Solar water heating ( SWH ) is the conversion of sunlight to heat for heating water using a solar thermal collector. Various configurations are available at varying costs to provide solutions in different climates and latitudes. SWH is widely used for residential and industrial applications.
The collector facing the sun heats the working fluid that goes into the storage system for later use. SWH is active (pumped) and passive (convection-driven). They only use water, or water and fluids that work. They are heated directly or through a light-centered mirror. They operate independently or as hybrids with electric or gas heaters. In large-scale installations, the mirror can focus sunlight onto smaller collectors.
The global solar summer market is dominated by China, Europe, Japan and India, although Israel was one of the first countries to require the installation of SWH in 1980, leading to a thriving industry.
Video Solar water heating
History
Recording of solar collectors in the US dated before 1900, involving a black painted tank mounted on the roof. In 1896 Clarence Kemp from Baltimore closed a tank in a wooden box, thus creating the first 'batch water heater' as it is known today. Frank Shuman built the world's first solar thermal power plant in Maadi, Egypt, using a parabolic trough to power a 60-70 horsepower engine that pumps 6,000 gallons of water per minute from the Nile to adjacent cotton fields.
Flat plate collectors for solar water heaters were used in Florida and Southern California in the 1920s. Interest grew in North America after 1960, but especially after the 1973 oil crisis.
Solar power is used in Australia, Canada, China, Germany, India, Israel, Japan, Portugal, Romania, Spain, UK and USA.
Mediterranean
Israel, Cyprus and Greece are the per capita leaders in the use of solar water heating systems that support 30% -40% of homes.
The flat plate solar system is refined and used on a large scale in Israel. In the 1950s a shortage of fuel caused the government to ban hot water between 10 pm and 6 am. Levi Yissar built the first prototype of Israeli solar water heater and in 1953 he launched the Nerya Company, Israel's first heated solar water producer. Solar water heaters are used by 20% of the population in 1967. After the energy crisis of the 1970s, in 1980 Israel needed the installation of solar water heaters in all new homes (except high towers with insufficient roof area). As a result, Israel became the world leader in the use of solar energy per capita with 85% of households using solar thermal systems (3% of primary national energy consumption), estimated to save the country 2 million barrels (320,000 m 3 ) of oil per year.
In 2005, Spain became the first country in the world to require the installation of photovoltaic power plants in new buildings, and the second (after Israel) to request installation of solar water heating systems, in 2006.
Asia
After 1960, the system is marketed in Japan.
Australia has various national and state and regulations for solar thermal starting with MRET in 1997.
The solar water heater system is popular in China, where the basic model starts around 1,500 yuan (US $ 235), about 80% less than in Western countries for the given collector size. At least 30 million Chinese households have it. Its popularity is due to the efficient evacuated tubes that allow the heater to function even under a gray sky and at temperatures well below freezing.
Latin America
Colombia is developing a local solar water heater industry thanks to the Las Gaviotas design, directed by Paolo Lugari. Driven by a desire to reduce costs in social housing, the team studied the best systems of Israel and made adaptations to meet the specifications set by Banco Central Hipotecario (BCH) which requires systems to operate in cities like overcast BogotÃÆ'¡ for more than 200 days every year. The main design was so successful that Las Gaviotas offered a 25-year warranty on installation in 1984. Over 40,000 were installed and still functioned a quarter of a century later.
Maps Solar water heating
Design requirements
The type, complexity and size of the solar water heating system are largely determined by:
- Changes in ambient temperature and solar radiation between summer and winter
- Changes in ambient temperature during the day-night cycle
- The possibility of drinking or collecting liquids is either too hot or frozen
Minimum system requirements are usually determined by the amount or temperature of hot water required during the winter, when system output and incoming water temperatures are usually at the lowest point. The maximum output of the system is determined by the need to prevent water in the system from overheating.
Freeze protection
The freeze protection action prevents damage to the system due to the expansion of the freezing transfer fluid. The drainage system drains the transfer fluid from the system when the pump stops. Many indirect systems use antifreeze (eg, propylene glycol) in heat transfer fluids.
In some direct systems, collectors can be manually dried when freezing is expected. This approach is common in climates where freezing is not common, but rather unreliable because it depends on the operator.
The third type of freezing protection is a frozen tolerance, in which a low pressure polymer duct made from silicone rubber enlarges during freezing. One such collector now has the European Solar Keymark accreditation.
Overheat protection
When no hot water is used for a day or two, liquids in collectors and storage can reach high temperatures in all non-drainback systems. When the storage tank in the drainback system reaches the desired temperature, the pump stops, terminates the heating process and thereby prevents the storage tank from overheating.
Some active systems deliberately cool water in the storage tank by circulating hot water through collectors when there is little sunlight or at night, heat loss. This is most effective in direct or thermal and almost ineffective store pipes in systems that use evacuated tube collectors, because of their superior insulation. Each type of collector may still be too hot. The high pressure, sealed solar thermal system ultimately depends on the operation of temperature and pressure relief valves. Low pressure, open ventilated heater has simpler and more reliable safety control, usually an open vent.
System
Examples of design include a simple glass insulated box with a flat solar absorber made of metal sheets, attached to a copper and dark-colored heat exchanger, or a set of metal tubes surrounded by an evacuated glass cylinder (near the vacuum). In cases of industrial parabolic mirrors can concentrate sunlight on the tube. Heat is stored in a hot water storage tank. The volume of this tank should be larger with the solar heating system to compensate for bad weather and because the optimal final temperature for solar collectors is lower than typical heating or heating burners. The heat transfer fluid (HTF) for absorbents may be water, but more commonly (at least in active systems) is a separate loop of liquid containing anti-freeze and the corrosion inhibitor provides heat to the tank through a heat exchanger (usually a copper heat exchanger inside the tank). Copper is an important component in solar thermal heating and cooling systems due to its high thermal conductivity, resistance to atmospheric and water corrosion, sealing and merging with soldering and mechanical strength. Copper is used both in receivers and primary circuits (pipes and heat exchangers for water tanks).
Another lower maintenance concept is 'drain-back'. No need to anti-freeze; instead, all the pipes are tilted to cause water to flow back into the tank. The tank is not pressurized and operates at atmospheric pressure. As soon as the pump is off, the flow reverses and the empty pipes before freezing can occur.
Solar thermal solar installation is divided into two groups: passive systems (sometimes called "solid") and active (sometimes called "pumped"). Both usually include an additional energy source (electric heating element or connection to the central heating system of gas or fuel oil) which is activated when the water in the tank falls below the minimum temperature setting, ensuring that hot water is always available. The combination of solar water heating and reserve heat from wood chimneys can allow hot water systems to work year-round in colder climates, without the additional heat requirements of solar water heating systems filled with fossil fuels or electricity.
When the solar water heaters and central heating systems of hot water are used together, the sun's heat will be concentrated in pre-heating tanks inserted into a heated tank by a central heating, or a solar heat exchanger will replace the lower heating element. and the top element will still provide additional heat. However, the main requirement for central heating is at night and in winter when the solar gain is lower. Therefore, solar water heater for washing and bathing is often a better application than central heating because supply and demand are more suitable. In many climates, solar hot water systems can provide up to 85% of domestic hot water energy. This may include a non-electric solar thermal system that concentrates domestic electricity. In many northern European countries, combined heat and water heating systems (solar comb systems) are used to provide 15 to 25% of home heating energy. When combined with storage, large scale solar heaters can provide 50-97% of annual heat consumption for district heating.
Heat transfer
Live
The Direct or open loop system distributes drinking water through the collector. They are relatively inexpensive. Disadvantages include:
- They offer little or no overheating protection unless they have a heat export pump.
- They offer little to no freezing protection, unless the collector is cold-headed.
- Collectors collect scales in hard water areas, except ion exchange softeners are used.
The emergence of a tolerant-freezing design extends the market for SWH to cold climates. In frozen conditions, the previous model was damaged when water turned to ice, broke one or more components.
Indirect
Indirectly or closed loop the system uses a heat exchanger to transfer heat from fluid "fluid heat transfer" (HTF) to drinking water. The most common HTF is an antifreeze/water mixture that typically uses non-toxic propylene glycol. Once heated on the panel, HTF runs into a heat exchanger, where the heat is transferred to the drinking water. The indirect system offers freezing protection and is usually overheated.
Propulsion
Passive
Passive systems rely on hot convection or heat pipe to circulate the working fluid. Passive systems are cheaper and require low maintenance or no maintenance, but are less efficient. Too hot and frozen is the main problem.
Active
Active System uses one or more pumps to circulate water and/or heating liquids . This allows for a wider system configuration.
Pumped systems are more expensive to buy and operate. However, they operate at higher efficiency can be more easily controlled.
Active systems have controllers with features such as interactions with electric water heaters or gas-driven gas, calculation and felling of stored energy, safety functions, remote access and informative display.
Passive direct system
The integrated collector storage system (ICS or batch heater) uses a tank that serves as a storage and collector. Batch heater is a thin rectilinear tank with glass side facing the sun during the day. They are simpler and cheaper than collectors of plates and tubes, but they may require bracing if mounted on the roof (to support 400-700 pounds (180-320 kg) pounds of water), suffered significant heat loss at night from side facing partial sun large uninsulated and suitable only in temperate climates.
The heat storage convection (CHS) system is similar to the ICS system, except physically separate storage and collector tanks and the transfer between the two is driven by convection. CHS systems typically use standard flat-plate or evacuated tube collectors. Storage tanks should be placed on top of the collector for convection to function properly. The main advantage of the CHS system over the ICS system is that heat loss is greatly avoided because the storage tank can be completely isolated. Because the panel is located under the storage tank, heat loss does not cause convection, because cold water remains at the lowest part of the system.
System not directly active
Pressurized antifreeze system uses an antifreeze mixture (almost always non-toxic propylene glycol) and water mixture for HTF to prevent frozen damage.
While effective to prevent frozen damage, antifreeze systems have disadvantages:
- If the HTF gets too hot, the glycol gets degraded to acid and then does not provide freezing protection and begins to dissolve the loop component of the sun.
- A drainback-free system must distribute HTF - regardless of storage tank temperature - to prevent HTF from degrading. Excessive temperatures in the tank lead to increased scale and sediment formation, the possibility of severe burns if the tempering valve is not installed, and if used for storage, the possibility of thermostat failure.
- HTF glycol/water should be replaced every 3-8 years, depending on the temperature experienced.
- Some jurisdictions require more expensive double-wall heat exchangers even though propylene glycol is non-toxic.
- Although HTF contains glycols to prevent freezing, it circulates hot water from storage tanks to collectors at low temperatures (eg below 40Ã, Â ° F (4Ã, Â ° C)), causing massive heat loss.
The drainback system is an indirect active system in which HTF (usually pure water) circulates through the collector, driven by the pump. The collector pipe is not pressurized and includes an open drainback reservoir contained in the conditioned or semi-conditioned chamber. HTF stays in the drainback reseervoir unless the pump operates and returns there (empty the collector) when the pump is turned off. Collector systems, including piping, must flow through gravity to the drainback tank. Drainback system does not freeze or overheat. Pumps only operate when suitable for heat collection, but not to protect HTF, improve efficiency and reduce pumping costs.
Do it yourself (DIY)
Plans for solar water heating systems are available on the Internet. DIY SWH systems are usually cheaper than commercial ones, and they are used both in developed and developing countries.
Comparison
Components
Collector
The solar thermal collector captures and retains heat from the sun and uses it to heat the liquid. Two important physical principles govern solar thermal collector technology:
- Each hot object eventually returns to its thermal equilibrium with its environment, due to heat loss from conduction, convection and radiation. Efficiency (the proportion of heat energy maintained for a predetermined period of time) is directly related to heat loss from the collector surface. Convection and radiation are the most important sources of heat loss. Thermal insulation is used to slow heat loss from hot objects. It follows the Second law of thermodynamics ('equilibrium effect').
- Heat loses faster if the temperature difference between the hot object and its environment is greater. Heat loss is largely governed by a thermal gradient between the collector surface and ambient temperature. Conduction, convection and radiation all occur faster over a large thermal gradient (delta- t effect).
Flat plate
The flat plate collector is an extension of the idea of ​​placing collectors in an 'oven'-like box with glass directly facing the Sun. Most flat plate collectors have two horizontal pipes at the top and bottom, called headers, and many vertical pipes connecting them, called stairs. The rungs are welded (or similarly connected) to a thin absorbent fin. Liquid heat transfer (water or water/antifreeze mixture) is pumped from a hot water storage tank or heat exchanger to the collector's lower header, and travels upwards, collects heat from the absorber fins, and then exits the collector out of the top canopy. The Serpentine flat plate collector is slightly different from the "harp" design, and instead uses a single pipe that goes up and down the collector. However, since they can not be drained properly water, serpentine plate collectors can not be used in drainback systems.
The type of glass used in flat plate collectors is almost always low in iron, tempered glass. Such glasses can withstand significant hailstones without breakage, which is one reason flat plate collectors are considered the most durable collector types.
Collectors that are not shiny or formed are similar to flat plate collectors, unless they are not thermally insulated or physically protected by a glass panel. As a result, this type of collector is much less efficient. For pool heating applications, the water to be heated is often colder than the ambient roof temperature, where the point of lack of thermal insulation allows additional heat to be extracted from the surrounding environment.
Evacuated tube
The evacuated tube collector (ETC) is a way to reduce heat loss, which is attached to a flat plate. Because heat loss due to convection can not pass through a vacuum, it forms an efficient isolation mechanism to keep heat inside the collector pipe. Since two flat glass sheets are generally not strong enough to withstand a vacuum, a vacuum is made between two concentric tubes. Typically, the water pipes in the ETC are therefore surrounded by two concentrator-separated glass tubes that recognize the heat from the sun (for heating pipes) but that limit heat loss. The inner tube is coated with a heat absorber. Vacuum life varies from collector to collector, from 5 years to 15 years.
Flat plate collectors are generally more efficient than ETCs in full sunlight conditions. However, the energy output of the flat plate collector is reduced slightly more than the ETC in cloudy or very cold conditions. Most ETCs are made of annealed glass, susceptible to hail, failing to roughly measure golf-sized particles. ETC made of "coke glass", which has a green color, is stronger and less likely to lose its vacuum, but its efficiency is slightly reduced due to reduced transparency. ETCs can collect energy from the sun all day long at low angles because of their tubular shape.
Pump
PV Pump
One way to turn on the active system is through a photovoltaic panel (PV). To ensure proper pump performance and long life, the pump (DC) and PV panel should be suitable. Although a PV-powered pump does not operate at night, the controller must ensure that the pump is not operating when the sun is out but the collecting water is not hot enough.
The PV pump offers the following advantages:
- Simplified/cheaper install and maintenance
- Excess PV output can be used for household electrical usage or put back into the grid.
- Can reduce the humidity of living space.
- Can operate during power outages.
- Avoid carbon consumption from the use of grid-powered pumps.
Bubble Pump
A bubble pump (also known as a geyser pump) is suitable for flat panels as well as vacuum tube systems. In the bubble pump system, the closed HTF circuit is under reduced pressure, which causes the liquid to boil at low temperatures as the sun heats it up. The bubbles form a geyser, causing upward flow. The bubbles are separated from hot liquids and condense at the highest point in the circuit, after which the liquid flows downward to the heat exchanger caused by the difference in the liquid level. HTF usually arrives at a heat exchanger at 70 ° C and returns to the circulating pump at 50 ° C. Pumping usually begins at about 50 ° C and increases as the sun rises until equilibrium is reached.
Controller
A differential controller senses the temperature difference between the water leaving the solar collector and the water in the storage tank near the heat exchanger. The controller starts the pump when the water in the collector is about 8-10 ° C warmer than the water in the tank, and stops when the temperature difference reaches 3-5 Â ° C. This ensures that the stored water always gets hot when the pump operates and prevents the pump from excessive and deadly cycling. (In direct systems the pumps can be triggered with a difference of about 4 Â ° C because they do not have heat exchangers.)
Tank
The simplest collector is a water tank filled with water in a sunny place. The sun heats the tank. This is how the first system works. This arrangement will be inefficient because of the equilibrium effect: as soon as the tank heater and water heating begins, the heat obtained is lost to the environment and this continues until the water in the tank reaches ambient temperature. The challenge is to limit heat loss.
- Storage tanks can be placed lower than collectors, allowing increased freedom in system design and allowing existing storage tanks to be used.
- Storage tanks can be hidden from view.
- Storage tanks can be placed in conditioned or semi-conditioned spaces, reducing heat loss.
- Drainback tanks can be used.
Insulated tank
ICS or batch collectors reduce heat loss by thermally isolating the tank. This is achieved by wrapping the tank in a glass box that allows heat from the sun to reach the water tank. Other walls of the box are thermally insulated, reducing convection and radiation. The box can also have a reflective surface on the inside. This reflects the heat lost from the tank back to the tank. In a simple way, one can consider an ICS solar water heater as a water tank that has been enclosed in a type of 'oven' that retains heat from the sun as well as hot water in the tank. Using a box does not eliminate the heat loss from the tank into the environment, but it mostly reduces this loss.
The standard ICS collector has a very limiting characteristic of the collector's efficiency: the surface to volume ratio is small. Since the amount of heat that can be absorbed by a tank from the sun depends heavily on the surface of the tank that is directly exposed to sunlight, the surface size determines the extent to which water can be heated by the sun. Cylindrical objects such as tanks in ICS collectors have a small surface to volume ratio. Collectors are trying to increase this ratio for efficient water heating. Variations in this basic design include collectors incorporating smaller water containers and evacuated glass tube technology, a type of ICS system known as the Evacuated Tube Collector (ETB) collector.
Apps
Evacuated tube
ETSCs can be more useful than other solar collectors during the winter. ETCs can be used for industrial heating and cooling purposes such as pharmaceuticals and pharmaceuticals, paper, leather and textiles as well as for homes, hospitals, nursing homes, hotel swimming pools etc.
ETCs can operate at various temperatures from medium to high for solar hot water, swimming pools, air conditioning and solar cookers.
Higher temperature ETCs (up to 200 Â ° C (392 Â ° F)) make them suitable for industrial applications such as steam generators, heat engines and solar drying.
Swimming pool
The floating pool system and separate STC are used for swimming pool heating.
Pool cover systems, both solid and floating disks, serve as an insulator and reduce heat loss. Much of the heat loss takes place through evaporation, and using the cover slows down the evaporation.
STC for noncompact pool water use is often made of plastic. The pool water is slightly corrosive due to the chlorine. Water is circulated through a panel using an existing pool filter or an additional pump. In a lightweight environment, the glazeless plastic collector is more efficient as a direct system. In cold or windy environments, evacuated tubes or flat plates in an indirect configuration are used in conjunction with heat exchangers. It reduces corrosion. Simple, simple temperature controllers are used to direct water to a panel or heat exchanger either by turning the valve or operating the pump. Once the pond water reaches the required temperature, the flow valve is used to return water directly to the pond without heating. Many systems are configured as drainback systems where water flows into the pool when the water pump is turned off.
Collector panels are usually installed on the nearest roof, or mounted on the ground on a sloped shelf. Due to the low temperature difference between air and water, the panel is often formed collector or collector flat plate without glaze. A simple rule of thumb for the required panel area is 50% of the pool surface area. This is for the area where the pool is used in summer only. Adding a solar collector to a conventional outdoor swimming pool, in cold climates, can usually extend the use of a comfortable swimming pool for months and more if the insulated pool cover is used. An active solar energy system analysis program can be used to optimize the solar pond heating system before it is built.
Energy production
The amount of heat sent by the solar water heating system depends primarily on the amount of heat delivered by the sun in a particular place (insolation). In the tropics, insolations can be relatively high, eg. 7 kWh/m2 per day, compared for example, 3.2 kWh/m2 per day in temperate climates. Even at the same insolation the same latitude can vary greatly from location to location due to differences in local weather patterns and cloudy numbers. A calculator is available for estimating insolation on a site.
Below is a table which gives a rough indication of the specification and energy that can be expected from a solar water heating system involving about 2 m 2 of the collector absorber region, showing two evacuated tubes and three flat plate heating systems the sun. Certification information or figures calculated from the data are used. The bottom two lines provide estimates for daily energy production (kWh/day) for the tropical and moderate scenarios. This estimate is to heat water up to 50Ã, Â ° C above room temperature.
With most of the solar water heating systems, the energy output scale is linear with the surface area of ​​the collector.
These figures are quite similar among the above collectors, yielding about 4 kWh/day in temperate climates and about 8 kWh/day in tropical climates when using collectors with a 2 m 2 buffer. In this scenario the temperature is sufficient to heat 200 liters of water about 17 ° C. In the same tropical heating scenario will occur around 33 Â ° C. Many thermosiphone systems have energy outputs comparable to equivalent active systems. The efficiency of the evacuated tube collector is somewhat lower than that of the flat plate collector because the narrower absorber of the tube and tube has the space between them, resulting in a significantly greater percentage of the inactive collector area. Some comparative methods calculate the efficiency of tube collectors evacuated based on the actual absorbing region and not on the occupied space as has been done in the above table. Efficiency is reduced at higher temperatures.
Cost
In a sunny and warm location, where freezing protection is not required, batch type solar heaters can be cost-effective. At higher latitudes, design requirements for cold weather add to the complexity and cost of the system. This increases initial costs, but not the lifecycle cost. Therefore, the single biggest consideration is the large initial financial outlay of solar water heating systems. Keeping up with these costs can take years. Longer repayment period in moderate climates. Due to the free solar energy, the operational costs are small. At higher latitudes, solar heating may be less effective because of lower insulation, may require larger and/or double heating systems. In some countries, government incentives can be significant.
Cost factors (positive and negative) include:
- The price of solar water heaters (more complex systems are more expensive)
- Efficiency
- Installation costs
- Electric used for pumping
- The price of fuel water heater (eg gas or electricity) is stored per kWh
- The amount of water heater used
- Initial subsidies and/or government subsidies
- Maintenance costs (eg antifreeze or pump replacement)
- Savings in the maintenance of conventional water heating systems (electricity/gas/oil)
The timing of returns can vary greatly because of the regional sun, additional costs due to the protection of frost need of collectors, the use of household hot water, etc. For example in central Florida and south payback periods could easily be 7 years or less than the 12.6 years indicated on the chart for the US
Shorter payback times are given greater insolation. However, even in temperate regions, solar water heaters are cost effective. Period of return for photovoltaic systems has historically been much longer. The cost and payback times are shorter if no supplementary/backup system is needed. thus extending the return period of such a system.
Subsidents
Australia operates the Renewable Energy Credit system, based on national renewable energy targets.
The Toronto Solar Neighborhood Initiative offers subsidies for purchasing solar water heating units.
Energy footprint and lifecycle rating
Energy footprint
The power source in the active SWH system determines the extent to which the system contributes to atmospheric carbon during operation. Active solar thermal systems that use primary electricity to pump liquids through a panel are called 'low carbon diesel'. In most systems, pumping reduces energy savings by about 8% and carbon savings from the sun by about 20%. However, low power pumps operate with 1-20W. Assuming the solar collector panel sends 4 kWh/day and the pump that runs intermittently from the main power for a total of 6 hours for 12 hours a day is bright, the negative effects of the pump can be reduced to about 3% of the heat. produced.
However, active solar PV-powered heat systems typically use 5-30 W PV panels and low-power diaphragm pumps or small centrifugal pumps to drain water. This reduces carbon footprint and operational energy.
Alternative non-electric pumping systems can use thermal expansion and fluid and gas phase changes.
Life cycle energy savings
Approved standards can be used to provide robust and quantitative life-cycle assessments (LCAs). LCA considers the financial and environmental costs of acquiring raw materials, manufacturing, transportation, use, service, and disposal of equipment. Elements include:
- Financial costs and benefits
- Energy consumption
- CO 2 and other emissions
In terms of energy consumption, about 60% goes into the tank, with 30% toward the collector (flat plate of thermosiphon in this case). In Italy, about 11 giga-joules of electricity are used in producing SWH equipment, with about 35% going to the tank, with another 35% going to collectors. The main impact associated with energy is emissions. The energy used in manufacturing recovers within the first 2-3 years of use (in southern Europe).
In contrast the time of return of energy in the UK reported only 2 years. This figure is for direct systems, installed into existing water stores, pumped PV, frozen tolerance and aperture of 2.8 square meters. For comparison, the PV installation takes about 5 years to achieve energy returns, according to the same comparative study.
In terms of CO 2 emissions, most of the emissions stored depend on the extent to which gas or electricity is used to supplement the sun. Using the 99-point Eco-indicator system as a benchmark (ie the annual environmental load of the average European population) in Greece, gas-driven pure systems may have fewer emissions than the solar system. This calculation assumes that the solar system produces about half of the household's hot water needs.
The test system in Italy produces about 700 kg of CO 2 , considering all components of manufacture, use, and disposal. Maintenance is identified as a cost-emission activity when the heat transfer fluid (based on glycols) is replaced. However, emission costs are recovered within about two years of equipment use.
In Australia, life cycle emissions are also found. The SWH system tested has about 20% the impact of an electric water heater and half of the gas water heater.
Analyzing their low impact retrofit freeze-tolerant solar water heating system, Allen et al. (qv) reported the production of CO 2 impacts of 337 kg, of which about half of the impact environment was reported in the Ardente study et al. (qv).
System specifications and installation
- Most SWH installations require backup heating.
- The amount of hot water consumed daily should be replaced and heated. In a sun-only system, consuming a high water fraction in the reservoir implies a significant variation in reservoir temperature. The larger the reservoir the smaller the daily temperature variations.
- The SWH system offers significant economies of scale in the cost of collectors and tanks. Thus the most economically efficient scale meets 100% of the demand for heating applications.
- The direct system (and some systems do not directly use heat exchangers) can be installed into an existing store.
- Equipment components must be isolated to achieve full system benefits. Efficient insulation installation significantly reduces heat loss.
- The most efficient PV pumps start slowly in low light levels, so they can cause a small amount of unwanted circulation while the collector cools down. The controller shall prevent stored hot water from this cooling effect.
- The evacuated tube collector array can be adjusted by removing/adding tubes or heat pipe, allowing adjustment during/after installation.
- Above 45 degrees latitude, the collector facing the roof tends to produce collectors mounted on the wall. However, a steep collector arrangement mounted on the wall can sometimes produce more useful energy because the increased energy used in winter can offset the loss of unused energy (excess) in the summer.
Standard
Europe
- EN 806: Specifications for in-building installations that carry water for human consumption. General.
- EN 1717: Protection against drinking water contamination in water installations and general device replacement to prevent pollution by backflow.
- EN 60335: Specifications for the safety of household electrical appliances and the like. (2-21)
- UNE 94002: 2005 Thermal solar system for domestic hot water production. Method of calculation for heat demand.
United States
- OG-300: OG-300 Certification of Solar Water Heater System.
Canada
- CAN/CSA-F378 Series 11 (Solar Collector)
- CAN/CSA-F379 Series 09 (Solar domestic hot water system packed)
- SRCC Standard 600 (Minimum standard for solar thermal collector)
Australia
- Renewable Energy (Electricity) Act 2000
- Renewable Energy (Electricity) (Cost Disadvantages of Large-Scale Generation) Acts 2000
- The Small-scale Technology Shortfall Charge Act 2010
- Renewable Energy (Electrical) Regulations 2001
- Renewable Energy Regulations (Electricity) 2001 - STC Calculation Methodology for Solar Water Heaters and Heat Pumps Air Source Pump
- Renewable Energy (Electricity) Amendments (Transitional Provisions) Regulations 2010
- The Renewable Energy (Electrical) Regulations Amendments (Transitional Provisions) 2009
All relevant participants of the Large Scale Renewable Energy Targets and Small Scale Renewable Energy Schemes must comply with the Acts above.
Worldwide use
Europe
See also
- Concentrate on solar power
- Passive Sun
- Commercialization of renewable energy
- Heat that can be updated
- Solar air conditioning
- Solar air heater
- The solar system
- Solar energy
- Solar hot water in Australia
- Solar thermal collector
- Solar thermal energy
- Continuous design
References
External links
- Part of the solar heating system
Source of the article : Wikipedia
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