This table shows some key figures for different system sizes. Each column is explained in more detail below.
All values are for Sydney / ACT and are approximate only. Assumes an 'efficient house' consumes 10kWh/day.
What is a kilowatt?
Kilowatts, kW, are a measure of instantaneous power. Every load requires a certain amount of power to run, for example a 100W light bulb uses 100W, or 0.1kW, of power to run.
What is a kilowatt hour?
Kilowatt hours, kWh, are a quantity of energy. It is the amount of energy equal to one kilowatt of power over one hour of time. It is a common mistake to confuse kWh with kW. The difference is similar to that between km and km/h. The energy, measured in kWh, is the total amount of energy used over a certain time whereas the power is the instantaneous value required. For example, a 100W light requires 0.1kW of power and if left on for 24 hours will consume 2.4kWh of energy. A 2.4kW air conditioner will use the same amount of energy in just one hour as it requires more power to operate.
What is a 'load'?
In electrical terms, a load is anything that consumes electricity. Typical loads within a house include lights, appliances etc, although the whole house can be considered as a 'load' on the grid.
What is PV?
Photovoltaics (or PV) is a technology that utilizes a semiconductor to convert the light directly into electricity. It does so silently, without any moving parts and with no emissions or waste products given off during operation.
How long has PV been around?
The first modern photovoltaic device was built at Bell Labs in 1954. It was a primitive device that converted only 6% of light into electricity but it set the blueprint for the vast majority of commercially available solar cells today.
Although initially only used in space applications, as production methods improved and costs came down, solar cells became viable for remote, terrestrial applications with Telecom Australia one earliest companies to use large scale PV systems for remote telecommunications sites. Some early test sites installed in the early 1980s are still in operation today, despite the immature nature of the modules used in these sites. Modern solar modules are much more robust and should last significantly longer than these early versions.
What happens when the sun goes down?
PV systems can be classified as either ‘Grid Connected' or ‘Stand Alone.' Grid connected systems are connected the standard electricity grid which is used as a kind of pseudo battery. During the day, any power that the system produces in excess of what is needed is fed out through the meter into the grid, turning the meter backwards, or clocking up a credit. When more electricity is required than is provided by the PV system, such as during the night, electricity is drawn in from the grid as per usual. This happens automatically with no action required by the user.
Stand Alone systems are used in areas where there is no grid available and make use of batteries, or other energy storage devices, to store energy during the day for use at night. The batteries add to the cost of the system so stand alone systems are generally not recommended in areas where a grid connect system is possible.
What happens during a blackout?
Grid connected systems are required to shut down or disconnect from the grid in the case of a black out. This is to protect line workers who might get electrocuted while working on the ‘dead' line if a PV system nearby is sending power into the lines. In order to maintain power during a blackout, a battery backup system is required. This gives some level of storage and more importantly adds a stand alone inverter which is capable of running independently of the grid. Click here for more information on battery backup systems.
What sized system is right for me?
This will vary depending on how much electricity your household or business requires. Grid connect systems are very flexible and allow for any portion of the house's power requirements to be covered by the solar with the rest covered by the grid. Stand alone systems however need to be carefully planned to ensure that enough power is provided. Contact us to talk to our helpful staff about choosing the right system for you.
How much will it cost?
Grid connect PV systems can be sized to meet an portion of the house's electricity requirements and can therefore be sized to meet your budget. Typically a quality PV system costs anywhere between $4,000 for a fairly small system up to $30,000 for a large system depending on the size and equipment used. This includes rebates, installation and GST. Put simply: you get what you pay for. Solar power systems, like any electrical installation, vary substantially in quality from module efficiency and ability to actually perform as specified to the mounting, wiring and other components used which will affect both the system power output and the lifetime of the system. If you care about quality, whether it is engine in your car or television you choose to watch, solar panels are no different!
How much power will the system produce?
This will depend on the size of the system installed and the amount of sunlight that reaches the modules. The number of panels doesn't matter so much as the total system size. Some systems have a slightly higher number of smaller panels and some have slightly fewer larger panels. Neither is better or worse in general but different layouts may fit better on individual sites. See the table at the top of this page.
Will the modules be mounted on my roof
It is most common for PV systems to be mounted on the roof, however it is possible for them to be mounted on the ground. This is usually only suggested if there is limited roof space or regular shading.
How much space does the system need?
This will depend on how many solar modules you wish to install. Each kW of PV panels requires approximately seven to eight square meters of space. The table at the top of this page shows the area required for various system sizes.
Do the modules need to face north?
It is ideal for solar modules to be north-facing, however it is also possibly for them to face east or west with only a small loss in output.
The reduction in output for aspects other than due north will depend on the latitude of the site and the slope of the roof. Steep roofs in southern latitudes will lead to greater losses than flatter roofs in more northern latitudes. In some cases it may be more financially beneficially to install panels facing west or north west to make use of peak electricity tariffs in the afternoon, although generally north is best.
Can solar modules work in the shade?
Any solar module's output will be decreased or cut-off if there is shading. Some solar modules will manage shading marginally better than others, but anyone who tells you that their solar panels work well in the shade is providing incorrect information. A standard trick is to measure the voltage of a shaded module to show that there is still almost as much as when it is in the sun, however this ignores the fact that there will be very little or no current produced from a shaded module which means no power, regardless of the voltage.
How long will the system last?
Kyocera Solar PV modules have a design life of several decades. In fact, some of their earliest sites installed in the 1980s are still in operation now, despite the relatively primitive technology and manufacturing processes of that time. This is because solar panels are remarkably simple devices with no moving or wearing parts. Solar module warranties are generally 20 years, significantly longer than most electrical appliances.
The other system components such as inverters, frames, regulators etc are designed to last as long as possible, if not the whole life of the system. Good quality grid connect inverters such as the SMA Sunny Boy range are designed to last 20 years with a 5 year warranty. Autonomous Energy use engineered mounting frames designed to last the life of the system and with a 10 year warranty.
Are the modules fragile?
All approved solar modules must pass some minimum tests which include a hail damage test in which a steel ball one inch in diameter is dropped on the centre of the panel. Autonomous Energy's preferred brand of modules goes much further with a very sturdy frame incorporating a boxed in section to give extra strength.
Will my solar modules be damaged in a hail storm?
All PV modules must pass a hail test to gain IEC certification. Autonomous Energy has twice had to undertake insurance jobs to remove and reinstall the undamaged PV arrays after the roof on which they were installed was so badly damaged by hail that it had to be replaced. In both cases this was covered by the home and contents insurance and was completed at no cost to the home owners. See our customer's story of how their solar modules survived a vicious hail storm that destroyed their roof.
What maintenance is required?
No regular maintenance is necessary. A log of the energy production taken from the inverter screen will allow any problems to be quickly identified but is not necessary. Cleaning soiling such as bird droppings from the panels will help to maintain peak power levels but is only recommended for easily accessible systems, such as those installed near an attic window. Generally PV modules on a slope of 10 degrees or more will self clean sufficiently in the rain.
Will installing a solar power system affect the value of my property?
PV systems lose very little value over time and would be an attribute to a property's sale price. They reduce the operating cost of a property and to many buyers will add value for environmental reasons. In the case that a prospective buyer strongly disliked the system it could be quite easily removed and reinstalled at another site.
Are the batteries reliable and how long will they last?
Good quality deep cycle batteries are quite reliable and last up to 10 years if well managed and maintained. Proper care is necessary, especially for flooded types. There are several types of batteries available which require different levels of care and maintenance with low maintenance batteries and control equipment costing slightly more. A maintenance handbook is provided with all stand alone and battery backup power systems detailing the proper battery maintenance procedures.
How much greenhouse gas emissions are reduced by solar energy?
Australia has some of the most greenhouse polluting power stations in the world, with CO2 emissions per energy produced marginally better than India but worse than China and more than twice as high as the EU. The upshot of this is that reducing the amount of grid power required in Australia will have a greater effect reducing climate change than almost anywhere else in the world. A 1kW system will save approximately 1,400kg of CO2 emissions every year. By comparison a hybrid car (highly recommended) will save approximately 1,240kg of CO2 emissions per year (based on 20,000km/y) at an additional cost of $12,200 (based on Honda Civic).
The table at the top of this page shows the annual emissions savings for different sized PV systems
How does a solar PV system save water?
Most electricity in NSW is produced by black coal fired power stations which use 1.5L of fresh water for every kWh of electricity produced, mostly for steam production. By using renewable energy such as solar power you can help reduce the amount of precious water consumed for electricity production.
Do I have to insure my PV system?
It is a good idea to insure your PV system, which generally comes under standard home and contents insurance. Please seek advice from your insurance provider or an insurance consultant.