Solar Power Explained
All you want to know about Solar Power
|Solar hot water systems use the heat from the sun wheras solar electricity uses sunlight. Solar Photovoltaic (PV) is a technology that uses sunlight to generate direct current (DC) electricity. Solar thermal systems, also know as solar hot water systems create hot water and use a completely different technology. Solar hot water panels usually have copper pipes running through them filled with water. The water is simply heated by the sun, and the hot water flows into a storage tank. Sometimes. like in this photo the storage tank is on the roof, sometimes the tank is on the side of the house. In the case of a solar hot water system the sun's energy is used to heat the water. It works similar to the heating of water in a hose lying on the grass on a hot summer's day.|
PV solar panels (in background of photo) generate a flow of electricity when hit by sunlight . This generated electrical energy when harnessed and send through an inverter is converted into usable electricity for electrical appliances. LG manufactures solar panels (LG's automated solar factory) to generate electricity and does not manufacturer solar hot water systems, like the one in this photo.
A solar module is made up of a group of photovoltaic cells. They consist of 2 layers of silicon wafers which become positively and negatively charged when sunlight hits them. The charge created flows through a circuit of small wires connected to the wafers.
The PV modules generate DC electricity and send it to the solar power inverter. The inverter transforms the DC power (Direct Current) from the modules into AC electricity (Alternating Current) and feeds it back to the power grid, ready to be used in the house or exported back into the grid/power poles.
Good data is available which enable us to predict how much solar irradiation will be available throughout the year across the entire planet and thus, predicting the likely annual output of your solar power system.However, a number of variables can affect the performance levels of your solar system. Have a look at the potential electricity generation in your area via our calculator.
The first is the geographic location of the solar system. Depending on your latitude, a different amount of energy will be available because your location effect’s how perpendicular the sun is and also, how much atmosphere the sunlight needs to travel through to reach you. Australia happens to have one of the best latitudes in the world for solar energy.
A secondary effect is local geography, which can affect how much cloud cover or smog is typical. Although solar panels still produce electricity in cloudy or smoggy conditions, the clearer the sky the better the energy production will be. As a rule of thumb, on a cloudy day a solar system will produce around 20% to 35% of the energy it would produce under ideal conditions.
The second major impact on solar generation is the time of year or season. During the changing seasons the earth rotates on its axis changing the perpendicularity of the sun and thus the intensity of the energy reaching us. Logically, it is strongest in summer and weakest in winter and this will affect the performance of solar systems.
By using good data and taking into account location, seasons and geography we can estimate the average annual energy that will be produced, although the day to day levels may vary slightly. From year to year there is some variation but generally sunlight intensity and therefore annual energy production is relatively predictable. Normally orientation of panels, overshadowing or efficiency of solar panels and inverter all contribute to the final renewable electricity generated.
Try our solar calculator to estimate how much electricity various size LG solar system could generate in your area.
There are a number of different types of systems available in the market, the major ones being On Grid System, Off Grid System and Combination Systems, are detailed below:
1) On Grid Solar Power System
The most common type of solar systemOn Grid Solar Power System: This system is where solar electricity is connected to an existing grid power supply and is popular because instead of using batteries for storage, electricity is imported and exported to the grid as generation and demand varies. This helps reduce the cost and complexity of the solar power system.
On Grid solar power systems use inverters to convert the electricity produced by solar panels to the same voltage and frequency as grid power and to synchronise the systems together. The system also incorporates safety devices which allow solar systems to be isolated automatically if the grid is shut down for safety or maintenance purposes.
On Grid systems constantly monitor the voltage and frequency of the grid and specific standards exist to ensure that solar systems comply with this in Australia and around the world. This is one reason why choosing a high quality inverter is important. Lower quality inverters can suffer “trip-outs” if the grid power is varying and therefore your solar system temporarily shuts down. Higher quality solar inverters are better able to cope with grid power fluctuations and keep you connected for longer periods, giving you a better solar power output.
One implication of this type of system is that if there is a grid blackout, your solar system will not be able to supply your home with electricity, despite the fact that the solar panels may still be generating energy, unless you have an On Grid Support system which has storage battery support.
2)On Grid Solar Power System with storage battery support
Although not widely used yet, On Grid Support systems are gaining popularity. They are a combination of an On Grid system, with more sophisticated electronic control equipment and storage, typically in the form of on-site batteries.
The main feature of these systems is that in the event of a blackout or poor grid power quality, an On Grid support system can disconnect your home from the grid, then reactivate your solar system to provide power to your home via the batteries.
Such systems will automatically combine solar energy being generated from the solar panels and energy stored in batteries and provides energy to dedicated circuits within the home, in a similar way to Un-interruptible Power Supplies that are used on computers or operating theatres in hospitals.
3)Off Grid Systems
Off Grid systems are used where grid power is unavailable such as remote farms or homes, telecommunications sites, water pumping (see sample photo) or other remote industrial facilities.
Off Grid systems need to be very carefully designed to match energy generation to energy demand and require a detailed energy audit and site specific assessment to work effectively.
Off Grid systems use batteries to store solar energy so it is available to be used 24 hours a day and often include a back-up generator for unusually high energy demands or long periods of low solar irradiation. Whilst it is possible to operate such systems without a back-up generator, great care must be taken to ensure the energy demand is matched to the amount of energy stored in the batteries.
Off Grid solar power have been particularly useful int third world countries and remote Australia.
Telstra was one of the early users of off grid solar power systems in Australia using it for remote repeaters in place of generators; thousands of systems have been deployed across Australia stretching right back to the mid 1970’s and the Australia’s telephone system in remote locations still utilises solar electricity.
Many remote homesteads, farms and industrial sites use solar electricity in Australia as a cost effective and reliable alternative to diesel generation for household electricity, water pumping and agricultural uses. Solar electricity can significantly reduce the difficulties associated with getting fuel, maintaining complex generators and are virtually silent.
Off Grid solar systems are used in a huge variety of applications and are often life changing experiences for people in areas where little or no electricity was previously available.
Some of the applications in remote locations include:
- Power for villages, homes and farms
- Water pumping
- Water purification
- Vaccine refrigeration
- Electric fences
- Industrial applications
- Disaster relief
These are not commonly available in Australia due to the availability of regular electricity supply and electricity regulations. This type of solar systems are more common in developing nations where due to erratic supply of electricity these type of solar power systems ensure that basic requirements such as lights or refridgerators continue to work.
In these systems the solar power is connected to the grid through a battery back-up system. These batteries can be charged through the solar panels or from the grid. In case of electrical failure the batteries then power the home.
Solar electricity can be used in virtually any application where electricity is required, from powering simple household electrical items to running entire cities. However, because solar electricity is generated only when the sun shines it is typically either stored in batteries or used to supplement other forms of electricity, such as grid power or generator power.
Like any product, not all manufacturers' solar panels are equal. Some use the best quality materials and equipment to manufacture them and others do not.
Some manufacturers conduct extensive research and development into long term performance and have deep understanding of how the materials will behave and others do not. Some manufacturers have decades of experience in manufacturing electronic equipment, others might have only recently moved into solar.
It’s not easy to tell the differences simply by looking at a solar panel. The glass and frame is simply the box/packaging surrounding the components which make the real difference. The real quality of a solar panel like an LG panel is reflected inside the solar panels, in the composite of chemically treated glass, chemically treated silicon cells, various plastics, protective films, aluminium, sealants and interconnecting wiring.
Solar panels spend their entire life in the hot sun and cold rain, harsh environment for any material, let alone a composition of different materials bonded together. Under such conditions, materials can – and do – chemically change over time reacting with each other and creating new chemicals and compounds as they age. Their elasticity also changes over their life affecting the stresses and tensions they place on each other. Cheaper panels sometimes use cheaper input materials and may have not been on Australian roofs long enough to see how these materials survive the harsh Australaian Sun.
Solar manufacturers with a strong understanding of materials science who invest heavily in research and development are able to understand and predict how these external conditions are likely to affect the materials. Some, who have been manufacturing consumer goods for many years also, have the benefit of hindsight and learning. Typically, manufacturers who understand these issues will have accreditation to ISO standards for manufacturing and will have advanced quality assurance processes and controls described on their promotional material. True quality assurance is about understanding what causes variation and controlling it through research, not just checking the final product and hoping to identify faults or defects.
LG is one of the manufacturers' of solar panels who has dedicated decades of research into the manufacturing process of our LG panels. LG panels manufacturing video
Installing solar power will add an additional benefit to your property, such as a pool or a modern kitchen can add appeal of your property. Home buyers today are increasingly looking for homes that are energy efficient.
By installing solar power, you can increase the efficiency and appeal of your home, and you will also deliver a degree of certainty to yourself and any future owner in terms of energy costs. And better yet, the Government may pay a chunk of the cost of the solar power system, thanks to available government rebates.
The amount of electricity a solar PV panel can generate is reduced as temperatures increase. A Solar panels' rated output is measured at a temperature of 25°C. The power output slowly decreases as the panel temperature rises.
- Help reduce your electricity bills;
- Enjoy a return on your investment;
- Receive Government rebates – right now!
- Increase the value of your home;
- Any form of renewable energy is good for our future. Help combat global warming by reducing green house gases*
- The solar power that you generate and use is free (after the initial purchase of your system). Ten years from now…it’s still free. Meanwhile,prices for fossil fuels and electricity rise higher and higher year after year.
- No fuel, waste, or pollution is expelled in its usage.
*Solar modules are emission free once manufactured.The energy used for manufacture and transport of LG panels is estimated to take approximately 18 month in Australia to offset the emission before the solar energy created becomes 100% emission free.
Like any manufactured product, not all solar panels are equal. Some use the absolute best materials and equipment to manufacture them and others do not. Some conduct extensive research and development into long term performance and have deep understanding of how the materials will behave and others do not. However, it’s not easy to tell the differences simply by looking at a solar panel, so what can go wrong and how can you tell them apart?
Solar panels are made of a composite of chemically treated glass, chemically treated silicon cells, various plastics, aluminium, sealants and interconnecting wiring. Solar panels spend their entire life in the blazing sun and freezing rain, and incredibly harsh environment for any material, let alone a composition of different ones bonded together. Under such conditions, materials can – and do – chemically change over time reacting with each other and creating new chemicals and compounds as the age. Their elasticity also changes over their life affecting the stresses and tensions they place on each other.
Solar manufacturers with a strong understanding of materials science who invest heavily in research and development are able to understand and predict how these effects are likely to occur. Some, who have been manufacturing solar panels for many years also, have the benefit of hindsight having seen what can go wrong in the real world too.
Typically, manufacturers who understand these issues well will have accreditation to ISO standards for manufacturing and will have advanced quality assurance processes and controls described on their promotional material. True quality assurance is about understanding what causes variation and controlling it, not just checking the final result and hoping to catch mistakes.
Here are some of the commonly seen issues that can occur when materials science is not well understood.
Delamination occurs when the bond between the plastics (on the back) and the glass (on the front) separate. This is catastrophic for a solar panel because it allows air and moisture to creep inside which will cause corrosion and imminent failure. Delamination will occur if:
- Inferior plastics are used or
- If the thermal properties of the plastics are poorly understood so it doesn’t melt to exactly the right point or
- The plastics or the glass or not perfectly clean and compatible or
- The laminating machine is inferior and poorly regulated for pressure and temperature
When you are assessing a solar panel, look very closely for bubbles, creases or imperfections on the plastic rear surface as an indication of the workmanship in lamination. Ask your supplier if they know who supplies the plastics and look for evidence of quality brands.
Sealants are used to seal the junction box on the rear of the solar module to prevent moisture getting into connections and sometimes to bond the laminates solar panel into its aluminium frame. If poorly matched, some sealants can react with the plastics causing premature degradation and although non-flammable sealants are available, cheaper, flammable alternatives are available and are sometimes used to save money.
Frame sealants need to flexible to allow for some thermal expansion and contraction between the glass laminate and the aluminium frame.
When you are assessing a solar panel, look very closely for evidence that the sealants are applied precisely and carefully as a sign of good workmanship. Excess sealant indicates poor control over the dosage and could mean that too much is in some places, and too little in others. Ask your supplier if they know who supplies the sealants and if they are non-flammable.
Silicon solar cells are made of very thin wafers, usually around 0.20mm thick. Although they have some ability to flex, they can and do suffer from stress induced cracks which are so small they are almost impossible to see with the naked eye. These are called micro cracks and can lead to loss of power and potentially failure over time.
Micro cracks can be caused by poor handling of the solar cells during assembly (usually through non automated systems), poorly maintained equipment or transport damage from vibration or shock if improperly packaged. It is not possible to see micro cracks but good manufacturers use Infra-Red scanning cameras which can detect and isolate micro cracked cells during processing and use the feedback to tune their machines better.
When you are assessing a solar panel, look for quality packaging and careful transport by your installer as a sign of good workmanship. Ask your supplier if they know whether the supplier uses Infra-red scanning or other techniques to minimise and control micro cracking.
Yellowing and browning
Similar to the snail trail issue, yellowing or browning is an indication of a poor understanding of materials science and is also typically caused by an uncontrolled chemical reaction between materials causing the (usually) white plastics to turn yellow or brown.
It has also been known to occur on the surface of the cell, in a chemical reaction between the chemicals on the surface of the silicon cell and the chemicals used to treat the glass. Yellowing and browning are almost always something that occurs in the first few years of exposure to sunlight. Fortunately, (historically) performance does not appear to significantly affected due to yellowing or browning however, it is a sign that something uncontrolled is happening.
When you are assessing a solar panel, look very closely and make sure there is absolutely no evidence of yellowing or browning as a sign of good workmanship. Ask your supplier what the manufacturer understands about the issue and how they have addressed the material science to avoid its occurrence.
Inclusions and alignment
When a solar panel is being assembled and prepared for lamination it is crucial that no dirt, blobs of solder, dust, hair or other foreign particles are inadvertently included or they can cause bubbles in the laminate or air gaps which can lead to premature failure. A 100% perfectly clean environment is essential in manufacturing.
The alignment of solar cells is also an important indicator of workmanship in a solar panel. Poorly aligned solar cells are indicative of poor process control and can introduce stress into the interconnections or the potential for current leakage between cells.
When you are assessing a solar panel, look very closely and make sure there are absolutely no inclusions accidentally laminated under the glass and that the solar cells are perfectly aligned as a sign of good workmanship. Ask your supplier whether the manufacturer uses automated or manual assembly methods when they assemble their solar panels.
LID and PID
Potential Induced Degradation (PID) is a relatively recently discovered phenomenon which can occur in solar panels although a concise understanding of what causes it is still missing. Recent tests results presented at a solar conference in 2012 showed that solar panels which are susceptible can lose as much as 30% of their rated power through this effect.
What is known is that sodium enrichment occurs between the chemicals used on the surface of the solar cell and the glass in certain circumstances, causing a leakage of current between the cells and the solar panel frame. The intensity of the degradation depends on the module type, the ambient environmental conditions and the position of the solar panel in the array string. A high system voltage (eg 600V +) and high ambient humidity can lead to a moisture film on the solar panel surface. It is assumed that a drift of positive ions occurs from the glass towards the solar cell in the opposite direction, which is believed to cause degradation in the solar cell.
Light Induced Degradation (LID) is another phenomenon that occurs in solar panels, although it is better understood. All solar cells degrade when they are first exposed to sunlight to some degree, varying depending on both the technology type and some of the chemical characteristics which scientists are still learning about. It is generally accepted that the effect is most pronounced if boron oxygen defects are more prevalent within the silicon structure, although it can occur on the surface layers too. The result is simply described as an increase in the density of the material which makes the movement of electrons more difficult, which results in less power flow.
Thin Film solar panels for example, exhibit relatively higher levels of initial degradation (in the first 30 days) but manufacturers understand this well and over-rate their power to take into account the losses they know will occur.
However, in Monocrystalline and Multcrystalline solar panels, the effect is more subtle (in the order of around 0.5% power loss) and not all manufacturers take it into account or understand it as well. The effect is more pronounced in Monocrystalline panels although Multcrystalline panels with the can also suffer from the effect if the oxygen content of the silicon is particularly low. Some manufactures understand LID well although no standard tests or standards are in place.
When you are assessing a solar panel, ask your supplier whether they have undertaken any PID or LID testing and what if any test results can be provided to demonstrate their knowledge of the issue and what they have done to minimise its effects.
Solar cells within solar panels are interconnected using a flat, conductive ribbon in series and parallel connection. Most use a tin coated copper ribbon although the number of connections, width and thickness varies by manufacturer.
An issue increasingly well understood by quality manufacturers is how these interconnectors are connected (soldered) to the silicon solar cell and how the connection method maximises conductivity without placing undue stress on the solar cell. Poor interconnections can cause micro cracking in the solar cells through thermal expansion and contraction stress or the interconnector can break. In the worst case, a poor solder connection which opens and closes with thermal movement can cause an arc and potentially burn out or combust the plastic backing materials.
For example, some manufacturers solder the entire length of the interconnector, and some only solder every few millimetres, theoretically reducing stress caused by thermal expansion and contraction. Some use thinner interconnectors which can theoretically stretch more, avoiding stress.
When you are assessing a solar panel, observe the neatness, alignment, size and quantity of the interconnectors. Ask your supplier what type of interconnector and soldering method is used to demonstrate their knowledge of the issue and what they have done to minimise its effects.
The vast majority of solar panels are fitted with aluminium frames which provide mounting attachment points and protection for the edges of the glass laminate. Importantly, the expansion and contraction ratio of aluminium and glass are different and hence the materials used to join them together are important to avoid stress build up.
Most manufacturers use butyl rubber or flexible double sided tapes which allow some movement but ensure the glass is retained within the frame. Obviously, the long term adhesion strength and UV stability of these materials is crucial and cost saving measures through the use of inferior materials have demonstrated rapid failure of the bond.
The frame itself can come in various types from double walled and highly rigid, to quite thin walled and relatively flexible. Both serve the same purpose when attached securely to quality mounting systems, although logically a more rigid frame offers less chance of distortion and potentially coming loose over time. In double walled frames, it is important that the cavity between the walls is vented so that ice cannot build up inside and split the frame in cold climates.
Some frames are screwed together and some are joined using push fit mitre joints. When manufactured correctly using tight tolerances they are equally effective.
When you are assessing a solar panel, look very closely and observe the type and integrity of the materials used to bond the frame to the glass laminate. Ask your supplier about the materials used for bonding and if using push fit mitre joints what they do to ensure that tolerances are held in specification.
A seemingly subtle but important feature in the construction of solar panels is the junction box. Attached to the rear of the solar panel, it serves several important functions. Firstly, it seals the rear of the solar panel where the interconnectors exit. As such, it is vital that it is well sealed so that moisture cannot enter the panel. Some are permanently sealed, others can be opened up but either way quality moulding’s and sealing faces are important. Most are made of plastic and some are cast aluminium.
Secondly, it houses connection points for the cables which exit to allow you to connect each solar panel together. These connections need to handle the extremes of weather over decades and handle quite high currents so quality connections are important. It also houses small electronic devices called diodes which protect the solar cells in the case some are partially shaded. Some diodes exhibit higher losses and create higher temperatures than others, leading to potential stress.
Lastly, the majority are filled or partially filled with a sealant to protect the entry to the solar panel and sometimes filled to the brim to fully encapsulate the diodes, connections and cables. The quality and flammability of this sealant is an important factor too.
When you are assessing a solar panel, look very closely and observe the type and integrity of the junction box to ensure it fits well, is perfectly sealed and if operable, that it seals up perfectly when re-closed. Ask your supplier about whether the materials are flammable and look for quality workmanship.
The amount of electricity being generated is directly related to the amount of sunlight shining on to your home solar system. The more your solar modules are covered in shade, the less electricity your system will generate.
Even a single antenna or a chimney shadow on your panels can affect performance and electricity output. Depending where you reside in some areas of Australia such as the Blue Mountains near Sydney over 10% of homes are less suitable for solar due to tree coverage close to the home.
The new technology of micro-inverters on each panel instead of one large string inverter can help with shadow issues as the losses associated with shade can be reduced by as much as 25% with each individual panel being managed to achieve maximum electricity output. Talk to your LG dealer if your shadow issue is a serious one and check if power optimisers or micro-inverters are a potential solution for you.
A solar system can be connected to the grid using a Gross Meter or Net Meter.
Under Gross Meter scheme all the electricity generated by your solar system is exported back to the grid and you are paid for it usually by way of a credit on your electricity bill. The payment you receive for this exported electricity is called the feed-in tariff. Not all electricity retailers pay a feed in tariff. You may need to shop around. The Gross Meter measures the entire output of the system separately to your electricity consumption.
Today most of the solar power electric systems are installed under the Net Meter scheme. A net metering system means your inverter sends the electricity your system generates to the meter box.
If you consume electricity in your house at that point in time the solar system will supply it, therefore this electricity is "free". If the amount of electricity generated by your solar power system is more than you consume at that point in time, the additional electricity is exported back to the grid. Your net electricity meter then measures how much you exported. The payment you receive for this exported electricity is called the feed-in-tariff. At night you import electricity and the net meter measures how much you consumed and adds it to the electricity you consumed during the day from the grid.
The rate of feed-in-tariff you get paid varies from State to State and from energy company to energy company. We suggest you shop around. Your solar power system installer may be able to guide you as to which energy retailer offers the best feed-in-tariff rate. (LG Dealer Search)
The amount of energy in sunlight that a solar PV panel receives over a day is expressed in peak sun hours. As the amount of energy generated by a panel is directly proportional to the amount of energy it receives from sunlight, it is important to install panels so they receive good exposure to direct sunlight.
Your accredited solar system designer/installer will calculate the amount of energy generated by the solar PV panel from the peak sun hours available. This means your installer should be able to tell you how many kW/h your chosen solar system will generate in your particular installation situation. Ask for this estimation in writing before the installation. Peak sun hours vary throughout the year. Try our output calculator.