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Solar hot water refers to water heated by solar energy, a renewable energy source derived from the sun. This process involves thermal collectors, often called solar panels, which absorb solar energy to increase the temperature of the water. The heated water is then stored in a reservoir tank for future use. Solar hot water systems are utilized for a variety of purposes, including domestic and commercial water heating, contributing to heating and cooling systems, and providing process heat for industrial applications.
In residential settings, solar hot water systems are typically installed in one of two configurations. The "close-coupled" or "thermosiphon" setup integrates the thermal collectors with the hot water storage tank on a rooftop, allowing heated water to rise naturally into the tank. Alternatively, the "split system" separates the thermal collectors from the storage tank, requiring a pump to circulate water between the collectors and the tank. This configuration provides more flexibility in system placement and is often used when roof strength or aesthetics are considerations. [1]
Solar hot water systems are designed to reduce energy consumption, a significant source of greenhouse gas and carbon emissions; If the state of Victoria switched from electric to solar hot water, Australia's total greenhouse gas emissions would be cut by 20%. [2]
The penetration of solar water heaters in the Australian domestic market is at about 4% or 5%, with new dwellings accounting for most of the sales. [3] [4]
During the 1950s, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) carried out world leading research into flat plate solar water heaters. [5] A solar water heater manufacturing industry was subsequently established in Australia and a large proportion of the manufactured product was exported. Four of the original companies are still in business and the manufacturing base has now expanded to 24 companies.
Heating of water is the largest single source of greenhouse gas emissions from the average Australian home, accounting for around 28% of home energy use (excluding private vehicles). The Australian government estimates that installing a climate-friendly solar-powered hot water system could help households save $300 to $700 of electricity bills each year. [6]
The solar hot water rebate program [7] for financial year 2009 offered a $1,600 rebate for the installation of solar powered hot water systems.
The rebate can be collected once the installation has been finished, if the household meets the necessary requirements stated below:
Once the system is installed, the applicant has up to six months to submit the application form with the purchase receipt attached to it.
The mandatory renewable energy target [8] scheme was created by the Australian government to mandate energy retailers to the usage of renewables. Each solar heating system is given a certain number of RECs depending on how effective it is and in which of the four climate zones [9] one resides. Each zone is associated with a number of postcodes ranging across the whole continent.
Once issued, the RECs can be sold to energy retailers. While the market value of RECs is subject to variation, even residential-sized installations—depending on the current market conditions and the performance of the installed unit—often amount to payments of $900 or more. [10]
The ACT Energy Wise program, [11] run by the ACT Government, offers rebates to house owners or tenants that undertake energy saving improvements for at least $2,000 to their residence, such as insulation, inserting double glazed windows, installation of solar, or gas or electric heat pump water heating systems.
Only the first $1,000 of the cost of the installation of the water heating system (which replaces the existing electric heating system) can be used to calculate the $2,000 to be used on improvements. This means that to receive the rebate, the householder needs to spend another $1,000 on additional energy savings. [11]
To be eligible the rebate of $500 the householder/tenant must:
The New South Wales (NSW) Residential rebate program, [12] running from 01/10/2007 to 30/06/2009, offered all house owners in NSW a rebate on systems that were replacing existing electric hot water systems.
More efficient systems that emit less greenhouse gas eligible for more RECs (Renewable Energy Certificate) generated a higher rebate.
Solar or heat pump hot water system, eligible for: | Rebate in $ |
---|---|
20-27 RECs | 600 |
28-35 RECs | 800 |
36-43 RECs | 1000 |
44< RECs | 1200 |
5-star< gas hot water system | 300 |
Power and Water Corporation, the principal water and electricity supplier in the Northern Territory, offers an REC buyback scheme on installations of solar water heaters. [13] The buyback must be applied for and assigned less than one year after the installation. [13]
The Queensland Government's solar hot water rebate scheme finished on June 30, 2005. [14]
No state rebates are offered at the present[ time needed ]; however, the Queensland government in 2007 announced the phasing-out of electric hot water systems commencing in 2010. [15] From 2010, Queenslanders who needed to replace their household hot water system due to breakdown were no longer able to install electric systems and instead had to choose from gas, solar or heat pump options. Prior to this, the Queensland government had already banned the installation of electric hot water systems in newly constructed houses, a law which came into effect on March 1, 2006. The ban on electric hot water systems was repealed on January 1, 2013 and currently Queenslanders are permitted to install electric hot water systems. [16]
The Brisbane City Council offered a rebate of $400 from August 30, 2008 to June 1, 2009.
In accordance with the South Australian Government rebate scheme, [17] starting January 7, 2008, all installations or replacements of a water heater must be a low-greenhouse one. [18] The rebate scheme is aimed to give less fortunate people a financial incentive to use gas, heat pump or solar energy to heat water.
To be eligible for the $500 [17] rebate, the householder has to hold at least one of the following concession cards:
Following to the installation, the householder has up to three months to send in the application to receive the rebate if a criterion listed below is met.
The water heating system does not replace the existing one:
New system | No natural or LPG gas access | Gas access (natural or LPG) |
---|---|---|
Gas solar | Yes | Yes |
Electric solar or heat pump | Yes | No |
Electric or gas storage/instantaneous | No | No |
The water heating system does replace the existing one:
New system | Gas | Solar gas | Electric element/solar, heat pump | Other types (oil, combustion…) |
---|---|---|---|---|
Gas solar | Yes | Yes | Yes | Yes |
Electric solar or heat pump | No | No | Yes | Yes |
Electric or gas storage/instantaneous | No | No | No | No |
No rebates other than the Federal Government's are offered by the Tasmanian Government at the moment[ year needed ].
Sustainability, Victoria’s solar hot water program, [19] sponsored by the Victorian government, offers rebates to householders who have installed a system that abides the following criteria:
New houses and buildings can get a rebate by selling the RECs their system is eligible for. The Commonwealth government is also offering a $1,000 rebate for the replacement of electric water heating.
Residential and community buildings:
Installation situation | VIC gov rebate $480–1500 | Commonwealth Gov rebate $1000 | RECs eligible |
---|---|---|---|
Replacing natural gas or LPG WH w/ gas-boosted solar system | Yes | No | Yes |
Installing SWH as preheater to an existing natural gas or LPG WH | Yes | No | No |
Adding solar panels to an existing off-peak electric WH either with a pump or by thermosiphon as a retrofit kit | Yes | No | No |
Replacing a wood or briquette WH w/ gas-boosted or electric solar system | Yes | No | Yes |
Replacing an electric WH w/ gas-boosted or electric solar system | No | Yes | Yes |
New homes and buildings installing a gas-boosted or electric solar system | No | No | Yes |
Existing buildings requiring a custom designed system for a large hot water load | Yes | No | No |
Commercial buildings:
Installation situation | VIC gov rebate $480–1500 | Commonwealth Gov rebate $1000 | RECs eligible |
---|---|---|---|
New or existing building installing SHW | No | No | Yes |
An installation of an environmentally friendly, gas-boosted solar water heater that replaces a previous water electric heating system is eligible for rebate from the Government of Western Australia. [20]
System | Rebate in $ |
---|---|
Natural gas-boosted solar water heaters | 500 |
Bottled LP gas-boosted solar water heaters used in areas without reticulated gas | 700 |
An autonomous building is a building designed to be operated independently from infrastructural support services such as the electric power grid, gas grid, municipal water systems, sewage treatment systems, storm drains, communication services, and in some cases, public roads.
A heat pump is a device that uses work to transfer heat from a cool space to a warm space by transferring thermal energy using a refrigeration cycle, cooling the cool space and warming the warm space. In cold weather a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in warm weather. As they transfer heat rather than generating heat, they are more energy-efficient than other ways of heating or cooling a home.
Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.
Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential and some industrial applications.
A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning systems, which can both cool and warm interior spaces.
Microgeneration is the small-scale production of heat or electric power from a "low carbon source," as an alternative or supplement to traditional centralized grid-connected power.
Electric heating is a process in which electrical energy is converted directly to heat energy. Common applications include space heating, cooking, water heating and industrial processes. An electric heater is an electrical device that converts an electric current into heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators.
Renewable heat is an application of renewable energy referring to the generation of heat from renewable sources; for example, feeding radiators with water warmed by focused solar radiation rather than by a fossil fuel boiler. Renewable heat technologies include renewable biofuels, solar heating, geothermal heating, heat pumps and heat exchangers. Insulation is almost always an important factor in how renewable heating is implemented.
An air source heat pump (ASHP) is a heat pump that can absorb heat from air outside a building and release it inside; it uses the same vapor-compression refrigeration process and much the same equipment as an air conditioner, but in the opposite direction. ASHPs are the most common type of heat pump and, usually being smaller, tend to be used to heat individual houses or flats rather than blocks, districts or industrial processes.
A ground source heat pump is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through the seasons. Ground-source heat pumps (GSHPs) – or geothermal heat pumps (GHP), as they are commonly termed in North America – are among the most energy-efficient technologies for providing HVAC and water heating, using far less energy than can be achieved by burning a fuel in a boiler/furnace or by use of resistive electric heaters.
A solar combisystem provides both solar space heating and cooling as well as hot water from a common array of solar thermal collectors, usually backed up by an auxiliary non-solar heat source.
Renewable energy in Australia includes wind power, hydroelectricity, solar photovoltaics, heat pumps, geothermal, wave and solar thermal energy.
A home fuel cell or a residential fuel cell is an electrochemical cell used for primary or backup power generation. They are similar to the larger industrial stationary fuel cells, but built on a smaller scale for residential use. These fuel cells are usually based on combined heat and power (CHP) or micro combined heat and power (m-CHP) technology, generating both power and heated water or air.
The use of solar energy began in Israel in the 1950s with the development by Levi Yissar of a solar water heater to address the energy shortages that plagued the new country. By 1967 around 5% of water of households were solar heated and 50,000 solar heaters had been sold. With the 1970s oil crisis, Harry Zvi Tabor developed the prototype of the solar water heater now used in over 90% of Israeli homes. There are over 1.3 million solar water heaters installed as a result of mandatory solar water heating regulations.
The Renewable Heat Incentive is a payment system in England, Scotland and Wales, for the generation of heat from renewable energy sources. Introduced on 28 November 2011, the RHI replaces the Low Carbon Building Programme, which closed in 2010.
South Australia is a leader in utility-scale renewable energy generation, and also produces gas and uranium for electricity generation. Gas production is mostly concentrated in the Cooper Basin in the state's north-east. Gas is delivered from these fields by pipeline to users interstate and to Port Adelaide where it fuels three separate gas-fired power plants. Uranium is also mined in South Australia, though nuclear power generation is prohibited nationally. The Olympic Dam mine is the world's single largest known deposit of uranium and represents 30% of the world's total uranium resource. Many utility-scale wind farms and solar farms have been commissioned during the 21st century and geology with potential for geothermal energy has also been identified but is yet to be developed.
Approximately 44% of primary energy is from renewable energy sources in New Zealand. Approximately 87% of electricity comes from renewable energy, primarily hydropower and geothermal power.
Tankless water heaters — also called instantaneous, continuous flow, inline, flash, on-demand, or instant-on water heaters — are water heaters that instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil unless the unit is equipped with an internal buffer tank. Copper heat exchangers are preferred in these units because of their high thermal conductivity and ease of fabrication. However, copper heat exchangers are more susceptible to scale buildup than stainless steel heat exchangers.
A storage water heater, or a hot water system (HWS), is a domestic water heating appliance that uses a hot water storage tank to maximize water heating capacity and provide instantaneous delivery of hot water. Conventional storage water heaters use a variety of fuels, including natural gas, propane, fuel oil, and electricity. Less conventional water heating technologies, such as heat pump water heaters and solar water heaters, can also be categorized as storage water heaters.
Home energy upgrades from public utilities are added home energy efficiency and renewable energy features planned or installed by public utilities. Help from a public utility can make it easier for a homeowner to select, install or operate climate-friendly components. The utility might assist with coordinated use of utility-supplied energy, building features, financing, operating options and neighborhood supplied energy.