What is Solar Hot Water?
Broadly speaking, solar hot water is water that is heated using the energy from the sun. Not to be confused with solar electricity (photovoltaic or PV solar), solar hot water is one of the best ways to reduce energy consumption in the home. The energy used to heat domestic hot water in the average Australian home is generally around 1/3 of all energy used.
In most cases, a collector or panel is placed on the roof and gets hot when the sun shines on it. Cold water is passed through the hot collector and is heated.
Solar hot water systems are generally coupled with a storage tank that holds the heated water until it is needed by the house. In most cases, solar storage tanks operate on the principle of 'Stratification'.
Types of Solar Hot Water Systems
There are many types of solar hot water systems avaialble, however the most common systems in Australia are:
Split System: Where the collector is mounted on the roof and the tank is located at ground level. Cold water is circulated from the bottom of the tank to the roof where it is heated and returned to the middle of the tank. This cycle is repeated while the sun is shining. Coupled with super-efficient Evacuated Tube technology, you can achieve significant savings.
Preheaters: Where a solar collector and storage tank that does not have a booster is connected to an existing hot water system. Hot water from the solar storage tank is fed into the cold inlet of the existing hot water tank. Because the water entering the existing hot water unit is already hot, it doesn't require as much energy to heat the water.
Retro-fits: Where a solar collector is connected directly to an existing hot water unit. To maximise the savings, the existing hot water unit should be connected to an off-peak tariff, or to a timer that avoids conflict with the operation of the solar heating.
Thermosyphon system: Where both the tank and collector are located at roof level. Water is heated in the solar panel and rises into the middle of the storage tank.Cooler water in the bottom of tank is pushed out to the bottom of the collectors. This cycle is repeated while the sun is shining.
What solar hot water system should I choose?
There are many considerations to make when choosing a solar hot water system. Learn more about buying a solar hot water system.
What is Stratification?
Stratification is a layering effect created by water of different temperatures within the solar storage tank. Stratification is caused by hot water (which is less dense) rising to the top of the tank, thus the top of the tank has hot water in it (for delivery to the house) and the lower part of the tank contains cold or warm water that is subsequently heated using the solar collector.
When the sun is shining and the collector on the roof is hot, cold water is drawn from the bottom of the storage tank, is passed through the collector and is returned to the middle of the tank and stratifies. Solar collectors are more efficient when they are heating cold water, thus the excessive mixing of hot and cold water can reduce the efficiency of the solar hot water system.
High quality solar storage tanks are designed to minimise the mixing of hot water and cold water.
A well designed solar storage tank will reduce mixing and will therefor maximise both the performance of the whole system and the quality of water coming out of your tap.
You can be confident that with an Endless Solar storage tank that you'll get plenty of usable, free hot water from your tank. |
