Solar Hot Water systems vary from different equipment being used and how they operate. Tanks are used in active systems but are not required in thermo siphon systems. Open loop systems for instance have Integral Collector storage (ICS) which means the tank and collector is inbuilt.
Some systems are active in that they use moving parts like pumps and valves while others are passive meaning they use no mechanical or moving parts. The mounting style also varies from roof mount, ground mount to awning mount and wall mounts for some situations. Hot water systems also vary from climate to climate. For instance, Open loops are good for nonfreezing climates while closed loops are convenient for the tropical.
Types of Solar Hot Water Systems
There are various types of solar hot water systems and below those are mentioned:
Progressive tube unit: Progressive tube unit is modeled after the ancient method of the integral collector in which a tank was painted black to absorb heat then insulated to retain heat. This is the simplest and oldest. It Uses 4 inch copper tubes and fins. It is advantageous in that it extracts more of the suns energy and avoids re radiation. This system is popular in home built units, cheap and simple. It is also made from recycled material
Thermo siphon system: This is the most popular system worldwide. It works on the principal of heat rising. Water is heated, expands and rises as the sunlight strikes and fins inside a collector box in a natural convective process. It uses lesser energy since it has a natural way of moving heat for storage use. Good because hot water can be used anytime. It is easy to install and does not require frequent servicing. This gives it a simple and good efficiency. It does not need electricity so it cannot be affected by blackout. But strict guidelines must be followed in installation for smooth unrestricted flow.
Three season system: This system of uses hot water for 3 seasons then drains it for the fourth. It however assumes the owner will have an alternative energy option. It can use the existing water as a backup, hence is inexpensive and requires only a small pump. Again it requires the owner to be there when the weather is cold since it is not freeze proof.
Closed loop drain back System
This type works best even on hottest and coldest climates and can go up to 20 years without needing to be serviced. It drains water back to the ground, it is Simple, versatile and freeze proof but wastes a lot of energy in the process
Active closed loop System: It is freeze proof and has quality components but is complex and has valves pumps and various controls. This gives it a need for periodic inspection and control. It may also not work in blackouts.
A summary of the classification
In brief, solar hot water systems are made up of tanks and solar collectors. These are either active or passive. Active in that they have circulating pumps and controls and passive have none. The other components are what determine a manufacturer's classification of these facilities. With every new model, comes a newer form of classifying them. But this is the basic classification.
A solar heating system if correctly installed returns the investment of installation costs. This will save you the hot water electricity bills which can be quite high and income consuming. The client and the situation often dictate the system chosen. Whatever the system type used, hot water is a necessity in everyone's home. How to get the water heated is a solution offered by these solar hot water systems.