Solar Basics

This information may help assist you with understanding why solar energy is important to us, how the sun’s energy has been harvested for the benefit of all Australians and where to access solar products and other SolarEast products. Simply Click on the topic below to find additional information that may be useful for you.
Solar energy is the cleanest and most inexhaustible of all known energy sources. Solar radiation is the heat, light and other radiation that is emitted from the sun. Solar radiation contains huge amounts of energy and is responsible for almost all the natural processes on earth. The suns energy, although plentiful, has been hard to directly harness until recently.Solar Energy can be classified into two categories, Thermal and Light. Photo-voltaic cells (PV) use semiconductor-based technology to convert light energy directly into an electric current that can either be used immediately, or stored in a battery, for later use. PV panels are now becoming widely used as they are very versatile, and can be easily mounted on buildings and other structures. They can provide a clean, renewable energy source which can supplement and thus minimize the use of mains electricity supply. In regions without main electricity supply such as remote communities, emergency phones etc, PV energy can provide a reliable supply of electricity. The disadvantage of PV panels is their high cost and relatively low energy conversion rate (only 13-15%). Thermal solar on the other hand has average efficiency levels 4-5 times that of PV, and is therefore much cheaper per unit of energy produced.Thermal energy can be used to passively heat buildings through the use of certain building materials and architectural design, or used directly to heat water for household use. In many regions, solar water heaters are now a viable supplement or alternative to electric or gas hot water production.Thermal energy obtained from the sun can be used for a number of applications including producing hot water, space heating and even cooling via use of absorption chilling technology. Using solar and other forms of renewable energy reduces reliance on fossil fuels for energy production, thus directly reducing CO2emissions. CO2 emissions contribute to global warming, an environmental issue which is now of great concern. The average household can reduce CO2 emissions by as much as 20% by installing an Sunrain solar collector. Flat plate thermal solar collectors have been in use for several decades, but only in relatively small numbers, particularly in Western countries. Evacuated tubes have also been in use for more than 20 years, but have been much more expensive than flat plate, and therefore only chosen for high temperature applications or by those with money. In recent years the production volume of evacuated tubes has exploded, resulting in greatly lower manufacturing and material costs. The result is that evacuated tubes are now similar in price to flat plate, but with the insulating benefits of the evacuated tube, they are set to become the default choice for thermal solar applications worldwide.
What is solar insolation? The amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Basically that means how much sunlight is shining down on us. Why is knowing the insolation level useful? By knowing the insolation levels of a particular region we can determine the size of solar collector that is required. An area with poor insolation levels will need a larger collector than an area with high insolation levels. Once you know your region's insolation level you can more accurately calculate collector size and energy output. What units are used to express Insolation levels? The values are generally expressed in kWh/m2/day. This is the amount of solar energy that strikes a square metre of the earth's surface in a single day. Of course this value is averaged to account for differences in the days' length. There are several units that are used throughout the world. The conversions based on surface area as follows: 1 kWh/m2/day = 317.1 btu/ft2/day = 3.6MJ/m2/day The raw energy conversions are: 1kWh = 3412 Btu = 3.6MJ = 859.8kcalIs my region's insolation level low, moderate or high? The following scale is a basic guide for insolation levels. Although a value of 5 is not considered very high during the summer months, as an average annual value this is very high. You will see that in central Australia, which is a hot, sunny place, the annual average insolation is 5.89. You may compare you location to the following two extreme locations. Average annual insolation levels: Central Australia = 5.89 kWh/m2/day - Very High Helsinki, Finland = 2.41 kWh/m2/day - Very Low
To achieve maximum solar performance, the solar collectors should be installed facing as close to North as possible. The following are guidelines for the installation of solar collectors:
  • Solar collectors should be positioned to face the equator which is North facing in Australia. The further away from North, the greater the loss in solar efficiency.
  • The inclination of the solar collectors should be within 10% either side of the local latitude angle. For example, the latitude of Brisbane is 270 South so the inclination of the solar collectors should be approximately 24 to 30 degrees.
  • Solar collectors should be free from shading by trees (should be checked regularly) or nearby buildings or other structures.Note: If the above guidelines cannot be achieved, consideration should be given to increasing the solar collection area by adding an extra solar panel, particularly if the direction is further than 450 either side of North.In any case, no direction should be chosen that has any inclination towards South.
CERTIFICATION Australia’s WaterMark approval ensures compliance with Australian Standards and continual quality and process control for all materials in contact with our potable water system and is recognise around Australia. IAPMO Oceana Certification for solar Products and systems is mandatory for application with Australia’s Clean Energy Regulator for the granting of STC’s CE CERTIFICATION CE Certification is the European Conformity standard for solar collectors. Sunrain has obtained certification through Global Mark. SOLARKEYMARK CERTIFICATION Solarkeymark is the most widely accepted European standard for solar thermal. Testing for the certificate was completed by ITW and ISE in Germany. SRCC CERTIFICATION The SRCC (Solar Rating and Certification Corporation) is the key solar collector certifying body for the US and Canada. The Sunrain solar collector has been tested in Canada and Florida and obtained SRCC certification. AUSTRALIA STANDARDSMARK The five ticks StandardsMark is Australia’s most recognized certification mark providing competitive advantage and differentiation to each product carrying this mark. The Sunrain solar collector has been tested in Australia and obtained StandardsMark certification. SOUTH AFRICAN BUREAU OF STANDARDS SABS in South Africa as a neutral third-party certification body responsible for South Africa's system certification and product certification. Sunrain TZ47/1500-18T solar water heating system complies with SABS and has obtained the certification. CSA CERTIFICATION GSE IP-195 Solar Water Heating System has been certified by CSA, and it is now the first and the only CSA certified evacuated tube solar water heating system in Canada KOREA CERTIFICATION Korea Certification is the Korea standard for solar collectors. Sunrain has obtained certification through Global Mark. CHINA CCC CERTIFICATION China CCC Certification is the Peoples Republic of China standard for solar collectors. Sunrain has obtained certification through Global Mark.
CONTACT TO CONTACT US, PLEASE JUST SEND US AN E-MAIL AND MENTION YOUR REQUEST. WE WILL THEN GET IN TOUCH WITH YOU. YOU CAN ALSO REACH US BY TELEPHONE OR FAX. CLICK HERE to access our customer enquiry form. Simply complete it and submit and we will reply as soon as possible SolarEast SolarEast Australasia Pty Ltd 2/10-12 Cerium Street, Narangba, Queensland 4504 PO Box 265 Beachmere Queensland 4510 P: 1300 668 886  l  M: + 61 (0)400 98 4243 Email: Web:
Your plumber or builder can help you decide whether flat plate technology or evacuated tube technology will be best in your area. SolarEast’s advice is to only install flat plate panels in frost free areas. A number of configurations of tank size (270L, 340L and 450L) are available along with 2 and 3 flat plate panel configurations or 20/25/30 and 40 tube evacuated tube configurations. It is also important to appreciate your family needs will change over time and plan ahead either for increased usage or perhaps decreased usage of hot water Some factors to be considered are:
  • Increased family usage as children become older
  • Number of bathrooms and whether these bathrooms will be used concurrently
  • Water saving appliances and shower heads
  • Appliances connected – some dishwashers and washing machines will use hot water
  • Your climate and water pressure can influence usage
As a general guide only, the following table may be useful. Note that the above represents a guide only and additional advice should be taken from your installing plumber
SOLAR GLOSSARY Here are a list of some terms you may encounter when reading through our web site. We have tried to make explanations as easy to understand as possible, but if you are still un-clear please feel free to contact us. A-B-C-D-E-F-G-H-I-P A Aperture: The part of the collector through which light enters. For evacuated tubes this refers to the cross-sectional surface area of the outer clear glass tube measured using the internal diameter, not the outside diameter. (Eg. 0.0548m x 1.72m = 0.094m2). 1.72m is the exposed length of the evacuated tube. Absorber: The part of the collector that actively absorbs the light rays. For solar tubes this is defined as the cross-sectional area of the inner tube (selective coated) measured using the outside diameter. (Eg. 0.047 x 1.72m = 0.08m2) This value is used when calculating efficiency values. For solar tube collectors with reflective panels, the entire circumferential surface area of the inner tube is often used when calculating absorber area, as the reflective panel is supposed to reflect light onto underside of the evacuated tube. The Sunrain solar collector does not use reflective panels. B BTU - Stands for British Thermal Units. This is an imperial unit of measurement for heat widely used in the US and also in the UK. The conversion to the metric unit kWh is: 1 kWh = 3412Btu, and for surface area values, 1kWh/m2/day = 314Btu/ft2/day C Collector - A solar collector is not really a solar water heater. A solar water heater is a system which may include a tank, pump, controller and solar collector panel. A solar collector is that part of the system which absorbs the sun's energy and converts it into heat. The Sunrain AP model is separate from the tank as so is a solar collector. Celsius - The metric unit for temperature measurement. Convert as follows: Fahrenheit = (oC x 1.8) + 32 Celsius = (oF - 32)/1.8 For Delta-T measurements the relative temperature difference is needed. Eg. Delta-T = 7oC turn pump on, Delta-T 2oC turn pump off. How much is that in oF?? The conversion from Fahrenheit to Celsius is simple: Fahrenheit = oC x 1.8 Celsius = oF / 1.8 D Delta-T Controller: Delta-T refers to the difference in two temperatures. This term is often use in relation to a solar controller. In such case the Delta-T is the difference between the solar collector temperature and the temperature of the water in the solar storage tank. A Delta-T controller can be configured to turn on the pump when the Delta-T difference exceeds a certain level (Eg.7oC / 12.7oF) and off again when the temperature difference drops below another setting (Eg. 2oC / 3.6oF). The controller turns on the pump when there is heat potential in the manifold. A Delta-T controller can also be used to provide freeze protection by circulating warm water from the tank through the manifold when the manifold temperature drops below 5oC. E Efficiency: Solar collector efficiency is usually expressed as a percentage value, or in a performance graph. When assessing a collector's performance make sure it is based on the correct surface area values. Eg. If performance values are based on gross area, then the gross area must be used when determining total heat output. IAM values have a significant influence on actual heat output throughout the day, and should be considered. Looking at just the percentage efficiency value will not give a true indication of daily heat output. Efficiency testing is usually completed by testing bodies such as SPF, SRCC and other government approved testing bodies. Tm* is the x axis value on performance graphs for solar collectors. Tm* is calculated as: (water temp - ambient temp)/Insolation Eg. (44oC - 20oC)/800Watts = 0.03 F Flow Rate: The volume of water flowing through plumbing in a given period of time. Usually measured in volume/minute or volume/hour. 1 Litre/min = 0.264 US Gallon/min G Gross Area: The total surface area of the collector including the frame, manifold and absorber. This area is often used when comparing collectors, but a better comparison to use is value for money. Roof size is not usually a limiting factor for domestic solar water heating installations, so the size of the collector is not really that important. H Heat Pipe: An evacuated rod or pipe used for heat transfer. I Insolation: Don't confuse this with insulation - the one letter change makes a big difference. Insolation refers to the amount of sunlight falling on the earth. Insulation: The ability to protect against transfer of heat/cold. Sunrain solar collectors use compressed glass wool to insulate the header from heat loss. Glass wool has excellent insulation properties, is very light and can withstand high temperatures, making it an ideal choice for a solar collector. It is made from a least 80% old glass bottles and can be recycled so is very environmentally friendly. Irridance, Irridation: Basically the same as Insolation - explained above. Incidence Angle Modifier (IAM): refers to the change in performance as the sun's angle in relation to the collector surface changes. Perpendicular to the collector (usually midday) is expressed as 0o, with negative and positive angles in the morning and afternoon respectively. Collectors with a flat absorber surface, which includes some types of evacuated tubes, only have 100% efficiency at midday (0o), whereas Sunrain solar tubes provide peak efficiency mid morning and mid afternoon, at around 40o from perpendicular. This results in good stable heat output for most of the day. P Pressure: Refers to the water pressure in the system. The conversions for the most commonly used units are: 1 bar = 1.02kg/cm2 = 14.5psi = 100kPa = 0.1Mpa = 10m water head
Heat pipes might seem like a new concept, but you are probably using them everyday and don't even know it. Laptop computers often using small heat pipes to conduct heat away from the CPU, and air-conditioning system commonly use heat pipes for heat conduction. The principle behind heat pipe's operation is actually very simple. Structure and Principle The heat pipe is hollow with the space inside evacuated, much the same as the solar tube. In this case insulation is not the goal, but rather to alter the state of the liquid inside. Inside the heat pipe is a small quantity of purified water and some special additives. At sea level water boils at 100oC (212oF), but if you climb to the top of a mountain the boiling temperature will be less that 100oC (212oF). This is due to the difference in air pressure. Based on this principle of water boiling at a lower temperature with decreased air pressure, by evacuating the heat pipe, we can achieve the same result. The heat pipes used in AP solar collectors have a boiling point of only 30oC (86oF). So when the heat pipe is heated above 30oC (86oF) the water vaporizes. This va pour rapidly rises to the top of the heat pipe transferring heat. As the heat is lost at the condenser (top), the va pour condenses to form a liquid (water) and returns to the bottom of the heat pipe to once again repeat the process. At room temperature the water forms a small ball, much like mercury does when poured out on a flat surface at room temperature. When the heat pipe is shaken, the ball of water can be heard rattling inside. Although it is just water, it sounds like a piece of metal rattling inside. This explanation makes heat pipes sound very simple. A hollow copper pipe with a little bit of water inside, and the air sucked out! Correct, but in order to achieve this result more than 20 manufacturing procedures are required and with strict quality control. Quality Control Material quality and cleaning is extremely important to the creation of a good quality heat pipe. If there are any impurities inside the heat pipe it will effect the performance. The purity of the copper itself must also be very high, containing only trace amounts of oxygen and other elements. If the copper contains too much oxygen or other elements, they will leach out into the vacuum forming a pocket of air in the top of the heat pipe. This has the effect of moving the heat pipe's hottest point (of the heat condenser end) downward away from the condenser. This is obviously detrimental to performance, hence the need to use only very high purity copper. Often heat pipes use a wick or capillary system to aid the flow of the liquid, but for the heat pipes used in Sunrain solar collectors no such system is required as the interior surface of the copper is extremely smooth, allowing efficient flow of the liquid back to the bottom. Also Sunrain heat pipes are not installed horizontally. Heat pipes can be designed to transfer heat horizontally, but the cost is much higher. The heat pipe used in Sunrain solar collectors comprises two copper components, the shaft and the condenser. Prior to evacuation, the condenser is brazed to the shaft. Note that the condenser has a much larger diameter than the shaft, this is to provide a large surface area over which heat transfer to the header can occur. The copper used is oxygen free copper, thus ensuring excellent life span and performance. Each heat pipe is tested for heat transfer performance and exposed to 250oC (482oF) temperatures prior to being approved for use. For this reason the copper heat pipes are relatively soft. Heat pipes that are very stiff have not been exposed to such stringent quality testing, and may form an air pocket in the top over time, thus greatly reducing heat transfer performance. Freeze Protection Even though the heat pipe is a vacuum and the boiling point has been reduced to only 25-30oC (86oF), the freezing point is still the same as water at sea level, 0oC (32oF). Because the heat pipe is located within the evacuated glass tube, brief overnight temperatures as low as -20oC (14oF) will not cause the heat pipe to freeze. Plain water heat pipes will be damaged by repeated freezing. The water used in Sunrain heat pipes still freezes in cold conditions, but it freezes in a controlled way that does not cause swelling of the copper pipe.
EVACUATED TUBES Evacuated tubes are the absorber of the solar water heater. They absorb solar energy converting it into heat for use in water heating. Evacuated tubes have already been used for years in Germany, Canada, China and the UK. There are several types of evacuated tubes in use in the solar industry. Sunrain collectors use the most common "twin-glass tube". This type of tube is chosen for its reliability, performance and low manufacturing cost. Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures. This "evacuation" of the gasses forms a vacuum, which is an important factor in the performance of the evacuated tubes. Why a vacuum? As you would know if you have used a glass lined thermos flask, a vacuum is an excellent insulator. This is important because once the evacuated tube absorbs the radiation from the sun and converts it to heat, we don't want to lose it!! The vacuum helps to achieve this. The insulation properties are so good that while the inside of the tube may be 150oC / 304oF , the outer tube is cold to touch. This means that evacuated tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta-T conditions). In order to maintain the vacuum between the two glass layers, a barium getter is used (the same as in television tubes). During manufacture of the evacuated tube this getter is exposed to high temperatures which causes the bottom of the evacuated tube to be coated with a pure layer of barium. This barium layer actively absorbs any CO, CO2, N2, O2, H2O and H2 out-gassed from the evacuated tube during storage and operation, thus helping to maintaining the vacuum. The barium layer also provides a clear visual indicator of the vacuum status. The silver coloured barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition. See picture below.  
The Getter is located at the bottom of the evacuated tube. Left Tube = Vacuum Present Right Tube = Faulty
Evacuated tubes are aligned in parallel, the angle of mounting depends upon the latitude of your location. In a North South orientation the tubes can passively track heat from the sun all day. In an East West orientation they can track the sun all year round. The efficiency of a evacuated water heater is dependent upon a number of factors, one important one being the level of evacuated radiation (insolation) in your region. To learn more about insolation and the average values for your area click here. Evacuated Tube Basic Specifications
Length (nominal) 1500mm /1800mm
Outer tube diameter 58mm
Inner tube diameter 47mm
Glass thickness 1.6mm
Thermal expansion 3.3x10-6 oC
Material Borosilicate Glass 3.3
Absorptive Coating Graded Al-N/Al
Absorptance >92% (AM1.5)
Emittance <8% (80oC)
Vacuum P<5x10-3 Pa
Stagnation Temperature >200oC
Heat Loss <0.8W/ ( m2oC )
Maximum Strength 0.8MPa
Solar Water Heating Reduces CO2 Emissions Currently Sunrain solar collectors are reducing CO2 emissions by more than 13,000 tonnes / 28.6million pounds per year, with collectors installed in the UK, USA, New Zealand, Germany, France, Sweden, Italy, Hungary, Portugal, Jordan, Lebanon, Australia, Canada, Mexico and many other locations. (One metric tonne = 2200 pounds) There has been a great deal of information in the media over the past few years about global warming and the role of CO2 emissions. 2003 saw extreme weather conditions and a heat-wave throughout Europe, clear evidence of the realism of this problem, commonly referred to as the "greenhouse effect." Burning fossil fuels such as coal for electricity production, and gas for water heating both release large amounts of CO2 into the atmosphere, thus contributing to this environmentally harmful phenomenon. By using renewable energy sources such a Solar Thermal, Solar PV, Wind, Hydro and Geothermal, reliance on fossil fuels can be minimised, thus directly reducing CO2 emissions. On average for every 1kWh of energy produced by a coal power station, 1kg (2.2pound) of CO2 is produced. Burning natural gas for electricity production or water heating produces about 450grams of CO2 for every kWh of energy produced. In the average household, water heating accounts for around 30% of CO2 emissions. By installing a solar water heater, which can provide between 50-70% of your hot water heating energy needs, you can reduce your total CO2 emissions by more than 20%.