Solar water heaters

Many further solar energy developments and demonstrations took place m the first half of the twentieth century. However, only one solar technology survived the commercial competition with cheap fossil fuels. That exception was solar water heaters that were widely used in Japan, Israel, Australia and Florida, where electricity was expensive and before low-cost natural gas became available. 

Use of solar panels or photovoltaics (PVs) is another popular way to generate solar electricity. The space program is perhaps the most recognized user of PVs and is responsible for most of the advancements in PVs. Many people are familiar with PVs through small applications such as calculators and perhaps solar water heaters, but early forays in PV experimentation were little more than noted side observations in non-PV experiments. 

Hoftman, J. S. Well, J. B. and Guiney, W. T. (1998). Transforming the Market for Solar Water Heaters A New Model to Build a Permanent Sales Force. Renewnble Energy- Policy Project No. 4. . 

Early in the twentieth centui y over 150 different manufacturers were making storage tank, instantaneous, and solar water heaters. Then as indoor plumbing became more common and as people started using showers more and baths less, storage type water heaters became more popular. Accurate hot water temperatures were not possible in early instantaneous water heaters. This was not much of a prob-... 

In 1909 one company began selling solar water heaters with separate collectors and insulated storage tanks. The collectors were made of copper tubing soldered to a copper plate in a glass covered box. The hot water was transferred to the storage tank by thermosyphon action, so the insulated tank had to be installed above the collector, typically in the attic or on the roof It was often connected to an auxiliary heater on the stove or furnace to supplement solar... 

Solar water heating declined in Southern California in the 1920s due to the development of natural gas, but it continued in Florida where natural gas was very expensive. In 1941 more than half Miami s population had solar water heaters, and more than 80 percent of new homes built then were equipped with solar water heaters. By the end of the 1950s in Florida, solar water heating was displaced by electricity as the price dropped and the storage tanks of solar water heaters failed because of galvanic corrosion from connecting steel tanks to copper collectors. 

Tax credits were provided for solar water heating systems in response to the energy crisis. After tax credits expired, the solar water heater business declined drastically. The only segment of solar water heater market that has continued to have growth is the pool heater. 

Solar water heaters (SWHs) are relatively expensive to install ( 500— 2100), although the initial investment can be recovered through future electricity savings [1], For many families in rural areas, the purchase of a solar lighting set, even for lighting service only, is so hard that a... 

Passive Solar A system in which solar energy (heat from sunlight) alone is used for the transfer of thermal energy. Heat transfer devices that depend on energy other than solar are not used. A good example is a passive solar water heater on the roof of a building. 

The technology is scalable in that it can be used for domestic heating purposes or on a larger scale for commercial electricity generation, as solar water heaters are an established technology, widely available and simple to install and maintain. 

By the late 1800s, the use of solar water heaters was common in sunny parts of the United States. When large deposits of oil and natural gas were discovered, these systems were replaced with heaters using cheaper fossil fuels. 

Open-Loop System - A heating system, such as a solar water heater or geothermal heatpump, in which the working fluid is heated and used directly In an open-loop solar system, the domestic water is circulated in the collector loop. 

The absorber may be a solid (e.g., concrete) wall with a black coating. In the case of solar dryers, this solution is justified if the wall is the dryer housing wall. Its operating principle is the same as that of the Trombe wall used in passive solar heating [56]. (For collector-integrated solar water heaters, see Refs. [105,108].)... 

Active Solar Heating. Solar thermal technologies can be used for water heating, space heating, air-conditioning, and process heating. The most common types of solar water heaters are glazed flat-plate... 

K. Sopian, M. Syahri, S. Abdullah, M.Y Othman and B. Yatim. Performance of non metallic unglazed solar water heater with integrated storage system. Renewable Energy 2004 29 1421-1430. 

Repeating cycles of loading and unloading are quite important for TES PCM based. The operation of the system can interrupt, in the case where the discharged PCM could not be charged. This is likely to occur for the PCM-based TES working on natural resources, such as solar water heater, solar space heater, etc. 

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