Polypropylene atmospheric solar storage tanks have the longest lifespan, at about 50 years. Polypropylene is a rigid plastic that is rotationally molded. Tanks are constructed of Polypropylene but would need to be insulated on site. Polypropylene tanks have a temperature rating of 200 degrees F, but are not recommended for use with temperatures below freezing. Caution: When looking for plastic tanks for your solar water storage needs you need to avoid the more common Polyethylene tanks. The polyethylene tanks can only handle temperatures of around 120 degrees and would not be suitable for solar applications. With polypropylene tanks you need to concern yourself about shipping costs since the large tanks generally only come from a few facilities in the country. These tanks are middle of the road price wise for atmospheric storage tanks.

Atmospheric solar tanks made of welded mild steel are common. Inside the tank, the steel is first line with polyiso foam insulation, and then lined with the EPDM material. EPDM stands for Ethylene Propylene Diene Monomer. EPDM is a synthetic rubber that can be made in a variety of grades. Although manufacturers of EPDM lined tanks indicate that they have an indefinite lifetime and come with a warranty against leakage, many solar experts are concerned about EPDM for solar storage, stating that the material will deteriorate under the high temperatures of solar hot water systems. These tanks are generally the least expensive tanks overall.

All atmospheric solar
storage tanks are constructed of an outer layer to withstand environmental conditions, an inner layer of some type of insulating material to reduce heat loss, and an inner liner to reduce corrosion and extend the life of the tank. However, atmospheric solar storage tanks are constructed of many different types of materials.

Since large capacity tanks are difficult to maneuver through doorways, assembly of some atmospheric tanks is done at the installation site. This may reduce the shipping costs as well.

next – stainless steel tanks

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.