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Choosing a solar hot water system
 

Choosing a solar hot water system

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A detailed document on choosing a new solar hot water systems. The article discusses the types of solar systems available, site and installation considerations, rebates, return on investment etc.

A detailed document on choosing a new solar hot water systems. The article discusses the types of solar systems available, site and installation considerations, rebates, return on investment etc.

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    Choosing a solar hot water system Choosing a solar hot water system Document Transcript

    • CHOOSING A SOLAR HOT WATER SYSTEMPurchasing a solar hot water system is one of the best things any homeowner can do to reduce household energy costs and Co2 emissions. Learnabout the different types of SHW systems and which one will suit you and By: David Payne Enviro Friendly World
    • Choosing a Solar Hot Water SystemTable of Contents Types of Solar Hot Water Systems: ........................................................................................................ 3 Evacuated Tubes ..................................................................................................................................... 3 Heat Pumps .............................................................................................................................................. 3 Flat Plates ................................................................................................................................................. 3 Configuration Type 1: Close Coupled Systems ...................................................................................... 3 Configuration Type 2: Split Systems ...................................................................................................... 4 Collector Type 1: Flat Plates ................................................................................................................... 4 Collector Type 2: Evacuated Tubes ........................................................................................................ 5 Key Advantages ....................................................................................................................................... 5 Collector Type 3: Heat Pumps ................................................................................................................ 6 Reduction in Energy Use: ........................................................................................................................ 7 The Ideal Roof Orientation ..................................................................................................................... 8 Roof Pitch: ................................................................................................................................................ 8 Shading Considerations: ......................................................................................................................... 9 Frost and Freezing: ............................................................................................................................... 10 Backup Booster Options: ...................................................................................................................... 11 Installation: ............................................................................................................................................ 12 Tempered Solar Hot Water ................................................................................................................... 12 Solar Hot Water Rebates: ...................................................................................................................... 13 In Conclusion: ........................................................................................................................................ 13 About the Author: .................................................................................................................................. 14 1 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemWhy Buy and Install a Solar Hot Water System? Choosing to install a Solar Hot Water System is one of the best financial decisions you can make when it comes to upgrading your home or business, and reducing your energy use and cost. As I write this article, world CO2 atmospheric levels top 396ppm, and Australians are looking at another major price rise in the retail cost ofelectricity in July.In this article I discuss the different types of solar hot water systems (SHWSs) available,including flat plates, evacuated tubes and heat pumps, and the considerations you need totake into account in choosing the best one for you.The banning of electric storage hot water systems throughout Australia during 2012 hasmade needing to know what systems are available, and which will best suit your home,more important than ever.Every day your home or business keeps using that old electric storage hot water system, isanother day that you don’t benefit from the lower running costs, improved property value,and lower CO2 emissions, provided by a well designed and installed solar system. Subjectsthat I’m sure you will agree are becoming more and more important to us all.I hope you find the information provided in this article of value, and that you’ll soon jointhe millions of people around the world enjoying all the benefits of solar.Kind regardsDavid PayneJune 2012 2 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemTypes of Solar Hot Water Systems:Solar Hot Water Systems come in two main configurations, Close Coupled (tank on roof) orSplit Systems (tank on the ground). I shall also discuss Heat Pumps which are seen bymany as solar based technology. Evacuated Tube Heat Pumps Flat PlateConfiguration Type 1Close Coupled SystemsThese offer lower running costs (excluding boosting) as they don’t require any electricity tomove the water from the collector to the storage tank, taking advantage of natural“thermosiphoning”. The trade-off is a bulker unit with higher system weight on the roof.For example, a 300L storage tank holds 300kg of water + tank and collector weight. 3 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemConfiguration Type 2:Split SystemsSplit Systems have the collector on the roof and the storage tank located somewhere else-normally on the ground. Split Systems require the use of solar pumps and controllers tomonitor temperatures, and move water from the collector(s) to the storage tank. This doesinvolve small amounts of energy being used -- normally around 28-60 watts per hour forup to 8+ hours a day.Collector Type 1:Flat PlatesThe first widely available Solar Hot Water Systems in Australia were designed in WesternAustralia way back in 1953 by Solarhart, with their flat plate technology. This became thestandard design for SHWSs for the next 40 years. Flat plates use a large collector surface topick up the Sun’s heat with water pipes embedded in the collector to transfer heat. Thecollector surface is protected by a sheet of glass or plastic that generally offers little to noinsulation. 4 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemCollector Type 2Evacuated tubesIn the mid-1970s the University of Sydney developed evacuated tube systems but it was to beanother 25 years before evacuated tubes became widely available in Australia. Thistechnology provides the highest performance per sq. m. available to the domestic market.Evacuated tubes take advantage of the naturalinsulation properties of a vacuum, which allows heatto enter the glass tube, but then doesn’t allow thatheat to escape back into the atmosphere.The use of a vacuum also gives evacuated tubesnatural frost protection, with no need for antifreezeadditives like glycol that can also reduce performanceby up to 10%, and create ongoing maintenance needs.Because the evacuated tubes are round, passive tracking of the sun across the sky allows alarge collection surface to be perpendicular to the sun and provide greater performance.Key Advantages • Naturally frost protected down to -10°C or greater • Passive sun tracking for greater performance • Low on roof weight • Modern stylish design. • No Glycol (antifreeze) needed 5 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemCollector Type 3:Heat PumpsAre Heat Pumps really solar systems?Well yes and no…….. But if you have major shading issues they are a great alternative energyefficient solution.While heat pumps do not use the direct radiant energy from the sun as both flat plate andevacuated tube systems do, they do derive a large percentage of their energy from the heaton the atmosphere that’s created by the sun.Heat pumps use a compressor to extract heat from the atmosphere and transfer the heatinto a water storage tank. It does this very efficiently with a typical system producing about3kw of rated energy for every 1kw of power used at around 20°C.Key Benefits • Does not require direct sunlight. Can even be located in permanent shade. • No on-roof installation. • More efficient than electric storage systems, even at low temperatures. • Can take advantage of waste heat from such things as roof spaces and plant rooms. • Are rebated by some government agencies and renewable energy programs. • Lower installation costs than on-roof systems. 6 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemReduction in Energy UseHeating your home’s hot water is on average around 30% of the total amount of energyused by domestic homes each year, and with the rising cost of electricity now a majorfactor in household budgets, moving to solar hot water should be at the top of people’shome upgrade options list.“We think that, by 2020, the cost of electricity will be threefold what it is today,..”Origin Energy Chief Executive- The Australian 14/04/2010 Example of possible return on invest factoring in a 10%pa rise in the cost of energyReplacing an old electric HWS with a SHWS could reduce your HW energy costs by up to90%, as well as adding value to your home. A natural gas boosted evacuated tube systemoffers the lowest running costs but does come at a higher cost for purchase and installation.Savings for an average family of four in Australia is estimated to be over $700 p.a., andsaves about four tonnes of CO2 if replacing an electric boosted hot water running on maintariff power. That can equate to well over a 15% return on your investment (ROI).Replacing an old electric HWS with a solar hot water system could... • Reduce your hot water energy consumption by up to 90% • Add value to your home. • Reduced energy bills. • Rebates still available (See Solar Hot Water Rebates). • Lower you greenhouse gas emissions. • Can offer a far greater ROI over other investment options. 7 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemThe Ideal Roof Orientation:Solar orientation is one of the biggest factors effecting solar hot water performance. In thesouthern hemisphere, a SHWS’s ideal orientation is due North, with the reverse being truein the northern hemisphere. The further a system is from due north, the less energy it willbe able to harness.Not all technologies handle having their orientation off true north as well as others.Evacuated tubes with their cylindrical tube design allow for greater performance over flatplates, as the degree of orientation from true north increases right up to 90° with minimalperformance loss.Roof Pitch:The pitch of your roof does affect the performance of a solar hot water system, and shouldbe taken into account when designing any system. In Australia, typical domestic roof pitchis between 22.5° and 25°, but many homes have a higher or lower roof pitch. Generally thehigher the roof’s pitch, the better winter performance will be, and is recommended overlower pitches that increase summer performance.To find the optimum pitch for your SHWS, take the latitude of the home location, then addbetween 10°-20°. To comply with AS/NZS 3500.4:2003, a collector’s incline angle ofdeviation is not to be greater than ±20° from the latitude of the installation location. E.g.:Canberra lies at a latitude of 35°, so the optimum winter angle would be 55°For roofs that have pitches lower than 20°,you should have the system placed on aframe to raise the pitch to the optimumangle. The additional cost of the frame willmore than be made up for by the increasedperformance of the system. 8 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemShading Considerations:The shading of a solar hot water system has the single biggest effect on the performance ofthe system throughout the year. You should always try to have the unit installed in alocation where there is minimal or no shading.Trees are one of the two main causes of shading and typically have a great effect duringwinter when the sun is lower to the horizon. Trees are generally only a major issue inwinter, and deciduous trees are better than native Australian trees that don’t drop theirleaves during winter. Trees in most cases can be cropped or removed to give better solaraccess, but this does depend on factors such as property ownership etc. Ensure winter shading is minimalBuildings of two stories or more in height that are adjacent to the solar hot water systemcan have a dramatic and permanent impact on performance, and should be taken intoaccount before proceeding with any installation. If shading is an issue and another locationfor the installation cannot be found, then Heat Pump technology should be considered as itdoes not rely on direct heat from the sun.Owners of homes that lie in valleys where there is the likelihood of significant shadingduring winter months in particular, should consider carefully before choosing to install anon-roof solar hot water system. This type of situation is another good candidate for HeatPump technology. 9 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemFrost and Freezing:In areas where frost and snow are factors during winter, not all solar hot water systems arethe same. If you live in a frost-prone area, careful consideration should be given as to whichtechnology to employ.Evacuated tubes have by design passive frost protection, and typically handle temperaturesdown to -10°C - 15°C with no loss in performance, or additional need for frost protection.Quality evacuated tubes do not have any water passing through the glass tubes themselves,and are protected by the vacuum area of the tube, which does not allow heat to escape backinto the atmosphere. Most evacuated tube systems do have some form of frost protectionbuilt in for the piping that pumps small amounts of water from the storage tank to thecollector drops during periods of below zero temperaturesFlat plates typically had no insulation between the glass and collector surface, and as suchhave required some form of active frost protection. Older flat plate systems used heatingelements in the collector, that heated the water when temperatures dropped below 0°c.Heating elements use significant amounts of energy, and negate much of the solar benefit.Most flat plate systems use Glycol as antifreeze to avoid freezing the collector(s), and thisdoes come at a performance loss of up to 10%. Glycol also requires maintenancethroughout its life at additional cost to home owner, and lack of maintenance may in manycases void warranties.Over the past couple of years hybrid systems using combinations of flat plate and heat pipetechnology have started to enter the market, and offer far better performance over glycolflat plate systems. 10 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemBackup Booster options:All solar hot water systems require some form of backup booster. This is because there aretimes throughout the year when even the very best solar hot water system is not able tosupply water at the desired temperature. Backup boosters come in two main forms,Electric Element or Gas.Gas-boosted solar hot water systems come in a few different configurations, which one youchoose will depend on your situation. Condensing natural gas boosters are the mostefficient systems, as they only heat water coming from storage if the water temperature isbelow a set level. Gas storage systems have a burner in the base of the tank ,that will usemore energy than condensing gas systems, but can be a less costly option initially. In areaswere natural gas is not available, bottled LPG can be used for both storage and instant gassystems, but does have higher running costs. Gas boosted Solar Electric Boosted SolarElectric-boosted systems typically use a heating element to heat any water that’s not ableto reach ideal operating temperatures. Most elements draw around 3.6kw per hour, and dorequire control on the times of day the booster may come on, so as not to “compete” withthe solar collector.It is recommended that the electric booster be connected to Off-Peak power that onlyallows for boosting during the night. If off-peak is not available then a timer can be used.Many Energy utilities offer various Off-peak plans, be sure not to select a plan thatallows for boosting during daylight hours. 11 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemInstallation:All SHWSs in Australia must be installed by a licenced plumber/gas fitter, and comply withall state and territory codes and standards. Not all plumbers are the same, and one shouldalways choose a plumber/installer that has experience with the technology you choose, aseach technology has its own particular requirements.Tempered solar hot waterAll new hot water systems in Australia are required by law to be “tempered” to a maximumof 50°C to all bathrooms in the home; this is done by using a tempering valve that mixescold water into the hot water line, to achieve the desired temperature. This is a safetyfeature designed to protect children and adults from accidental scalding. A high qualitysolar system can have hot water temperatures as high as 90°C during summer. Laundriesand kitchens can be untempered but is not recommended and comes at additional cost.Solar Rated Tempering valveSolar rated InsulationInstallations in cold or frost prone areas should always use quality solar rated pipeinsulation (lagging), not only for any pipework exposed to the atmosphere, but also on anypipework inside walls and roof cavities.Roof system weightWhen installing a “close coupled” solar hot water system in/on your roof, it’s advisable tocheck if the roof structure can handle the substantial extra weight of these systems. Theweight can be in excess of 500kg+. If weight is a problem then a “Split System” should beused, giving a much lower on-roof weight. 12 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemSolar Hot Water Rebates:Solar Hot Water Rebates have been widely available from Local, State, Territory andFederal Governments, as a way of encouraging the uptake of solar that typically havehigher purchase and installation costs. Rebates are generally only available for completesystems that have been tested by accredited testing laboratories.Over the past few years we saw the peak on rebates for SHWSs reached, with combinationsof rebates from various governments sometimes being available. Recently we have seen areduction in available rebates, as well as a reduction in rebate values, as new buildingcodes, the banning of older technologies like electric storage hot water systems etc isimplemented. In many cases one or more rebates may be available and your retailer shouldbe able to provide you with the full details of all rebates for solar hot water in your area.In Australia the Federal Government has set up a testing and approval program for systemsclassed as solar hot water or heat pumps, and applies Renewable Energy Certificates(STC’s) based on the tested efficiency of each system. STC’s can only be created once asystem has been installed. STCs can then be sold on the REC-registry market in return for adollar amount. The value of each STC is based on market forces, and varies over time.Example of STC’s on cost of systemSystem cost $4000.00No of STC’s 30Value per STC $34.00Total STC value $1020.00System cost after STC’s $2980.00The rising cost of energy is increasingly putting pressure on households. With or withoutrebates, installing a solar hot water system on your home is fast becoming one of greatestchanges you can make to reduce your electricity and gas costs, offering a great return onyour investment.The Economics of Solar Hot Water:The savings made by installing a solar hot water system, and the Return on Investment(ROI) achieved, vary from family to family, place to place, and system to system. But to givea simple example, if a system cost $4000 all-up to purchase and install, and saves yourfamily $700 in the first year,  That’s a tax-free Return (ROI) of 17.5%  If your marginal tax rate is 40%, you’d have to get a 29% pre-tax ROI elsewhere to match your solar hot water investment. There aren’t many of those around.  That’s just your ROI in Year One. Every year electricity goes up, so does your ROI. 13 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012
    • Choosing a Solar Hot Water SystemIn Conclusion:Thank you for taking the time to read this article on choosing a solar hot water system. Ihope you found it informative. I have been involved in the design, sales and installation ofsolar hot water systems for over 8 years.With the need to address global warming, the introduction of carbon taxes, and pressure onour aging utility infrastructure, installing a solar hot water system is not a only a greatinvestment for your home or business, but also for the wider community.If you would like to learn more on Solar Hot Water for your home, please visit www.enviro-friendly.com and our Enviro Friendly Blog.If you would like obligation-free Quotes for installing solar hot water, click here.To read the latest version of Choosing A Solar Hot Water System, click here.About the Author:Name: David PayneAge: 39Location: Canberra AustraliaProfile Page: gplus.to/DavidPayneContributes to: Enviro-friendly.com/blogBrief Bio:Together with his Father John, David started a sustainable products company in 2002selling rainwater tanks. In 2004, David was one of the first retailers to promote and sellevacuated tube solar hot water systems in Australia. David has extensive experience inboth domestic and commercial solar hot water, photovoltaic systems, and rainwaterharvesting. 14 Choosing a Solar Hot Water System © CASA PAYNE Pty Ltd 2012