Like with almost everything it is the small details that can make all the difference in the long run.We pay attention not only to the selection of the main components but to everything down to the last screw:
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:
Shop around. Ask questions. Then make an informed decision.
Sunpower Solar ModulesSunpower modules are some of the highest efficiency modules available today.
The SPR 225 has 18.1% module efficiency
The SPR 210 has 16.9% module efficiency
Why does this matter? A system designed with high efficiency monocrystalline modules uses up a lot less space on your roof than others.
Not only will high efficiency modules be installed quicker (and therefore cheaper), it is also much easier to find a spot that has optimal sunshine and aesthetically blends in with your house. In addition you have a chance to conserve high quality sunny roof space for possible future uses like:
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.This is a real picture we took on our own roof, it has just been cut to size. SunPower modules look great and they perform extremely well:
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).For further details follow the links to the manufacturer's website.
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:
Schletter and Conergy Mounting RackThe parts of the mounting rack that come into direct contact with the solar modules are all made of anodised aluminium, the same material as the module frames, to avoid even the slightest chance of corrosion that would happen if dissimilar metals touch. All bolts, nuts and washers are made of high quality stainless steel.
Photovoltaic modules are classified by their 'peak power', in simple words that is the amount of electricity a module can generate in bright sunlight that falls perpendicular onto the module. Typical module sizes for current grid connect systems are between 150W and 220W. The Australian government subsidises systems up to 1000W with $8/W, up to a total of $8000 with the SHCP. As a result most arrays that get installed at the moment are made up of 5 to 7 modules, reaching a total output of just over 1000W peak (1kWp).
The amount of energy generated from a PV system is influenced by a lot of factors (see detail page), but most importantly by the array size and the amount of sun received. As the amount of sunshine that hits any fixed surface varies greatly throughout the day and for days in different seasons, usually an average value is quoted, the so called peak sun hours (PSH). In Perth we average about 5 PSH for the horizontal plane. That means we have each day, averaged over the year, the equivalent of 5 hours of full sunshine falling straight onto the ground.
Currently three main types of photovoltaic modules dominate the market:
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.
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.
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 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.
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.
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).
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.
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.Becoming more energy efficient is easy once you know how to go about it. The following list might help:
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.
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:
Applicants who fully satisfy the conditions for residential photovoltaic systems will receive a rebate of $8 per peak watt of output of the new photovoltaic component of the system up to a maximum of $8000.
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 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 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.What is a feed in tariff? It is a pricing structure that rewards climate friendly renewable energies by paying more to the producers of that energy. In the case of Germany the feed in tariff for photovoltaics started at about 4 times the regular retail price of electricity, over A$0.80/kWh. This price is locked in and guaranteed for 20 years for all installations that are completed in a calendar year. Each following calendar year the tariff for new installations is lower (but again fixed and guaranteed for 20 years), to compensate for technological advances and cost savings. This model gives long term investors the necessary security needed to plan ahead and encourages them to commit their funds.
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.
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.