Frequently Asked Questions
1. What do I need to know when buying Solar?
Q. How a PV Solar Power System works?
A. Solar panels convert energy from sunlight into Direct Current (DC) electrical energy. An inverter changes the (DC) into Alternating Current (AC) for your home’s electrical circuits. Any excess energy is fed back to the electricity grid, for which you will be paid a feed-in tariff.
Solar panels work best when they’re north facing, pointed directly at the sun, at an optimal angle and not blocked by trees or shading.
Q.Is your system retailer, designer and installer accredited?
A. The Clean Energy Council (CEC), is Australia’s peak body representing the clean energy sector, it accredits both installers and equipment. Also important is how much experience your installer has. Will the installer be around in 10 or 20 years if something does goes wrong?
Q. Does your solar PV system meet Australian Standards?
A. All equipment used should meet the Australian standards and be CEC certified. You can ask your installer to supply proof. You can check the CEC’s list of currently approved PV Panels Inverters and Modules to confirm.
Q. Solar incentives.
A. There are two main incentives that can help pay off solar PV systems: small-scale technology certificates (STCs) and feed-in tariffs (FIT).
STC’s are government incentives that help reduce the upfront cost of installing your solar PV system. The value of the STCs your system receives differs depending on its size and location and the market value of STC’s.
To be eligible for small-scale technology certificates, your solar panels must be CEC certified.
Feed in tariff’s is the $ amount your electricity retailer pays you for electricity your solar PV system feeds back into the grid. You will need to contact your power retailer to find out how much they will pay for the FIT. Here is the current Victorian FIT’s schedule (issued 30th July 2018).
Off Peak Weekday 10pm to 7am Weekend 10pm to 7am Rate: 7.1 c/kWh
Shoulder Weekday 7am to 3pm Weekend 7am to 10pm Rate: 10.3 c/kWh
Weekday 9pm to 10pm
Peak Weekday 3pm to 9pm Weekend n/a Rate 29.0 c/kWh
Q. How much capacity do you need?
A. See the Clean Energy Council guide to sizing a solar PV system to suit your home.
Your electricity bill will show you what your daily average usage is.
Q. Can the design of the PV system affect the amount of power produced?
Yes, a well-designed solar system can produce more power than a poorly designed system. A good system designer will visit the site and consider all the site factors and design a system to produce the maximum amount of power as well as considering all the issues regarding installation and operation.
Panel Direction: To produce the most power, panels need to be installed facing the direction that receives direct sunlight for the most hours in the day. In Australia that is North, then West, then East. Solar panels should not be mounted south facing.
Shade: Is a major issue that can dramatically reduce the power production of a solar system. The installation location of the panels must be as free from shade for as much of the day as possible.
Space: If space is tight a designer can select a larger capacity panel, to achieve the required power production in the space available. If the house does not have suitable roofs or space a good designer will look at what other options are available, sheds, pergolas etc.
Roof Pitch: The pitch of the roof affects the efficiency of the PV panels. The optimum pitch is 20-30 degrees. Roofs with a pitch under 10-degree should be mounted on stands to achieve optimum power production.
Inverter Location: The inverter location is also important, as the greater the distance between the inverter, PV panels and switchboard the more efficiency is lost.
2. PV Solar Panels
Q. What is the most important thing to consider when selecting what PV panels to use?
A. Solar panels are the most critical part of any solar power system. So having an accredited designer choosing the brand and type of panel, is just as important as making sure they are at the best angle and pointing in the right direction.
Things to consider when choosing PV panels are:
• Are the panels fully accredited and approved for use in Australia?
• Are the panel manufactures Tier 1?
• Does the manufacturer have an office in Australia to make warranty claims easy in the future?
• Do they have a 10-year product warranty and a 25-year performance warranty?
Q. What is the difference between Polycrystalline, Multicrystalline or Monocrystalline Panels?
A. This is one of the most hotly debated subjects in PV systems.
Polycrystalline and Multicrystalline panels are the same thing. They are made from a block of silicon that has multiple crystals and appear blue. Polycrystalline Panels are slightly less efficient 14-17.7%, however their advantages are they cost less to produce, they perform better in lower light conditions and have a higher temperature co-efficient.
Monocrystalline Panels are made up of cells of single silicone crystals and appear black. Their advantages are they are slightly more efficient at 14-24% but are more expensive to produce, are more fragile and have a lower temperature co-efficient.
Q. What difference does temperature make to a PV panel performance?
A. Temperature effects the efficiency and maximum PV output of a solar Panel. The hotter a panel gets the less power it generates. The ambient temperature coefficient affects the yield potential of a solar panel . All solar panel manufacturers are required to provide the temperature coefficient figures.
Q. What difference does shade make to a PV Panel performance?
A. Even a small amount of shade of any panels in the network affects the overall performance of the module. Simulations show that even 20-30% shading of the solar module will result in 30-40% reduction in the power output. This can be minimized by using an inverter with multiple MPPT (Maximum Power Point Tracking) which helps maximize the power output in partial shade, dusty environments and on cloudy, low light days.
Q. What difference does PV Panel efficiency make?
Efficiency is simply a measure of the panel’s electricity output (in watts) compared to its surface area. Generally, the higher the efficiency, the more power you can get from a given roof area. However, if you have plenty of roof space, it can be more economical to use less efficient panels and just use more of them.
3. Grid Tie Inverters
Q. What is the most important thing to consider when selecting what Inverter to use?
A. Quality. First make sure the inverter is approved by the Clean Energy Council for use in Australia and complies with the relevant Australian standard (AS4777).
Warranty: Quality manufacturers stand by their products and provide a minimum 5-year warranty with the option of having an extended warranty up to 10 years. If a manufacturer is offering a warranty less than 5 year the product generally has a higher likelihood of failing after the warranty expires. You want a manufacturer that has an Australian office to make dealing with any warranty issues simple.
Efficiency: To get the maximum power production from your PV array, you need to install an efficient Inverter.
Inverter efficiency is a measure of how well the inverter converts the electricity received from the PV panels into power. Most grid connected transformer-based inverters have an efficiency of around 93% or better. Transformer-less inverters are typically around 95% or better.
Maximum Power Point Tracking (MMPT) Inputs: Some inverters have two MMPT inputs. This allows two separate strings of panels to be connected to the inverter. (Required if PV arrays are being installed on two separate roofs say north and west). If one array is producing less power due to shading, the other array that is not affected will continue to produce maximum power.
Sizing: Inverters s come in different size capacity. The larger the inverter capacity usually the larger the cost. It is important to ensure the inverter size will accommodate the maximum amount of power produced by the PV panels you are installing. If an array supplies more power than the inverter’s maximum input capacity, (usually 10 to 30% of the kW size of the unit) the inverter process the excess power, but will waste the excess power as heat.
4. Battery Storage Systems
Q. Storing solar energy in a battery
A. A home storage battery lets you store the electricity generated in daytime by the solar panels for later use at night. Battery systems can effectively reduce power bills and system payback times.
Q. Are their different types of battery systems?
Yes, there are many different types of battery systems, the most common for household solar systems are:
• All in One Battery Systems that include an inverter with the battery in the one unit that is ground mounted.
In some All in One system the batteries come as battery packs, so you can adjust the size of the battery according to how many battery packs you add.
• Hybrid Battery Systems are added to existing inverters. They are usually supplied as a single size battery that is mounted on the wall.
Q. Will batteries provide power to a house during a power blackout?
Yes, during a power blackout the power stored in the batteries can be used to provide power to the house. The length of time of the battery back up will last depends on the level of charge in the battery at the time until the batteries power is drained.
• Hybrid batteries connected to standard Grid Conncet Inverters will switch off and go into Emergency Power Suppy (EPS) mode, and will not recharge from either the PV panels or the grid until power grid is back on.
• All In One battery systems will run in Full Off-Grid mode and keep storing PV power and re-charging the battery, extending the time of battery back up while the sun is out and producing PV power.
• All In One battery systems can also be connected to a generator and will switch to generator power when low and no grid or PV power is available.