Although it probably goes without saying, shading is not good for solar panels. A shadow cast on even just part of one solar panel in your solar array can potentially compromise the output of the whole system. What are some strategies for dealing with potential shading of solar arrays?

Why are solar panels averse to shade?

In most instances, solar photovoltaic (PV) systems for homes and businesses consist of solar panels (the collection of which is referred to as the ‘array’) and an inverter. The solar panels catch sunlight and convert it into DC (direct current) electricity, and the inverter in turn converts the DC electricity into grid- and appliance-compatible AC (alternating current) electricity.

Most small-scale solar systems, such as a 1.5 kilowatt (kW) system, for homes and small businesses will include at least 6 panels. However, systems can easily be composed of more panels where necessary, depending on the output of the panels in question and the electricity demands of the occupants of the building they supply power to.

For technical reasons related to the voltage requirements of the system’s inverter, solar arrays are usually divided into ‘strings’ of solar panels. Small systems may only have 1 string, while large systems could have many more. One string could consist of a single panel, but usually they have more.

You can think of a string of panels as something like a piece of pipe, and the solar power is like water flowing through that pipe. In conventional solar panel strings, shade is something that blocks that flow. If, for example, shade from a tree or a chimney is cast on even one of the panels in the string, the output of the entire string will be reduced to virtually zero for as long as the shadow sits there. If there is a separate, unshaded string, however, this string will continue to produce power as per usual.

In extreme cases, a shadow does not necessarily need to fall on an entire panel–depending on the technology used in the solar panel in question, shading of even just one cell could flatten the output of the panel and in turn the entire string. Many modern panels, however, come equipped with devices called bypass diodes which minimise the effects of partial shading by essentially enable electricity to ‘flow around’ the shaded cell or cells.

Strategies and technologies for dealing with shaded solar panels

Although the performance and therefore the return on investment (ROI) from a solar power system can be severely affected by shading–especially shading that occurs regularly due to an object that casts a shadow at the same time every day as the sun passes through the sky–there are a number of ways to avoid or mitigate these effects.

Site your solar panel array where there will be no regular shading

This is the first and most obvious step to making sure your system does not suffer the consequences of being partially shaded. It is extremely important to consider all times of day for all seasons of the year when working out whether some nearby object might cast a shadow onto your roof. You can check this yourself or alternatively your Solar Choice broker will check to ensure there is no shading on your roof using a program called Nearmap.

An example of a tree which has grown tall enough to cast a significant amount of shade on the solar array of a nearby roof.

Solar system owners should also be vigilant in making sure that there are no nearby trees which might grow tall enough to eventually cause shading issues. Solar system lifespans are typically expected to be 25+ years, during which time trees have plenty of time to grow.

Clouds are another source of potential shading. Clouds passing through the sky during the day may also result in fluctuations in system output, but these are basically unavoidable. Amorphous silicon solar cells are said to be better at handling shading than crystalline silicon solar panels, but generally speaking the relatively low overall efficiency of amorphous panels means that crystalline modules are a better choice.

There are some other technologies under development that may offer high efficiencies even in inclement weather, such as ‘super black’ solar cells, but most of these are still either expensive or not yet commercially available.

Use an inverter that has MPP Tracking capability

Maximum Power Point Tracking (MPP Tracking or MPPT) is a technology that now comes standard in most inverters quality inverters. An inverter equipped with an MPP Tracker is able to ‘average out’ the difference between the current and voltage of 2 or more strings of inverters, so that even if the output from one is sub-optimal, the system is still able to take advantage of whatever juice it is creating and add it to the more powerful string, producing a consistent, usable volume of power. Inverters without MPPT capability simply lose the output from the weaker string once it passes below the required output threshold.

An example of partial shading in a conventional multi-string inverter system (Image credit: pvsolarchina.com)

There are also a number of companies (such as SolarEdge) who offer module-level MPP Tracking technology. These inverters offer MPPT for each individual solar panel, averaging the output of all panels more ‘intelligently’ than a central inverter, which can make adjustments only at the string level.

Enecsys is another company that produces a type of mirco-inverter. Enecsys micro-inverters sit on individual modules and converter all power from each panel directly into AC electricity, avoiding power losses from shaded strings. Tindo Solar panels are an Australian-made solar panel brand that come equipped with Enecsys inverters.

© 2012 Solar Choice Pty Ltd

The University of New South Wales’ School of Photovoltaic and Renewable Energy Engineering is in the process of developing building-integrated photovoltaic (BIPV) roofing materials which can also assist in regulating building temperature. The research initiative will be undertaken under the Co-operative Research Centre (CRC) on Low-Carbon Living grant program, which will provide $28 million dollars over 20 years through the Department of Innovation, Industry, Science and Research.

The faculty’s prototype model has already been demonstrated to be capable of consistently producing air as warm as 25 degrees through even the cold months of winter. The technology is to be integrated into roofing panels, to provide the combined, mutually-complementing benefits of thermal comfort control and electricity production. The BIPV roofing panels are to be just one in a series of similar, ‘carbon-positive’ technological developments expected to be developed under the program.

“A lot of people aren’t aware that the biggest opportunity for emissions reductions is in buildings,” said CRC head Professor Deo Prasad, of UNSW’s faculty of the Built Environment. “The built environment is responsible for 40 per cent of energy use and Australia’s homes account for 16.5 per cent of our emissions in electricity use alone, without accounting for energy embodied during the production and disposal of building materials. Unless we have carbon-positive products, it will be difficult to have carbon-positive buildings.”

The CRC Program Leader for Integrated Building Systems Associate Professor Alistair Sproul, is in the process of developing a thermally-driven air-conditioner, in the same vein as the thermal roof BIPV. “The idea is that instead of simply putting solar cells on top of regular roofs, they are integrated, so that the minute the metal roofing is installed, it starts to pay back its carbon debt by pumping power into the grid and providing warm air in the winter,” he said.

Source: UNSW School of Photovoltaic and Renewable Energy Engineering

© 2012 Solar Choice Pty Ltd

(Top image: Prof Deo Prasad and Assistant Professor Alistair Sproul of UNSW. Image via UNSW School of Photovoltaic and Renewable Energy Engineering)

The University of Wollongong has installed a building-integrated photovoltaic (BIPV) system on the roof of its McKinnon Pavillion. The installation is part of the University’s ‘McKinnon Precinct Landscape Masterplan’, which also includes rain-gardens and a 500,000L in-ground rainwater tank.

The BIPV system is composed of 44 Uni-Solar PowerBond PVL PV laminate panels, made of flexible, thin-film silicon to allow the array to match the waveform structure of the roof (below). The thin-film cells were chosen both for their flexible nature as well as their relatively good performance to hot, sunny conditions. Panels adhere to directly the substrate of the roof in a way similar to contact paper.

The 5.89kW system is expected to produce up to 20kWh of electricity per day, which will be fed into a nearby building, where it will help to offset electricity consumption.

The free-standing roof has become a key feature of the Precinct, and in addition to producing electricity, also acts as a shelter for students sitting underneath. It also plays a role in channeling water into the Precinct’s rain gardens.

University of Wollongong McKinnon Pavillion solar BIPV installation (Image via University of Wollongong).

 © 2012 Solar Choice Pty Ltd

All images via University of Wollongong

Resources and links:

University of Wollongong News & Media, “Sustainability theme in sculptural roof design”

University of Wollongong News & Media, “Greening McKinnon set for Stage 2“

Dyesol is positioning itself to revolutionise the solar photovoltaics (PV) industry by making available an innovative but still largely uncommercialised PV technology: the Dye Solar Cell (DSC). DSC is a 3rd generation solar PV technology that uses a ‘sandwich’ of materials to mimic the photosynthetic process of plants in order to create electricity from sunlight. It has numerous applications, including Building-Integrated Photovoltaics (BIPV) and portable PV.

Non silicon-based solar power?

Silicon PV cell structure and the photovoltaic effect. (Image: Creative Commons via Wikipedia.)

Conventional solar PV

Although dominated by conventional silicon-based solar panels, there are also a number of non-silicon solar PV technologies (usually used in thin-film PV) available on the market, but most function in a way similar to silicon-based modules: light strikes a semiconductor substrate with contains a positive-negative (p-n) junction, and electrons are jostled into moving through it, then flowing into an electroconductive material (such as aluminium) to produce harnessable DC electricity.

DSC Solar Cell Technology Diagram (Image Via Dyesol)

Dyesol’s Dye-based solar PV

DSC technology, on the other hand, in the place of a dense film or substrate semiconductor, incorporates a triple layer of nano-particulate titania (Titanium Dioxide, used as a pigment in paints and, rather oddly, toothpaste), a long-life dye, and an electrolyte. The first layer is a nanotechnology material, while the latter two work to emulate the natural photosynthetic process that occurs in the leaves of plants. The end result is that sunlight is converted into electricity as opposed to being trapped in sugars, as happens in plants. The ‘bread’ of Dyesol’s material sandwich takes the form of two electroconductive materials–one transparent on the light-facing surface, and another acting as a substrate behind the cell. These lead the electricity out of the cell to whatever its end use may be.

Key Advantages of Dyesol solar PV technologies

-Simpler production processes mean lower cost than conventional silicon-based PV technologies, as well as lower embodied energy in manufacture

-Can be applied like a film to the surface of a number of different substrates, including conventional building materials

-Can replace conventional glass panels and windows in buildings instead of taking up roof space

-Can be produced in a variety of different colours, for flexibility in building design

-Produces electricity even in low-light, real world conditions including cloudy and hazy days, dappled lights, dawn and dusk

-Avoids the use of expensive raw materials and has no toxic emissions

-In 2008 saw peak conversion efficiencies of up to 11% (sunlight to electricity) in laboratory conditions (comparable or greater than peak efficiencies for many other thin-film solar PV materials)

To whom are Dyesol materials and technology available?

Dyesol’s DSC materials are available for purchase in the Dyesol online shop for academics and others learning about the technology. Concurrently, Dyesol is working with key multinational companies to bring DSC integrated products to the mass market in a variety of applications, including in steel roofing and glass windows. Projects are currently underway with Tata Steel, one of the world’s largest steel producers and with Pilkington North America, one of the world’s largest glass makers. Dyesol is a truly global company with headquarters, laboratory and engineering facilities in Queanbeyan, NSW (recently visited by Australian PM Julia Gillard) and operations in Italy, the UK, Japan, and South Korea, among other countries.

Dyesol’s bold vision: grid price parity in the UK

At least for the near-term future, it seems that conventional solar PV modules are likely to remain the most readily available and cost-effective option for roof-top retrofit residential solar installations. Meanwhile, however, Dysol is pushing the envelope in its efforts to commercialise DSC, and in a joint demonstration project with Tata Steel in the UK, has made an explicit goal of ensuring that the electricity produced by its modules is competitive with that produced by the electrical grid, thereby eliminating reliance on the UK’s feed-in tariff for economic viability.

This is an impressive goal, especially considering that most solar PV installation companies in the UK are trying to come to grips with the recent, premature slashing of these very government incentives–many forecasting a kind of solar Armageddon. Should Dyesol achieve its goal, there will likely be repercussions for the entire solar PV industry. As the whole point of subsidisation of renewables is to enable competitiveness with fossil fuel generation, solar electricity at grid prices could completely transform the way that solar PV is seen as a renewable energy source, and possibly even shape the future trajectory of subsidisation for solar PV–doubtless much to the ire of Dyesol’s competitors.

© 2011 Solar Choice Pty Ltd

Solarwatt is a solar photovoltaic (solar PV) module maker based in Dresden, Germany. In addition to standard solar modules, the company also provides off-grid solar and building-integrated photovoltaics (BIPV) solutions.

What are the advantages of building-integrated photovoltaics?

Solarwatt BIPV Easy-In Roofing solar panels on a commercial building in Germany. (Photo via Solarwatt.)

BIPV is a fast-growing section of the solar photovoltaics (PV) industry in both Australia and around the world. In addition to the power generation benefits that standard solar PV arrays afford those who install them, high-quality BIPV installations also improve the overall energy efficiency of a building, and the associated cost savings.

Although initially more expensive than ordinary roof-mounted solar panel arrays, for those who were considering installing solar anyhow, BIPV modules can reduce construction and renovation costs; BIPV acts as a seamless substitute for conventional building materials, as well as cutting down on the labour costs associated with solar system installation and roof construction/replacement. More benefits may be found in a well-designed BIPV component’s potential to reduce a building’s operational costs by acting as a form of insulation. For all these reasons, when considering going solar in the context of the entire working lifespan of a building, BIPV can be an attractive option and a good investment for your home.

Solarwatt Easy-In BIPV modules

Solarwatt BIPV Easy-In Solar Panels (black) blend seamlessly into a standard roof. (Photo via Solarwatt.)

Solarwatt’s Easy-In modules are high-performance monocrystalline solar panels (up to 19% efficiency using the most tried-and-tested solar PV technology commercial available) that also serve as a weather-proof roofing material. Installation is simple and intuitive–they attach directly to roof battens, slot together with tongue-and-groove joints, and no additional mounting system is required. A passive ventilation system behind the panels means that heat build-up is minimised, allowing for better performance than conventional frame-mounted panels. Easy-In modules are available with either natural-coloured aluminium or sleek, all-black frames (top image).

Interested in BIPV? Although Solarwatt Easy-In modules are not yet available in Australia, other BIPV solutions are. Request a Solar Quote Comparison by filling out the form to the right of the screen. Solar Choice provides free, impartial advice and comparisons of solar PV system prices, components, and installers Australia-wide.

Resources and links:

Solarwatt Website (All images via Solarwatt)

Solar Choice now has its own electric vehicle–the first of its kind ordered and purchased in Australia. The Mitsubishi i MiEV (“Mitsubishi Innovative Electric Vehicle”), will be parked and charging its batteries in the evening in Manly, NSW when it is not being used on official Solar Choice business. Those living in Sydney will be able to see Solar Choice’s new wheels cruising around the city. In addition to being CO2 emissions-free, the i MiEV is also noise-free: Although its decals and odd shape make it hard to miss when it drives past on the street, the vehicle makes virtually no sound while in operation, proving disconcerting for driver and pedestrians alike.

The first 100% Electric Vehicle in Australia produced for the mass market

Solar Choice Mitsubishi i Miev

The above claim to having ‘Australia’s first 100% electric vehicle’ does come with some qualification: Solar Choice’s i MiEV is the first volume-produced Electric Vehicle (EV) ordered and sold on Australian soil. Although other models of EVs (such as the high-end Tesla roadster) have already arrived in Australia, the i MiEV is the first EV on the Australian market that has been mass produced and is relatively affordable. At around $50k AUD, it isn’t as cost-competitive as a many cars on the market (although the price will doubtless come down as EVs become more common), but the car offers significant savings on the cost of fuel. i-MiEV owners will save hundreds or thousands of dollars in petrol per year, as the vehicle can be charged overnight on off-peak rates of 6c/kWh, totalling less than $1, on which the vehicle can be driven for up to 160km.

Features of the Mitsubishi i-MiEV

Solar Choice EV at Ocean Care Day 2011 in Manly, NSW. (Photo credit: Robynne Millward of Manly Environment Centre.)

The i MiEV has a number of features that make it innovative and allow it to be emissions-free while driving. The most vaunted of these features are the following:

-High-capacity, high-energy density litium-ion batteries means versatility in fuel sources. Having batteries instead of a fuel tank means that electricity is drawn from the electrical grid. In Australia, this of course means that power is ultimately sourced from fossil fuels (i.e. coal), but even taking this into account, the i MiEV only produces 30% of the emissions of a standard petrol-powered car of the same size. What’s more the electricity that charges its batteries need not necessarily come from the grid–if the car is charged using only a solar car port, or during the day at a home with large solar power array, for instance, then the electricity powering the car will be totally CO2 emissions-free.

Mitsubishi i MiEV electric vehicle charging station. (Image from http://global.ev-life.com/.)

-A 3-way battery charging system: two slow-charge modes (100V and 200V, 7-14 hours charge time) which can be accessed via any conventional home or car park power point, and one fast-charge mode which can have the ‘tank’ 80% full in 30 minutes using a specialised EV charger not yet widely available in Australia.

-Unusual chassis layout: The i MiEV is the 100% electricity-powered version of the Mitsubishi i, the company’s innovative and popular ‘minicar’ with an unusual ‘rear-midship’ design–its engine sits underneath the rear seat of the car, as opposed to in the front under the bonnet. This feature of the i’s design made it ideal for the placement of the batteries required to power the EV version’s electric engine. The fact that the i MiEV’s engine is powered by its battery as opposed to petrol allows it to be much smaller than it would be with otherwise–conveniently leaving room for all the parts that cannot be found in conventional automobiles–an inverter, a charger, and the battery bank.

-A small, high-efficiency motor that takes up much less space–and provides more torque–than a petrol-fired engine of comparable size. The i MiEV has surprisingly good pick-up for car with such a small engine!

A dial above the spedometer on the i MiEV's dashboard indicates when the car is using deceleration power to charge the engine. (Image from http://global.ev-life.com/.)

-Regenerative charging: The i MiEV’s re-channels the power produced in rolling downhill and braking to charge the car’s battery. The energy produced during long descents, for instance, can be seen on a ‘power meter’ on the car’s dashboard.

Are Electric Vehicles the future of personal transportation?

Solar Choice’s EV may be one of the first of its kind on the road in Australia, but as production capacity and demand for similar vehicles increases globally, they will undoubtedly cease to garner much attention. Much like the Toyota Prius petrol-electric hybrid went from head-turner to commonplace since its introduction in 1997, emission-free cars like the i MiEV, in an ideal world, will become a common sight. In fact, Chevrolet/Holden, Ford, and Nissan, plus a handful of other companies all have EV models in their product lines.

City of Sydney Solar Powered Electric Car (Photo: Minnie Bye)

In addition to replacing fossil fuel-based automobiles from the road, EVs could potentially revolutionise the way that electricity is stored and distributed in the grid, and make the relatively erratic nature of renewable energy production harnessable–if there were thousands or millions of EVs in operation in a nation, resting cars’ batteries could be used as a repository for electricity produced from solar power systems, and owners could be paid for the electricity drawn from their cars’ batteries into the grid at peak demand times. Technology like this is still a long way off, and will require a fair amount of forward-planning by governments and/or private grid owners–so let’s not hold our breath. Some private enterprises are already looking into ways to make this vision a reality: as we have written previously, developing grid infrastructure to accommodate renewables is one of the aims of companies like Better Place.

The Solar Choice team around the new i MiEV electric vehicle

Written by James Martin

Solar Choice Analyst

© 2011 Solar Choice Pty Ltd

Resources and Links:

Mitsubishi’s i MiEV portal page

See the article about Solar Choice’s new ride in the Manly Daily.

Related Solar Choice blog articles: Ford and Sunpower team up for Solar EV charging stations, Better Place: Electric Vehicle Charging Stations : Solar-Powered Carports

SMA Sunny Boy 2100TL inverters, part of SMA’s transformerless inverter range, are now available in Australia. The vast majority of the solar installers in the Solar Choice installer network offer SMA products as a primary or standard option in their installations, and the addition of the 200TL will allow increased flexibility and options in system design. What are the features and specs of the SMA Sunny Boy 2100TL?

SMA Sunny Boy 2100TL transformerless inverters for 2kW solar systems

With a maximum input wattage of 2200W (Watt, or 2.2 kilowatt (kW)), the Sunny Boy 2100TL is a great option for those who are looking to install a 2kW solar panel array with all the benefits of a transformerless inverter. What are the features of the features of the Sunny Boy 2100TL?

Benefits of 2100TL solar inverters

-Peak (maximum) efficiency of 96%–ranked highest efficiency and most competitive among solar inverters in the 2.0-2.1kW power class. This higher efficiency means faster payback periods on your solar system.

-Designed and developed in Germany especially for the Australian market in response to demand for small residential solar power systems across the country.

-Broad input voltage range–between 125 and 600V, offering more flexibility in solar panel arrangement. The input voltage is the voltage that comes out of your solar panel array. Your array’s output voltage will vary depending on the arrangement of ‘strings’ of panels in the array.

-Optional communication interfaces (wireless or via cables), so that you can monitor the performance of your system and identify and deal with issues quickly.

-Flexibility in choice of solar panels and system size.

-Sunclix DC connection system for easy, safe installation. Using Sunclix also means that fewer cables required in each installation.

-Lightweight and easy to install.

Is the Sunny Boy 2100TL right for you? Contact a Solar Choice Solar Energy Broker to discuss your needs and options–we have a network of installers across Australia who offer a range of components for solar power systems. Solar Choice offers impartial advice on solar power systems, at no cost to the customer. 

Written by James Martin

Solar Choice Analyst

© 2011 Solar Choice Pty Ltd

Sources and Links:

SMA Australia

Previous related Solar Choice blog entries: Transformerless vs conventional inverters - Sunny Boy visits Solar Choice

The world record for solar panel efficiency goes to SunPower‘s solar panels: 24% cell efficiency (sunlight  –> usable electricity in laboratory conditions) and 19.6% conversion efficiency (sunlight –> usable electricity in real-life conditions) with the SunPower E19 / 320W solar modules. SunPower prides itself in its hard-earned reputation for world-leading technology and excellent customer service. SunPower panels are commonly used in residential solar, building-integrated photovoltaics (BIPV), commercial solar, and utility-scale solar installations.

(Interested in finding out more about SunPower solar modules? Get a free comparison of solar quotes from installers in your area, anywhere in Australia and talk to one of our brokers about whether SunPower is the best option for you.)

SunPower Solar Panels: World-leading 19-20% efficiency

-SunPower monocrystalline solar panels: E19 and E20 series-

Monocrystalline solar cells have a reputation as the most efficient kind of solar photovoltaic (PV) cell, and the first query from many Solar Choice and Solar Selections customers is, “Are monocrystalline solar panels better than polycrystalline solar panels?” In the Solar Choice blog we have previously discussed the issue of efficiency and solar technology, and pointed out that more important than efficiency or technology type is the quality of the brand of solar PV panel in question. The question of durability, quality, and the credibility of the manufacturer trump nominal efficiency every time. (Solar Selections also has an excellent article about the importance of efficiency in choosing your solar panels.) The technology utilised in SunPower’s monocrystalline solar panels does indeed enable high efficiencies, but that doesn’t necessarily mean that all monocrystalline panels can reach such high efficiencies–in fact, the average is more in the range of 14-16%.

E19 and E20 are SunPower’s signature lines of solar panels use monocrystalline silicon technology. Their names stand for their nominal efficiencies–19% and 20%, respectively. These numbers are the highest that can be found on the solar panel market, and it is only with care and precision in design and engineering that SunPower was able to achieve these impressive figures. The company takes pride in its accomplishments, and has a reputation that is hard-won and well-earned.

-SunPower E19 and E20: Key Attributes and Points of Difference-

-SunPower E19 and E20 lines for solar and residential solar power-

SunPower E19 series - Industry-leading 19% efficiency

SunPower’s E19 series solar panels 238 watt (W), 72-cell panels, while the E20 series is available in either a 327-W, 72-cell panel, or a 333W, 96-cell panel. The 72-cell panels are generally used in residential solar applications, while the 96-cell panels are more likely to be used in large-scale commercial applications.

-As noted above, SunPower panels have the highest efficiencies of any solar photovoltaic panels on the market. This means up to 50% more power per unit area than you would expect to get from conventional designs. This in turn means reduced installation costs because fewer panels are required to get the same amount of power.

-Dependable, sturdy design means you can count on your panels continuing to operate over the years through all types of weather. Tempered front glass over the PV cells and an anodised alloy frame mean that the units will be slow to corrode or degrade.

-Transformerless inverter compatibility means that SunPower panels can be used with the solar inverters with the highest efficiency: A winning combination.

-Positive Power Tolerance of +5% for E20 modules: Some solar panels have a power tolerance of +3%/-3%, which means that the panels you install may actually have a lower output than their nameplate capacity. With SunPower’s E20 series, the nominal capacity is guaranteed to be met or exceeded. (E19 panels have a tolerance of +5%/-3%.)

-10 year limited product warranty, 25 year limited performance warranty.

-Product Specifications/Electrical Characteristics-

SunPower E20 series solar panel datasheet (pdf)

SunPower E19 318W solar panel datasheet (pdf)

SunPower E19 238W solar panel datasheet (pdf)

You can see how SunPower panels compare to a number of other name brand panels on the Desert Knowledge Australia website, an invaluable resource for those shopping around for solar panels.

-SunPower Technology: What is Maxeon cell technology?-

SunPower Maxeon solar cell technology. Unlike conventional cells (which use busbars), electricity is collected at the rear of each cell, thereby maximising surface area for sunlight collection.

Maxeon is SunPower’s patented solar cell technology that enables the company’s reputation for world-leading efficiency. Most crystalline solar cell technologies have metal busbars–strips of electronically conductive material–that sit on the face of each solar cell. Instead of having such busbars, electricity generated when SunPower panels capture photons from the sun is transferred to a conductive plate at the rear of each cell. This means that more of each cell’s surface area is used in the capture of sunlight, which in turn means higher efficiency.

Another feature which has enabled SunPower to make the headway that it has with its panel efficiency is the way that individual cells are shaped. They can be tiled closely within the solar module frames, which means a greater number in a smaller area. SunPower panels also employ an anti-reflective glass which helps to trap in sunlight and maximise power output.

-Other Information about SunPower Panels-

-Other products by SunPower-

SunPower also has an E18 series panel, which has efficiencies of around 18%.

Ford Motor Co and SunPower recently formed a strategic partnership to offer photovoltaic carport charging stations for electric vehicles.

-Component standards met/awards-

-All E19 series SunPower solar panels are certified by the Clean Energy Council (CEC) of Australia, and are on the list of CEC-approved components

-PV Cycle– SunPower participates in PV Cycle’s voluntary take-back PV recycling program

-CE mark– SunPower panels are compliant with European Union regulations

-TUV Certification means that claims made by SunPower about their solar panel specs have been independently verified by TUVRhineland

-Warranty-

25 year solar cell performance warranty

10 year workmanship warranty

(Your installer may also offer additional warranties for the entire system.)

Read about solar panel and solar system warranties.

-About SunPower-

-Company Headquarters-

Global Head Office: San Jose, California, USA

Australian Head Office: Belmont, Western Australia

-Factory locations-

Malaysia and the Phillipines

-History in the Solar Industry-

SunPower is one of the oldest players in the solar power industry, starting around 25 years ago. Founder Dr Richard Swanson first conceived of the company during the 1970s oil crisis. Later, in the mid-1980s, when a professor of electrical engineering at Stanford University, SunPower was incorporated after Swanson won grants from the US Department of Energy to research solar power and secured financial backing from venture capitalists. By the mid-1990s, SunPower had installed 10 megawatts of capacity in various locations through the US and Europe. SunPower panels can now be found around the world.

Written by James Martin

Solar Energy Analyst for Solar Choice

© 2011 Solar Choice Pty Ltd

Sources and links:

SunPower Australia Homepage (Images and brochures from here)

Previous related Solar Choice articles: SunPower and Ford form strategic partnership: Electric Vehicles and Solar-Powered Car Ports - Solar Panels and Solar Modules - Questions to ask when considering buying a solar power system - Which solar panels are right for you? - Building-Integrated Photovoltaics (BIPV) - Desert Knowledge Solar Centre solar panel comparisons - Solar Panel Tilt and Orientation in Australia

Nev and Linda Sweeney have been living on their 500-square-meter suburban plot in Sydney’s St Clair Suburb since the early 1980s, and have been trying to live sustainably using the resources on their land for almost just as long. Their approach includes innovative energy generation and efficiency strategies (including off-grid as well as grid-connected solar panel arrays), a permaculture-style integrated food production system, and an army of low- or zero- energy input cooking devices including at least 2 different types of solar ovens.

I visited the Sweeney’s residence for Sustainable House Day 2011 ostensibly as a volunteer, although,  due to the irregular flow of visitors throughout the day, I felt more like a guest. Through talking to them and seeing their home in action, I gained an understanding of some of the challenges and successes that they have experienced  in their drive to transition to self-reliance over the past 3 decades. Their adventure has required a lot of innovation, experimentation, and trial-and-error, but the home has through this process reached its own equilibrium of inputs and outputs, and the couple has become something of a model for how sustainability can work in practice on a suburban plot.

Chokoes are vigorously-growing vine fruits that taste like cucumbers but have the texture of carrots. They grow like mad over the Sweeneys' orange tree.

Harnessing the power of the sun: solar panels and solar cookers

The property is a showcase of innovations related to resource flow–most notably the Sweeney’s impressively well-integrated food production system which produces, among broad beans, eggs and many other edibles, 40 to 50 kilograms of chokoes per year. The most interesting aspects of the home for the purposes of this article, however, are the parts that utilise the power of the sun to reduce the home’s energy use–solar panels and solar cookers.

Solar Panel Arrays: Off-grid solar and Grid-connected solar

The Sweeneys' 1kW grid-connected solar array, visible on their roof above their fruit trees in the back yard.

Nev and Linda have probably one of the only homes in Sydney that has both a grid-connected solar array as well as an off-grid array. The older of the two is the off-grid system, which Nev installed to power only certain appliances in the home–most notably a number of re-wired lights that run directly off the DC electricity produced by photovoltaics (PV) array and its associated battery bank (which has now been replaced twice). It began 25 years ago when Nev installed a round-celled BP Solarex solar panel and the first set of batteries. The next addition to the system came 17 years ago when Nev added another panel to the array, and the last addition when Nev inherited 4 x 80W panels from his brother. The overall output isn’t easily quantifiable in watts, but the voltage of the array is 12V, which is enough to keep the battery bank charged and operating. The batteries supply a good part of the electrical needs of the house.

The Sweeneys' off-grid solar system, located on garage roof. The batteries and inverter are kept in the garage.

In addition to Nev’s hand-assembled array, the roof of the house is also home to a professionally-installed 1kW grid-connected solar power array. This array was installed on the roof of the house when Australia’s solar power incentives were at the height of the frenzy–a high ($40) REC/STC price from the federal government and a 60c/kWh gross solar feed-in tariff from the NSW government under the now defunct Solar Bonus Scheme. Although the Sweeneys saw little actual need for the array, especially with one of their own already up and functioning, the decision to have the panels installed was a financially obvious one, and the up-front cost was relatively insubstantial for the returns they can expect from it over the life of its operation.

Cooking with the sun: Solar ovens and more

Cooking a lamb roast in one of the solar ovens in the Sweeney's back yard. It needs to be rotated to point towards the sun, but can work even on cool days.

In addition to using the sun to generate electricity, the Sweeneys also use solar energy to cook their food. On Sustainable house day, their yard was full of different models of home-made solar cookers, one of which was quite impressively in the process of preparing a lamb roast for

'No-tech' Solar power oven, made out of cardboard, aluminium foil, and other household materials.

dinner. The oven works even on cold days, albeit slightly more slowly than on hot ones. There are about five different ovens and other cooking and food-drying devices that Nev and Linda have assembled and use regularly in preparing their meals. For those interested in assembling their own solar ovens, you can learn more on SolarCooking.org.

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Are you a New South Wales resident interested in going solar to offset your electricity bills? Solar Choice offers free, impartial advice and Solar Quote Comparisons: Our goal is to help you find the system that best suits your needs. 

Want to know more about Solar Power in New South Wales first? The following articles might be of interest to you:

- 30c/kWh Feed-in Tariff offered to NSW customers through a Solar Choice Network Installers

- Is solar right for you in NSW?

- Solar Power reaching grid price parity in parts of NSW

Written by James Martin