Advanced solar water heating systems provide highest quality solar hot water and auxiliary heating equipment. Solar water heating systems are generally comprised of solar thermal collectors and a fluid system to move the heat from the collector to its point of usage.
Solar hot water system may use electricity which is used for pumping the fluid, and contain a reservoir or tank for heat storage . Solar water heating collectors have multiple evacuated glass tubes which heat up solar absorbents.
SYSTEM DESIGN REQUIREMENTS:
The type, complexity, and size of a solar water heating system is determined by –
1. Variation in temperature during the day–night cycle.
2. Variation in temperature and solar radiation between summer and winter.
3. The possibility of the potable water or collector fluid freezing.
A solar thermal system consists of solar collector, hot water cylinder, adjoining pipe work, adjoining pipe work and essential safety equipment.
Whole heat transfer fluid is pumped through the pipe to flow from the cylinder through the collector and returns to the cylinder.
Mains water is passed through the cylinder where it is heated prior to being plumbed into hot water system. A boiler may also be connected to the heat exchanger in the cylinder and can be used as a primary heating method during the winter and secondary in the summer. An immersion heater is used to heat the water further to ensure it has reached the minimum required temperature.
It consists of an equipment that is mounted on roof . This equipment is used for receiving the sun rays. These equipment are called solar collectors and they are of three types-
- Direct flow evacuated tube
- Heat pipe evacuated tube
- Flat plate
TYPES OF SOLAR WATER HEATING SYSTEM
- DIRECT & INDIRECT SYSTEMS
- PASSIVE & ACTIVE SYSTEMS
Direct systems are also referred as open loop systems that circulate water through the collectors this system is relatively cheap but can have the following drawbacks. They offer little or no freeze of protection, unless the collectors are freeze tolerant They offer little or no over heat protection unless they have a heat export pump. The collectors accumulate scale in hard water areas unless an ion exchange softener is used.
Indirect systems are also known as close loop systems. In this system heat exchanger is used this heat exchanger separates the portable water from the fluid and known as the heat transfer fluid that circulates the collector. The two mostly used heat transfer fluid are water and an anti freeze. Water mix that typically used non toxic propylene glycol after being heated in panel the HTF travels to the heat exchanger. In heat exchanger its heat is transferred to the potable water. This system is slightly more expansive, offer freeze protection and over heat protection as well.
The Passive systems rely on heat pipes to circulate waters or heating fluid in the system. It cost less and has extremely low or no maintenance, but the efficiency of passive system is significantly lower than that of an active system. It has two major concerns one is freezing and other is overheating.
- It has superior efficiency
- The storage tank can be situated below than the collectors
- The storage tank can always be hidden.
- Drain back tanks can be used
ADVANTAGES OF ADVANCE SOLAR WATER HEATING SYSTEM
- It is free and renewable source of energy
- This system use solar energy which help us to reduce our dependence on fossil fuels.
- Solar water heating system is cheap.
- They require overheating and freeze protection.
- In most areas they will require gas or electrical or other fossil fuel during winter period.
Solar hot water systems costs range from $800 to $12000