The Details

Attention to Details

Like with almost everything it is the small details that can make all the difference in the long run.

• We use a mounting rack with cable channel to safely store wires (rather than just tucking them under the array to hide them from sight)
• If you wish we can, at no extra cost to you, fit a proven anti-theft mechanism to keep the modules secured in order to protect your investment. The device is as simple as it is clever. Solar panels are fitted to the mounting rack with bolts that use Allen keys to fasten them. After the system is installed a precisely sized steel ball is hammered into the slot, making it impossible to open the screw. A very effective anti-theft mechanism! The only way to open the screw later is to cut a groove into the steel ball with an angle grinder. No thief would want to make that much noise.
• Stainless steel screws are used to fix all components, not just the ones immediately visible to substantially reduce the risk of corrosion. This includes especially the screws holding the mounting rack to your roof beams.
• Inverters installed by us are adjusted to exactly match Western Power specifications, ensuring minimum downtime and maximum output.

Shopping around? Important questions to ask

Once you know that a photovoltaic system is the right choice for you, a decision needs to be made on which components to use and which installer to choose.

Even though you might be out of pocket less than $4000 after rebates, the whole project is worth closer to $13000. Of course you want to be sure that such a big investment is a good one.

Questions you should keep in mind when you talk to different suppliers:

• Who do you get to talk to: a sales rep or a qualified, BCSE accredited, systems designer?
• What qualifications does the designer have? Is he accredited just for Grid Connect or also for Stand Alone Power Supplies (SPS). Dual accreditation ensures that all important details have been learned and applied in various contexts over an extended time, not just heard once in a short crash course.
• Who will do the install? Will the BCSE accredited person be on site for the whole installation, ensuring all standards are met in practice and not just on paper, or will that person just sign the paperwork?
• Quality of components? How reputable are the manufacturers? How long have they been around? How long and comprehensive are the warranties? Especially if the manufacturer is a small player, it pays to ask who imports those components? A major wholesaler can back up warranties in case the manufacturer is hard to track down.
• Quality and sizes of wiring? Cable losses are easily avoidable by choosing cable sizes generously. Double insulated single strand DC cables are recommended by the Australian Standards to increase safety, but they cost more. What does your installer use?
• Shading and positioning? Only a proper shading assessment and positioning of the array in the best available orientation will get you maximum power output from your system. This should be the most important parameter, not the wish to minimise the length of cabling. How carefully is that considered?
• How much attention to details and your individual needs does the installer pay?

Shop around. Ask questions. Then make an informed decision.

Technical Details of our Components

Sunpower Solar Modules

For example the following Watts/Areas:		1000 W need	or	50 m2 area can host
Sunpower high efficiency monocrystalline modules		5.6 m2		8500 W
Most other monocrystalline modules		7.9 m2		6300 W
Thin film (i.e. amorphous silicon)		16.2 m2		3100 W

• Additional PV panels, once the rebate conditions change or feed in tariffs get introduced
• A solar hot water heater
• A pool heater
• Skylights to channel natural light into your house

Those high efficiencies are in part a result of Sunpower's unique 'back contact' technology, where all electrical connections are made on the back side of the solar cells, to maximise the area that collects energy from the sun. The difference is easily seen when you look at a module. The cells are uniformly black, not 'stripy' like others, giving them an aesthetically pleasing appearance.

If your grid connect system will be installed in a prominent position you can further enhance the looks by choosing the all black modules, where even the gaps between the cells are tinted to match, giving the whole module a very uniform colour. The all black modules are only slightly less efficient, delivering 205W each (compared to 210W for the regular modules).

SMA Inverters

SMA is the world market leader for grid connect inverters, for a good reason: their products are designed with reliability, efficiency and ease of use in mind, an excellent example of German quality engineering. They have over 25 years of experience in delivering solutions that connect renewable energy to the grid.

The SMA Sunny Boy series of inverters covers the whole range of grid connect systems, from the relatively small ones that are common here in Australia given the current government rebates, to big ones that will use multiple inverters in parallel.

The SMA Sunny Boy 1100, the inverter specified for our recommended system, is designed for a maximum AC output of 1100W. It comes with a comprehensive 5 year manufacturers warranty, which can be extended to 10 years. And best of all, it is rated IP65, which means it can be installed outdoors. Installing an inverter in a shaded spot outdoors can have several advantages:

• any heat given off by the inverter wont heat up the inside of your house any further on a hot summer day.
• inverters can make a low level humming noise, so you would not want them in indoors areas that otherwise are absolutely silent.
• the inverter can be placed close to the solar array, to minimize the length of cables and therefore cable losses.

Schletter and Conergy Mounting Rack

Mounting profile with cable channel	Brackets holding modules Hook for tiled roof (center)	Stainless steel bolts nuts and washers

Module Performance

Factors influencing the output of a PV system

• Size of the array: the more area is covered with PV, the higher the output.
• Type of module: different module technologies have substantially different efficiencies, ranging from as low as 7% for some thin film modules to over 18% for the most efficient monocrystalline modules.

• Location: in general, the more sunshine a place has on average and the closer this location is to the equator, the higher the output of a PV array. Those two factors are hard to optimise as places very close to the equator tend to have increased cloud coverage. Perth actually is one of the best spots in the world, thanks to its abundant sunshine.
• Orientation: an array will produce most power if it faces the sun at midday. In Australia that means an array should face North. The inclination should be slightly lower than the latitude. In Perth the typical roof slopes of 20 to 30 degrees are nearly perfect.

Efficiency losses in a PV system

• Inverter Performance: different inverters will achieve different efficiencies. But even the same inverter can run at a low efficiency if it
  • gets hot because it is placed in direct sunlight or a poorly ventilated area or
  • is oversized and therefore frequently runs at very low loads (30% of its rated maximum or less).
  An inverter should be sized correctly and its location ought to be chosen carefully.
• Cables, length and size: longer cables will cause higher cable losses. This can be compensated (at a cost) by increasing the cable diameter. In general: the shorter and thicker the cable runs between PV panels and inverter and between the inverter and the switchboard, the lower the losses.
• Shading: all solar panels will have a substantially reduced output if they are affected by shade. This effect will be worst if panels get shaded close to midday, when the sun is the most powerful and panel output should approach the maximum. A careful shading assessment will indicate the the best place for your array.
• Temperature: the hotter solar panels get the lower their power output (assuming the same amount of sunlight). This effect is significant, an extremely hot summer day might produce less power (at least per hour of sunshine) than a cold but sunny winter day. Temperature performance can be optimized by choosing panels that perform well in this respect. Amongst monocrystalline panels SunPower have a particularly good temperature performance. A second aspect is ventilation: by using a mounting rack that allows maximum airflow underneath the modules, we can make use of the cooling effect of the sea breeze, especially in locations close to the coast.
• Module degradation: solar modules can lose some of their performance over time. These losses are very small, usually less than 0.5% per year. SunPower modules for example have a warranty on module output that guarantees 80% of the initial output after 25 years. For the details of that warranty see here. Another potential reason of module degradation can be a buildup of dirt on the module surface. In places with clean air (like Perth) the occasional rain shower will usually do all the cleaning that is required.

Types of PV Modules

Currently three main types of photovoltaic modules dominate the market:

Monocrystalline

The word means that the cells in those modules are made from a single crystal of silicon. The surface of monocrystalline cells has a very even colour. SunPower cells have all their wiring on the back, that is one reason for their outstanding efficiency and also increases the aesthetic appeal. Cells from other manufacturers have part of the wiring in the front, giving them a grid like appearance.

SunPower Cell	Regular Mono Cell

One more technological advantage of SunPower cells becomes clear in this comparison: they are nearly black in colour. That is a result of their ability to absorb most frequencies of light to turn them into electricity. The more a cell deviates from 'black' the more light is reflected instead.

Polycrystalline

The silicon used for polycrystalline cells is cast into a mould rather than grown as a single crystal. As a result multiple smaller crystals form that give the cell a 'galvanised' appearance. The electrical properties of those multiple crystals are usually not quite as good as those of the single crystal used in monocrystalline cells, resulting in lower overall cell efficiency. Efficiencies are still good enough to consider these cells, but mainly when they offer significant cost advantages.

Thin Film

Thin film modules are not made from silicon crystals. They are manufactured in a completely different way, by evaporating materials (sometimes silicon, but also some others) and condensing them into very thin layers onto a glass substrate. Cells using this technology are cheaper to produce and use less refined silicon which, despite the abundant supply of base materials (silica sands), has been in a shortage in last few years.

The big disadvantage of thin film modules available today in Australia is their much lower overall efficiency. To achieve the same output, a much bigger area needs to be covered. That drives up costs for mounting racks and labour. There is little reason to use this technology on Australian roofs. It is best suited to big green field installations where space is abundant and the labour component gets very much automated.

Energy payback time?

Some malicious rumours claim that solar cells require more energy during their production than they can ever generate. That is complete nonsense. A recent study by the IEA (International Energy Agency) compared 41 major cities in 26 countries. Perth took the overall lead with a record low energy payback time of just 1.59 years for roof mounted systems. That figure includes solar panels and all other components (cables, inverter, mounting rack). This study assumes a 30 year lifetime for a PV system, which is used to calculate that the energy required to produce it will be returned 17.9 times over during the system life.

Original Source: IEA PVPS Task 10 report: "Compared assessment of selected environmental indicators of photovoltaic electricity in OECD cities", page 50, download link for the full report here. Reproduced with permission. Click image to enlarge.

Not only is Perth one of the sunniest places in the OECD, Australia including WA also has some of the highest CO2 intensity in the electricity generated here. As a result the CO2 mitigation that can be achieved by a grid connect system in Perth is estimated as over 40 tonnes for each kW of roof mounted photovoltaics (42 tonnes for each of our recommended 1050W systems).

Original Source: IEA PVPS Task 10 report: "Compared assessment of selected environmental indicators of photovoltaic electricity in OECD cities", page 54, download link for the full report here. Reproduced with permission. Click image to enlarge.

Facts and Myths

What happens during power outages?

A grid connect system is not a UPS (uninterruptible power supply). When the grid fails for any reason your inverter will turn the solar system off and disconnects from the grid. This is done for safety reasons. You would not want to feed energy back into a grid where linesmen are working, trying to restore power, who would be put at risk of electrocution.

Any approved inverter therefore permanently monitors the grid and as soon as the grid becomes unstable, will disconnect immediately. That happens during power outages but also if the grid experiences excessive fluctuations in voltage or frequency. Once the grid is back to normal, the inverter will automatically reconnect.

It is very important that your inverter is configured properly, to cope with the known instability of the WA grid. An inverter installed with 'factory settings' is likely to have parameters that will cause it to shut down much too often, resulting in reduced electricity production for no good reason.

Energy efficiency

The simple reason for suggesting this approach is cost. Efficiency measures usually save money in a very short period of time. Solar hot water systems need a few years before the savings have recovered the cost. Photovoltaics still needs more than a decade to pay off.

• Get a clear idea of your energy usage. Utility bills plus dockets from fuel purchases for your car is all you need to start.
• Once you know how much you consume, compare with friends and neighbours or against benchmarks published on various websites.
• Concentrate on the areas where you are 'above average'. If your electricity bill fits that description, have a go at the Synergy calculator. After you step through the flash animation and read the tips, take your time to adjust the 'daily usage' for each item. See if the calculator comes up with a number very close to your bill. It worked for us! If not, there is a big chance to identify all those hidden consumers: take the list you compiled and compare it with the actual items in each room.
• If you can't explain your electricity bill using that calculator, there is one more useful tool: a plug in power meter that is placed between a device and the power outlet. It can measure how much a device really consumes.
• There are various other online resources that will help you find more information (see our links page).
• And of course: when we come for a site inspection, ask us for tips.

CO2 reduction by PV

The Australian Greenhouse Office (AGO) publishes statistics that are updated on a regular basis. The 2008 edition quotes a 'Fuel cycle emission factor' from electricity purchased from the grid in WA (South West Integrated System, SWIS) of 0.98 kg CO2/kWh. In other words: every unit of energy you consume from the grid will have released almost 1 kg of CO2 into the atmosphere.

Our recommended grid connect system will help you to avoid over 1.7 tonnes of CO2 every year (1750kWh*0.98kg/kWh=1715kg). Over the system lifetime more than 40 tonnes of CO2 are kept away from the atmosphere.

To better illustrate that magnitude: a car engine emits 2.5 kg of CO2 for each liter of petrol it burns. The 1.7 tonnes of CO2 avoided by a grid connect PV system are therefore equivalent to reducing petrol consumption by 680 liters. If you have a small car, with a petrol consumption of 6.5l/100km, you would have to reduce your mileage by over 10,000 km every year to have the same positive effect you can achieve with our recommended grid connected PV system.

Assistance helping you to purchase a PV System

Solar Homes and Communities Plan - SHCP

Quoting the following from the application guidelines:

The Australian Government introduced the Photovoltaic Rebate Programme to encourage the long-term use of photovoltaic technology to generate electricity from sunlight and to increase the use of renewable energy in Australia. Key objectives are to:

• reduce greenhouse emissions;
• assist in the development of the Australian photovoltaic industry; and
• increase public awareness of renewable energy.

Please refer to the application guidelines for the full list of requirements. The main conditions are that the system has to be installed on your owner occupied principal place of residence by a BCSE accredited designer and installer. Since May 2008 the rebate is means tested and only available to households with a taxable family income below $100,000.

The SHCP is scheduled to end via 'a smooth transition' by the time the new Solar Credits scheme commences in July 2009. When exactly the last applications for the SHCP will be accepted is everyone's guess. If you qualify it might pay not to wait until end of June before lodging your application.

Renewable Energy Certificates (RECs)

Renewable Energy Certificates were first introduced in the Renewable Energy (Electricity) Act 2000 as a means of enforcing the mandatory renewable energy target. Companies, mainly energy producers like Western Power, who can not meet their own obligations for producing renewable energy, will buy those certificates from people who produce renewable energy.

By installing a photovoltaic system you become a producer of renewable energy and are entitled to claim RECs. The number of RECs depends on the size of the photovoltaic installation, the location (by postcode) and the amount of time that you claim RECs for. At the moment, for a PV system, you can generate RECs for 15 years in advance and sell them right after your system has been commissioned.

For our recommended system (1050W), when installed in the Perth metropolitan region, you can create 21 RECs. RECs are traded and the price fluctuates with supply and demand. Since the change of government with subsequent ratification of the Kyoto protocol the value of RECs has increased substantially. At the moment you can expect to sell them for $40 each, a total of $840 for your system.

Whether you sell your RECs, never create them, or surrender them voluntarily is entirely up to you and will be a moral choice. By surrendering your RECs you can truthfully claim that the energy you produce is completely green. If you sell your RECs it can be argued that by doing so you have allowed a big power company to reduce their own investment into renewable energy (by paying you instead).

If you want to sell your RECs we will assist you in doing so. We are in contact with an agency that buys RECs from individuals and on-sells them in bulk to the big power producers. For more information see our link section.

Feed in Tariffs

Feed in tariffs are the way to go if a government is serious about stimulating private investment into renewable energy. The most successful model so far can be seen in Germany, where in the year 2006 alone 950 MW of new photovoltaic systems were installed. That amounts to 130% of the total cumulated installations world wide that had been done by the end of the year 2000 (729MW). A truly staggering rate of growth! Other countries in Europe are catching up at a fast pace, Italy and Spain in particular. Some US states, like California, follow a similar path.

The cost of a feed in tariff is usually carried by the community as a whole. Power prices rise a little bit to compensate for the higher prices paid for renewables. The actual cost for those schemes, even in countries like Germany that have increased their renewable energy production dramatically, is minuscule; a low single digit percent increase in retail electricity prices. The benefits for the community far outweigh that cost: new jobs, cleaner air and of course lower CO2 emissions.

Where a feed in tariff is implemented properly, each kWh produced from renewable sources is measured and then credited at that high price. A German house with a PV installation on the roof has two independent meters, one that measures all electricity that is produced by the solar power system and then fed into the grid, and one that measures the electricity consumption of that household. Units from those meters are converted into Euros using different prices, the higher feed in tariff for the export meter, the retail electricity price for the import meter.

Unfortunately the feed in tariff for South Australia, scheduled to be implemented 1/7/2008, continues with the current practice of 'net metering'. One single meter measures how much electricity flows in and out of the grid, but only after the owner's consumption has been netted off against the production. Effectively that means that people with PV systems will pay the highest electricity prices around for their own consumption, as they don't get proper credits for all their renewable production.

We have written to the WA Minister for the Environment and Climate Change to inquire about the status of discussions regarding feed in tariffs for WA and to ask him to avoid this improper implementation of an otherwise very good scheme. Check back occasionally, once a reply is received this information will be updated.

Insurance

A photovoltaic system is a valuable addition to your home. Even though you may only pay $4,000 for it, it is worth the full amount it would cost without rebates, close to $13,000. Please call your insurance company to find out if a PV system is covered as part of the home insurance (it is with the insurer of our home, Vero). In any case it might be prudent to adjust the sum insured to reflect the added value.