from time to time. This can be done by connecting the panels to a water supply which cools them whenever they overheat. This paper details how such a cooling system can be implemented.
In the schematic above, the manner in which the cooling system works is shown. The entire process begins at the solar panel, whose surface becomes heated when the solar rays strike it. It is connected to temperature sensors which detect how hot the panels get. These sensors are made of thermistors positioned on the panels in such a manner that they will receive sunlight when the panels receive it and will also be shaded alongside the panels when the sun sets. This ensures that the temperature that it records is accurate at all times since the entire cooling process and hence the efficiency of the panels depends on this dataset. It continuously records the temperature and sends this value via a signal to the control unit. The unit checks if this value exceeds the maximum allowable degree and by how much. It then sets the amount of charge to be passed to the battery from the solar panel through the charge controller. The higher the excess temperature is, the higher the quantity of charge passed. Consequently, this determines the amount of energy that the pump is supplied with. The cooling rate is also accelerated if the amount of water being pumped per unit time is higher. In this way, the system is automated and it can trigger or stop cooling at any point in time.
In the meantime, cool water flows from the source tank to the pump where it is pushed towards the solar panel. The force with which it is pushed and hence the quantity supplied is dependent on the quantity of energy the pump has been provided with by the battery. The water flows along the pipes within the panel and cools it while it gets warmer. These pipes are located within the panel and subdivided into rivulets in between the individual cells. The water gets warmed as it flows along these rivulets and which finally combine into one major pipe. The manner in which the water cools the cells is in principal quite simple. The cells are heated directly by the sun rays and are therefore warmer than the water inside the rivulets/pipes, heat flows from the cells and into the pipe and hence resulting in a cooling effect. This is further aided by the fact that these pipes are made of metals which effectively conduct heat away from the cells and into the cooling water. When the water has circulated across the entire panel and cooled each cell, it is drained into the storage tank by way of the main pipe. The warm water in the storage tank can then be used for a variety of household activities including bathing and heating if it is hot enough. However, since this is a continuous process, it can be allowed to cool. The storage tank is also connected to the pump and hence supplies the cooling water to the panels once its temperature is low enough.