Home water heating proves to be a much more expensive process as compared to using a solar hot water (SHW) system. In fact, investing in a SHW system is considered as a second choice by many once you have invested in a home.
There are several types of SHW systems including Batch Water Heating System, Thermo-siphon system, Open-loop direct system, Pressurized Glycol system and Closed-loop Drain back system that are currently available in the market. They are briefly described here.
· Solar Batch Water Heaters, also called Integrated Collector Storage type, are a ‘One Unit’ system where collector and the storage tank form a single unit. Cold water in well insulated glass or porcelain cover is placed in the sun facing the south. While cold water is piped to the bottom of the tank, hot water is collected from the top. As the water in this process is heated directly, this is an example of open-loop system and as no pump is used to conduct the water from the collector to the end use, this may be termed as passive. Solar Batch Heaters are comparatively cheaper and so are widely used in ‘non-freeze’ areas.
· Solar Thermosiphon Water Heaters are based on the principle that hot water always rises to the surface while cold water always goes down. One of the advantages of the Termosiphon system over the Batch Heaters is that, the solar heat is well contained in thoroughly insulated water tanks and so hot water becomes available at night when the sun is no more there. Here the tank is located directly over the collector.
· Open-Loop Direct System Water Heaters are the simplest form of active systems ever built. These are called active since small 10 watts circulatory pumps powered by 10-watt PV modules are involved here. Otherwise, these consist of standards electric water tanks and 40- square-feet solar thermal collectors. Under normal conditions, the tank merely works as a storage tank for pre-heated water that feeds the back-up water heater.
· Pressurized Glycol System is a closed-loop system where the incoming water is conducted to the solar storage tank and not into the collectors. Water mixed with antifreeze (Glycol) is allowed to circulate from the collectors through a coil of pipe in the solar tank which is then piped back through the collectors. The water in this case is heated by heat transfer process, coming in contact with the pipe.
· Closed-Loop Drainback Systems are effective and reliable and they work for years without needing any maintenance. The heat transfer fluid is distilled water which is stored in a 10-gallon reservoir tank. When the system is turned on, it automatically turns a pump on that circulates the distilled water back through the collector and the heat exchanger, conducting heat to the water in the solar tank. As the system is turned off, it turns off the pump, too, causing the distilled water to drain back into the reservoir.
Getting a solar system for water heating makes a lot of sense because it is sure to save you a lot of money on your power bills. An alternative energy, solar power is eco-friendly too. You can install a solar power system but you need to get informed on the best place to set it up, learn about installing and wiring the system, and also know about the sources of cheap parts and batteries. You will also need to know about the safety precautions.