Frequently Asked Questions - Solar Electricity
What are the differences between solar electricity and solar hot water?
Solar electricity systems convert sunlight into electricity whereas solar hot water systems utilise the heat of the sun to generate hot water.
Greenline evacuated tube hot water systems are a particularly effective means of heating water for household use. Click here for more details about Greenline evacuated tube hot water systems.
What does PV mean?
PV is short for photovoltaic. The photovoltaic effect occurs when specially fabricated materials create electricity by being exposed to sunlight.
Photovoltaic (PV) solar electricity panels have been used on Australian buildings for over 40 years. They are of a relatively simple construction with no moving parts.
Greenline PV solar electricity panels are designed to provide free electricity from the sun over a typical lifespan of more than 25 years.
What are the differences between the various types of solar electricity panels?
There are 3 common types of solar electricity panels: monocrystalline, polycrystalline and amorphous.
Greenline solar electricity panels are monocrystalline panels. Monocrystalline panels are a proven technology and have been in use in Australia for over 40 years.
In most circumstances monocrystalline panels are more efficient than polycrystalline or amorphous panels. This means that monocrystalline panels can produce more electricity from panels that are smaller in size. Significantly, the total roof area required for a monocrystalline system will be less than that required for a polycrystalline or amorphous system of the same kilowatt (kW) output capacity.
This has obvious benefits when the available un-shaded roof space is limited. Furthermore, monocrystalline panels have a very long life span and performance is only likely to drop off by as little as 0.5% per year.
Are Greenline solar electricity systems installed by Clean Energy Council (CEC) accredited installers?
What does an inverter do? Do Greenline supplied inverters conform to Australian standards?
An inverter is a device that converts the direct current (DC) electricity from solar PV panels to alternating current (AC) for normal use via standard power points.
The efficiency of an inverter is a measure of its capability to convert DC electricity to AC electricity with minimum loss.
Greenline solar electricity system inverters are manufactured to high tolerances and typically operate at 97% plus efficiency.
Greenline inverters comply with Australian standard AS4777 and have an expected life span of 25 years.
What does grid-connected mean?
The electricity grid is the network of power lines that connects most buildings to the major power stations.
Normally electricity flows from power stations along transmission lines and into buildings via building meters and switchboards. However electricity may be generated in other locations from a variety of different sources (including photovoltaic panels) and be fed into the electricity grid via bi-directional electricity power meters.
A grid-connected solar electricity system is one that can feed electricity back to the grid; hence, 'feed-in' electricity.
What does feed-in mean?
A grid connected solar electricity system may feed electricity not required in the premises back into the mains power grid.
What's a feed-in tariff?
In most cases, power companies are obliged to pay customers for solar electricity fed into the grid according to a feed-in tariff. Feed-in tariffs may be at a standard or a premium rate and vary across Australia.
A feed-in tariff will substantially decrease the pay-back period for a solar electricity system.
Positive cashflow from a feed-in tariff is generally received as a credit on your electricity bill and, in most cases, is effectively tax free!
Can I store solar electricity produced by my solar system in batteries? What is an off-grid solar electricity system?
A solar electricity system that is not grid-connected is referred to as being off-grid and will require batteries to store electricity generated during daylight hours for use at nighttime.
An off-grid solar electricity system will not benefit from feed-in tariffs, but nor will it experience power outages due to grid electricity failures!
An off-grid solar electricity system will still attract Small-scale Technology Certificate (STC) rebates.
In circumstances where a new connection to the mains grid may be expensive - such as at rural properties - an off-grid solar electricity system with battery back-up may be an excellent, cost-effective alternative. Even at relatively small rural properties where the premises are as little as 50 meters from the street power lines, connection to the grid could cost as much as $20,000. This money may be better put towards an off-grid solar electricity system.
A well-ventilated storage space large enough to house the batteries will be required. The customer may then enjoy a completely sustainable electricity supply, no grid outages and no electricity bills at all!
Is my deposit paid to Greenline for a solar electricity system refundable if I find that the costs of grid connection charged by my electricity retailer are unaffordable?
What are STCs? Can I keep or trade STCs?
The Australian Government's Renewable Energy Target (RET) scheme aims that at least 20% of Australia's electricity comes from renewable sources by 2020.
The RET scheme employs a system of renewable energy certificates which are effectively created by the installation of large-scale and small-scale renewable energy systems. The certificates created by the installation of small-scale renewable energy systems - such as household solar electricity systems - are known as Small-scale Technology Certificates (STCs).
The number of STCs that are created by the installation of a small-scale renewable energy system is related to the electricity generating capability of the system and the installation location.
STCs are tradable certificates and may be bought and sold via an STC Clearing House. The cash value of STCs varies according to supply and demand.
Most Greenline customers opt to sign the STCs created by their installation to Greenline's nominated STC trading company. In return, customers benefit by receiving a point of sale discount on the total system value. The discount is equivalent to the value of the STCs at the time the customer's deposit is accepted. Otherwise, customers may choose to keep or trade the STCs themselves, but will not receive the discount on the installation and will need to attend to the necessary paperwork themselves.
What are Solar Credits?
Solar Credits is an Australian Government program whereby households, businesses and community groups receive additional Small-scale Technology Certificates (STCs) in relation to the first 1.5kW of the capacity of their small-scale solar system.
At present, under the Solar Credits program, the number of STCs created by the first 1.5kW of a small-scale solar system is multiplied by a factor of 3. From the 1st of July 2012 this 'multiplier' factor will be reduced to a factor of 2. From the 1st July 2013 there will be no multiplier and the Solar Credits program will be closed.
What is a Premium Solar Feed-in Tariff?
A premium solar feed-in tariff is available to eligible customers of electricity retailers. The system of premium solar feed-in tariffs varies across Australia. (NB Victoria's Premium Feed-in Tariff scheme has now closed to new customers).
Eligible customers will meet the criteria applicable in their state or territory. Typically an eligible customer will be applying for their primary residence or business premises. Community premises may also be eligible.
Generally there is a maximum size limit on the kW capacity of the system to be installed and the maximum amount of electricity consumed in the premises.
An eligible customer will receive a credit on their electricity bill for electricity that their solar system feeds back into the grid. This will be electricity generated in excess of that consumed within the premises.
On a premium tariff, the customer will be paid significantly more for electricity they feed in to the grid than they pay for electricity they consume from the grid. In some case 2 or 3 times as much.
Most customers will be significantly better off with a premium feed-in tariff than they were before installing a solar electricity system. However, if a customer uses more electricity during daylight hours than their solar system produces, they will have no excess electricity to feed-in to the grid and will therefore receive no credit for fed-in electricity. In many cases customers who opt for premium feed-in tariff will lose off-peak rates that may effect the cost of their night time electricity consumption. Customers should assess their electricity consumption, the value of existing off-peak electricity rates and the capacity of the proposed solar electricity system before locking into a premium feed in tariff. Greenline can help with assessing these factors.
Customers should also shop around electricity retailers for the best terms and rates. Some retailers will pay a higher premium feed-in tariff than mandated by government. However it should also be noted that not all retailers will pay customers cash for premium feed-in credits that are in excess of the customer's consumption. In other words, once a customer's bill reduces to zero - no additional cash payments from the retailer will be forwarded to the customer. The answer is to contact retailers and compare the details of their billing systems.
Nevertheless, assuming a solar electricity system is well matched to a customer's premises and usage, and depending on the tariff system applicable, a premium feed-in tariff can offset the initial installation cost of a solar electricity system in as few as 5 years.
How long does it take for a solar electricity system to offset it's own embodied energy?
The embodied energy of a solar panel is the total energy that is required to manufacture, transport and install it.
There are many complex factors in estimating the total amount of embodied energy 'held' within a solar panel. Expert opinion varies, but it would seem that after a period of somewhere from 4 to 7 years, the environmental benefit of a solar panel will have completely offset its embodied energy.
Given that the expected lifespan of a Greenline solar panel is 25 years or more, the embodied energy will be comfortably offset relatively early in the system's operating life.
Furthermore, most solar electricity panel mounting (racking) systems used in Australia are made from aluminium. The production of aluminium requires relatively high amounts of energy, so aluminium racking systems have correspondingly high embodied energy. Greenline however utilises galvanized steel racking systems that offer long-term strength and durability with the added benefit of significantly lower embodied energy.
How much area is required on my roof for solar panels?
Simply put, the more unshaded, north facing roof you have available, the more panels can be installed. More panels equals more electricity!
The roof area required for solar panels is related to several factors: the desired electricity output capacity of the system measured in kilowatts (kW), the geographical location of the system, the angle of the panels in relation to true north, the pitch of the panels in relation to the horizontal, and shading from trees and other objects or structures.
For example, a 3kW system set up on a north facing Melbourne rooftop at 38 degrees to the horizontal - with no shading, will require 17 x 180W panels. Greenline's standard monocrystalline panels are approximately 800mm x 1600mm in size, therefore there will need to be north facing roof space available to accommodate 17 x 800mm x 1600mm panels. The panels may be placed together in one place, or may be separated into groups (or arrays) in different areas of the roof to capture the most northerly sunlight.
What is the ideal angle of solar panels on my roof?
There are 2 angles to consider in relation to the installation of solar panels. The most critical angle is in relation to true north. Ideally panels will be installed to face true north or as close to true north as is feasible.
In some circumstances, solar electricity systems may be designed so that panels may be mounted on east, west or even south facing roofs by employing special mounting systems that re-orientate the panels to face north. However, the design of such mountings needs to take into account shading caused by the ridge of the roof.
The other angle that will effect system performance - but less critically than the angle to true north - is the angle that panels are mounted in relation to the horizontal, or their pitch. Panels will produce electricity even if installed completely flat, however the ideal pitch of panels is equal to the geographical latitude of the property. In Melbourne, for example, this is approximately equal to 38 degrees, whereas in Brisbane it is equal to approximately 27 degrees. Building roofs vary in pitch from virtually flat to as steep as 45 degrees or possibly more, although most contemporary Australian household roofs are usually around 23 degrees. Houses built prior to the 1940's may have steeper roof pitches of around 30 degrees.
If the roof pitch happens to be close to the geographical latitude angle of the building, then the panels will work effectively if installed flush to the roof surface. This of course minimizes the visual impact of panels too. If the roof pitch angle is not approximately equal to the geographical latitude angle, then a racking system may be employed so that the panels are tilted to the ideal pitch.
Increasing the pitch of panels also has the benefit of improving self-cleaning when rainwater runs off. Clean panels will perform better than dirt covered panels.
If panels cannot be feasibly mounted at the ideal angles to the sun and the horizontal, then an option is to add extra panels to the system that will offset the drop-in performance.
What's an actuated solar panel system?
The ideal system for panel mounting is an actuated system whereby panels are motorized and can move to track the sun across the sky for maximum sunlight at any time of day.
These systems may follow a fixed arc each day; or, in more sophisticated systems, may have sensors so that each panel may tilt independently towards the area of strongest sunlight in the sky. At some times of day, the best possible direction for a panel to face may even be to the south if say, the sun goes behind dense clouds to the north leaving the southern sky brighter!
Do all the solar panels need to be mounted in the same area of my roof?
Panels may be separated into groups in different areas on your roof - also known as split arrays - so as to maximise the opportunity for un-shaded, north sunlight.
Separating panel arrays may in some cases slightly increase the cost of installation; however the extra cost will be offset by improved system performance over time.
Where will my inverter be installed? Where should an inverter not be installed?
Ultimately the installation Electrician will determine the ideal location of the inverter.
Inverters may be installed indoors or outdoors. Inverters designed for outdoor use may be installed outdoors or indoors, however indoor inverters can only be installed indoors.
Outdoor inverters are designed to withstand weather and are generally more expensive than indoor inverters.
An inverter converts DC electricity from the solar panels to AC electricity that can be fed in to the premises; so, the inverter will be located somewhere along a wiring path between the solar electricity panels and the premises' electrical switchboard.
An inverter must be installed on a vertical wall. It must be at least 1.2 meters above the floor or ground. It must be a distance below the ceiling or eave above it equal to at least half the height of the inverter itself. There must be 100mm clearance around each side, the top and the bottom of the inverter. The inverter must be in a well-ventilated location; i.e. not in a sealed cupboard.
There are several places where an inverter should not be installed. It must not be near sources of steam; so bathrooms, kitchens and laundries are not suitable. Inverters should also be away from sources of corrosive vapor such as may be produced by swimming pool pumps or storage containers of chlorine.
The inverter should not be located where it may be a hazard to people passing by it, such as may happen in a narrow passageway. The inverter should not be located where it may be damaged by nearby activities or passing vehicles as may happen near the entrances of garages or workshops.
Like other such electrical devices (including switchboards), inverters do radiate an electromagnetic field. The effects of electromagnetic radiation on people at levels likely to be encountered in domestic situations are not completely understood - but are generally not considered to be dangerous. Nevertheless, as a precaution, we recommend that inverters not be installed on walls close to, or on the other side of which, people sleep or sit for long periods.
Our inverters are manufactured to high standards. They are quiet, but do produce a very low level audible hum. The hum will only be noticeable when the surrounding area is particularly quiet and you have your ear close to the inverter. Nevertheless, we don't recommend installing inverters where silence is required such as: bedrooms, library rooms, galleries or sound recording studios. Depending on its structure, the wall on which the inverter is mounted may have a slight resonating or amplifying effect on the inverter hum which may make it more audible if you stand very near to the inverter on either side of the supporting wall; however this is still not likely to problematic except in very quiet rooms.
Frequently inverters are installed outdoors near to switchboards or in garages.
What paperwork does Greenline take care of for me?
The installation process varies across Australia. In many cases Greenline will be able to assist you with getting the right paperwork to your electricity retailer, the electricity distributor and the electricity safety inspector.
Does Greenline use stainless steel bolts and nuts to prevent galvanic action in the panel frame or the mounting frame?
The aluminium panel frames of the solar panels need to be protected from oxidisation. Most installers also use aluminium for the mounting frames that hold the solar panels. Greenline installers however use hot-dipped galvanised steel for the mounting frame - including nuts and bolts. The galvanised steel will eventually oxidise as could be expected over decades – but it therefore also acts as a sacrificial anode and thus ‘sacrificially’ protects the aluminium panel frames from oxidisation.
How are the cables connecting the solar panels protected?
Cable insulation is UV stabilised and, if exposed to sunlight, will be further protected inside a conduit.
How will I know how well my Greenline solar electricity system is performing on a day to day basis?
The Aurora inverter provides this information on an inbuilt screen. Some models optionally enable wired or wireless monitoring via your computer.