Solar water heating systems almost always require some kind of thermal storage for solar heated water. Tanks used in solar water heating systems are available in two basic types: pressurized and atmospheric.

Pressurized tanks, constructed of stainless steel or welded steel with a baked-on glass liner, are made to withstand city water pressure without rupturing. Polyurethane foam insulation is used in between the metal skin and interior tank to minimize heat loss. Pressure relief valves are included in the design of pressurized tanks. If the pressure builds up too high inside the tank, the relief valve opens and water is released. Pressurized tanks range from about $500 for an 80 gallon capacity to about $17,000 for a 1,000 gallon capacity. The life span of a pressurized tank around 13 years but can vary depending on local water conditions and tank maintenance (changing the anode rods regularly).

Atmospheric tanks are basically just non-pressurized containers to hold solar heated water. Since they are not completely sealed from the surrounding atmosphere, they should be well insulated. An atmospheric tank that is filled beyond its capacity will overflow. In addition, atmospheric tanks will lose water through evaporation. A variety of materials are used in the construction of atmospheric and include stainless steel, EPDM lined steel, EPDM lined wood, polypropylene and fiberglass. Tank costs and longevity vary with material selection.

A two tank solar water heating system consists of a solar storage tank (it can be atmospheric or pressurized) and a pressurized backup tank. A one tank solar water heating system uses a pressurized tank which serves both as the solar storage tank and the backup water heater.

Simply stated, when using an atmospheric solar storage tank in your design, heat from the collectors is delivered first to the atmospheric tank, then on to the pressurized tank. When no atmospheric tank is used in the
design, with only a pressurized tank, the solar heat can be sent directly to the one pressurized tank.

Should you incorporate an atmospheric solar storage tank in your solar thermal design? Your solar equipment manufacturer should be able to help you decide what is best for your individual needs. However, if your tank capacity needs to be over 240 gallons, it may make sense to include an atmospheric tank for economic reasons.

See upcoming blog article for more information regarding atmospheric tanks.

G. Paul Menyharth, director of the American Solar Institute, weighs in with the test data and collector performance concluding that “the selection should be based on how much energy could be collected per dollar spent for the desired application.”

LEED Version 3 (Leadership in Energy and Environmental Design) is a worldwide accepted certification system for the design, construction and operation of green buildings. Developed by USGBC (United States Green Building Council), LEED Version 3 supports and encourages whole-building design approaches.

LEED Version 3 certification uses a point scoring system where points are given for building projects that strive for energy savings, water efficiency, carbon emission reduction, enhanced indoor environmental quality, and management of resources. A total of 110 points are offered, including 10 bonus points. A minimum number of 40 points is needed for a building project to become certified. The four levels of LEED Version 3 certification and their required points are: Platinum, 80-110; Gold, 60-79; Silver, 50-59; Certified, 40-49.

LEED Version 3 points are available in the following categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, Innovation in Design and Regional Priority.

The Energy and Atmosphere category offers a total of 35 possible points. This category is further broken down into six specific credits. Credit 1 is named Optimize Energy Performance. A total of nineteen points may be given for Credit 1. Credit 2 is called On-Site Renewable Energy, which offers a total of seven points.

If your building project is incorporating a solar thermal system, you may be able to receive LEED Version 3 points from Credit 1, Optimize Energy Performance. (Since solar thermal does not actually generate power like solar electric does, the energy savings received from solar thermal does not qualify in Credit 2, On-Site Renewable Energy.)

LEED Version 3 points from Credit 1 for inclusion of a solar thermal system are calculated by first establishing a reference building as a baseline. Then data regarding the system is analyzed using a simulation software program, comparing it to the baseline. One point is awarded for every 3.5% of energy efficiency over the baseline, with a maximum of ten points available.

Since solar thermal is generally less expensive than many other renewable energy technologies, it is a much more economically feasible way of obtaining LEED Version 3 points for your building project.

While solar site evaluation tools determine the best location for the solar collectors used in a solar heating or photovoltaic installation, solar simulation software provides the software tools to help design and simulate a solar energy installation and facilitates the design making process.

Three leading companies that offer solar simulation software packages to those in the renewable energy fields are RETScreen International, Vela Solaris AG and Valentin Energy Software.

At the onset of a new renewable energy project, each one of the three companies’ software package allows the user to input information regarding the site’s location and define the energy requirements for the project. The user may then select a template or configuration from the software’s database, and in addition, may select specific commercially available products to be used. The software will generate the simulation evaluation which will include financial feasibility and potential cost savings, calculation of weather data, energy production, expected energy savings and emission reductions of the project.

RETScreen International developed their Clean Energy Project Analysis Software with the input of experts from government, industry and academia from around the world. RETscreen is applicable to various categories of renewable energy, not just solar energy. The software consists of a series of worksheets to be filled in by the user, along with a comprehensive database that is the largest and most detailed of the three software packages. The user may omit any of the worksheets that do not apply to their project. It is suitable for large commercial and governmental projects, although it may also be used with smaller residential undertakings. RETscreen software may be downloaded free from their website.

Polysun Simulation Software was developed by Vela Solaris AG, a Swiss corporation. Polysun Simulation Software is a set of four software programs specifically created for the design of heat pumps, solar thermal, photovoltaic and cooling systems. Each software program is available separately or as a complete set of four. In addition, each program is offered in three user levels, light, professional and designer. The evaluation process provides detailed reports in PDF format, including colorful graphics, and is a significant feature of this software. A Polysun demo copy may be downloaded for examination on the Vela Solaris AG website. Polysun is also available for purchase on the site.

Valentin Energy Software, based in Berlin, Germany, offers two solar energy simulation programs. Their T’SOL software was conceived for solar thermal energy systems, while their PV’SOL is for used in the design of solar photovoltaic systems. Both programs are also available in three user levels, express, professional and expert. The company’s Meteonorm software, a global climate data database, is also available separately. Customized versions of T’SOL and PV’SOL may also be developed by Valentin for individual user objectives. Valentin Energy Software may be purchased through distributors or online on the company website.

What one of these is the best solar simulation software package? Our suggestion is to download the free copy of RETscreen and try it out. If RETscreen does not meet the needs of your applications, then download the demo copy of Polysun and determine if this software is a better choice for your company. In our evaluation of the T*Sol product we found that it didn’t compete effectively with the Polysun for a number of reasons. Most notably was the lack of SRCC certified collectors and standard U.S. components. If RETscreen or Polysun does not provide the requirements that you need, perhaps your company should consider a customized version of Polysun, T’SOL or PV’SOL.

Although the main objective of each of these software packages is to facilitate in the design process, the professional looking reports generated by them will also assist solar energy companies in the marketing of their products to potential customers.

The U.S. solar water heating industry produced a record year of growth in 2008, with a 50% increase in capacity compared to 2007. By the end of 2008, approximately 139 MWTh (MegaWatts Thermal equivalent) was installed, bringing the total installed capacity to about 485 MWTh, according to a report released by the Solar Energy Industries Association.

One of the main reasons for the growth of the solar water heating industry was the extension of the residential and commercial solar investment tax credit. Additionally, the public has become increasingly aware of solar energy options available and more concerned about the overall energy crisis.

Even with the significant growth of the solar water heating industry in 2008, solar energy (solar water heating and photovoltaics combined) accounts for only 1% of the total U.S. energy usage. This small percentage is mainly concentrated in several states, possibly as a result of varying http://www.solarhotusa.com/support.html. The state of Hawaii, with its tax credit of 35% of the cost of a solar hot water installation, accounted for 37% of the total MWTh installed in the U.S. in 2008.

The U.S. currently ranks fourth in the world in installed solar energy capacity (solar water heating and photovoltaics combined). Germany ranks first, with Spain and Japan ranking second and third respectfully.

It is expected that the U.S. solar water heating industry will continue to grow in the coming years as the country confronts the issue of reducing solar energy costs to the same level as that of conventional fossil fuel energy.

Legionnaires’ disease is a form of pneumonia caused by the bacterium Legionella Pneumophila. Individuals are infected by inhalation of sprays, mists or microscopic droplets of water contaminated with the bacterium. Although Legionella Pneumophila is naturally occurring at low levels in bodies of water, it is not likely that an individual would develop Legionnaires’ disease from these sources.

What does Legionnaires’ disease and Legionella Pneumophila have to do with solar hot water heating systems?

Legionella Pneumophila may live and possibly flourish in almost any water system or equipment that distributes water as a spray or mist, including residential and commercial solar hot water heating systems. Can you be infected by the bacterium by taking a shower in your own home? Yes, it is possible, but unlikely.

Legionella Pneumophila is much more likely to be found in substantial levels in the larger water systems of workplaces and public facilities such as, but not limited to, hotels, cruise ships and hospitals. In addition to conventional and solar hot water heating systems, the bacterium may also exist in the cooling towers of industrial cooling water systems, large central air conditioning systems, evaporative coolers, whirlpool spas, ice making machines and decorative fountains.

Water systems with warm stagnant water provide the best environment for the growth of Legionella Pneumophila. The bacterium can begin to multiply at temperatures between 68°F and 122°F, with the most favorable temperature range being between 90°F and 105°F. The incidence of rust and other microorganisms can also promote increased growth. Dead legs in the water system design may provide a favorable place for the bacterium to grow.

When water temperature is increased to 131°F, Legionella Pneumophila will be destroyed in several hours. At temperatures above 158°F, the bacterium is immediately destroyed.

To prevent the growth of Legionella Pneumophila, it is recommended that solar hot water heating systems be operated at 140°F. In public water systems biocides such as chlorine are also used to eliminate the bacterium, as well as ultraviolet-C light in conjunction with specialized ultrasonic processes.

Those installing or repairing solar hot water systems should take into consideration the environmental conditions that promote the growth of Legionella and shoot to avoid those situations by cleaning all piping, fittings and other equipment before assembly. Since many solar systems operate with the solar tank pre-heating the water going into a back-up heater that is set high enough to destroy the bacteria it should not be a concern.

Everyone that has looked into the details is impressed with the relative economic value of a solar water heating system compared with any other renewable energy source. Even if a potential customer is impressed with the economics of solar heating it doesn’t mean that they can necessarily pay for it. Many potential customers don’t have access to the cash so discussions of tax incentives and rebates fall on deaf ears if they don’t have the money up front.

One of the missing pieces in the solar heating equation has been the financing. This has been a hurdle at both the residential and commercial level. I am aware of a number of banks that offer different systems but one that came to mind recently that I thought had some merit was www.sameascashloans.com . The premise is that you can offer your customers a solar system and they can defer the first payment for anywhere between 3, 6, 12, or 18 months. This way the customer doesn’t have to be cash out of pocket until they are realizing the tax savings.

On the commercial side it is a little more like standard financing but the availability of financing makes this a strong option for growing your solar heating business.

With the cost of conventional energy ever increasing, consumers are becoming more interested in the use of solar energy. But which solar energy technology makes the most sense for the average consumer, solar heating or solar electric?

A solar heating system generally consists of solar collectors, a water storage tank, a pump and automatic controls. The estimated cost of a hot water solar heating system for a typical single family home is between $4,000 and $8,000, including installation. The system will replace approximately 80% of the energy used by a conventional hot water system, and represents a cost savings of $500 to $600 a year. The payback will average between 5 to 7 years after tax credits, meaning that after 5 to 7 years the total cost savings will have paid for the initial cash investment.

The components of a solar electric system are the photovoltaic solar collectors, an inverter, a charge controller and batteries. The projected cost of a grid-tied solar electric system for the same typical single family home is from $25,000 to $35,000 and will supply approximately 20-25% of the electricity usage of the home. The yearly savings would be between $500 and $600. The payback of the system is estimated at 15 to 25 years.

The initial costs of both of the solar hot water heating system and the solar electric system may be reduced by federal tax credits and state tax incentives. The cost savings per year and payback time for both systems will vary depending on the exact costs of the system components, actual current energy costs and future increases in energy costs.

Neither system is 100% efficient, since energy is lost due to conversion processes. Solar hot water heating systems are considered to be between 35% and 50% efficient, compared to solar electric systems which are 4% to 13% efficient.

In our opinion, because of the lesser initial expenditure, the quicker return of the investment and the higher rate of efficiency, the solar hot water heating system is the better, more cost effective choice.

The European Member States have to work out a Renewables Action Plan this year, outlining how it will reach its 2020 target
by Werner Weiss and Peter Biermayr
London, UK [RenewableEnergyWorld.com]

The European Union and its Member States have committed themselves to achieving a 20% share of renewable energy in Europe’s final energy consumption by 2020. As only three renewable sources (biomass, geothermal and solar) generate heat, it is crucial to clarify how these different sectors can contribute to the renewable energy target. A new study being released this autumn – Study of the Potential of Solar Thermal in Europe, which has come from two Austrian bodies (AEE – Institute for Sustainable Technologies and Vienna University of Technology) examines the growth that can come from solar.

Obviously, solar thermal systems will be needed to provide a substantial share of the low temperature heat: deep geothermal sources are limited to a few locations in Europe, and shallow geothermal is considered within this study as an energy efficiency technology; biomass will be used for transport fuels, electricity generation and medium-to-high temperature applications.

In order to provide the European Union and its Member States with substantiated information on the solar thermal contribution to the 20% renewable energy target and its long-term potential, detailed surveys were conducted using a representative sample of five European countries – Austria, Denmark Germany, Poland and Spain. The information gathered was then extrapolated to cover the 27 EU countries. The study examined both the technical and economic potential of solar thermal technologies, for different applications, including low-temperature industrial heat requirements and cooling.

In order to determine the potential contribution solar thermal could make to the overall heat demand in the selected reference countries, a model was developed for the future demand – taking into account energy efficiency measures. Using this model as a base, future heating and cooling demand was calculated for 2020, for 2030 and 2050. The model includes three scenarios and focuses on the following segments:
* space heating of residential buildings
* hot water preparation in the residential sector
* space heating in the service sector
* industrial low temperature heat (up to 250°C)
* air conditioning and cooling in the residential and service sectors

The three scenarios are a ‘Business As Usual scenario’ (BAU); an ‘Advanced Market Deployment scenario’ (AMD), which includes financial and political support mechanisms such as subsidies and obligations, moderate energy efficiency measures and improved research activities; and a ‘Full R&D and Policy scenario’ (RDP), which includes substantial financial and political support mechanisms, energy efficiency measures and research activities.

Contribution of Solar Thermal to the EU 20% Renewable Energy target

Assuming there is a 9% reduction of the overall final energy demand due to energy efficiency measures by 2020 (compared with 2006), then solar thermal would make up 6.3% of the European Union’s 20% renewable energy target under the RDP scenario, and 2.4% under the less ambitious AMD scenario. The share of renewables in 2005 (to the EU-27’s total energy consumption of 13,609 TWh) was 8.5%. To reach 20%, an increase of 11.5 percentage points in renewable energies is required across the EU-27 countries by 2020. The contribution of solar thermal to that increase would be 12% according to the RDP scenario, 4.5% according to the AMD scenario and 2.9% in the BAU scenario.

To reach the goals of the RDP scenario, a 26% average annual growth rate of the European solar thermal market is needed up to 2020. (By comparison, the average annual market growth in Europe between 2000 and 2007 was 12.4%.) A 15% average annual growth rate is required to reach the goals of the AMD scenario and a 7% growth rate for the BAU scenario. The resulting total collector area by 2020 would be between 97 million m2 (BAU) and 388 million m2 (RDP). These collector areas correspond to total installed capacities of 67.9 GWth and 271.6 GWth, respectively.

Economic Effects

According to the RDP scenario the effect on employment would be considerable. In total, the solar thermal sector would encompass 470,000 full-time jobs in 2020, in the European Union domestic market alone. €214 billion would be required in the solar thermal sector to reach the 2020 goals of the RDP scenario. This includes production, engineering, trade and installation of solar thermal systems from 2006 to 2020.

Solar thermal contribution to the energy supply and CO2 reduction

The solar yield in the RDP scenario is 155 TWh in 2020. This corresponds to an oil equivalent of 22 billion metric tons. Taking this oil equivalent into account the annual contribution to the CO2 reduction by solar thermal systems is 69 million metric tons.

Technology Innovation

Stepping up solar on this scale will require innovation. In order to use the potential much larger roof and facade areas will be needed for the installation of solar collectors.

Large-scale solar renovation of buildings will make use of prefabricated elements, with solar providing space heating, cooling and hot water. Combisystems will play an essential part, and a key issue is the development of thermal energy storage.

Long-Term Potential – Beyond Domestic Hot Water

In 2050, the solar thermal contribution to the European Union’s (EU-27) low temperature heat demand ranges from 47% (RDP scenario) to 8% (BAU scenario).
The corresponding annual solar yields are 1552 TWh (RDP) and 391 TWh (BAU). The collector area needed to reach these goals is between 8 m2 (RDP) and 2 m2 (BAU) per inhabitant in the EU-27. The resulting total collector area is between 3.88 billion m2 (RDP) and 970 million m2 (BAU).

If solar thermal is to contribute significantly to the long-term heating and cooling demand in EU-27 countries then the primary focus in central and northern Europe must be on systems for space heating (solar combisystems) and in the Mediterranean area on systems providing space heating, hot water and air conditioning (solar combi+ systems).

If the focus remains solely on solar thermal systems for domestic hot water preparation, then the solar thermal contribution to the long-term final energy demand will be limited. By 2030 the full potential for these applications will have been reached and the market would be reduced mainly to the replacement of old systems. Another important segment with considerable potential is low-temperature process heat for industry, (up to 250°C).

With upscaled R&D and market/political support, solar heat can make a valuable contribution to Europe’s energy future. It’s the right moment – in fact, without the renewable heat sector, the 2020 targets will not be reached.

Werner Weiss is at AEE – Institute for Sustainable Technologies, Gleisdorf, Austria. Peter Biermayr is with Vienna University of Technology Energy Economics Group, Austria.

The full version of the Solar Thermal Potential in Europe study is available: http://www.estif.org/.

This study was prepared in the framework of the EU-funded project RESTMAC, TREN/05/FP6EN/S07.58365/020185. The Solar Thermal partner in the RESTMAC project is ESTIF, European Solar Thermal Industry Federation.

Solar heating system gets prominent display during the 2009 solar tour.

http://wake.mync.com/site/Wake/news/story/42654/solar-powered-homes-businesses-go-on-display/