Solar panels are increasingly being installed by homeowners who are worried by rising electricity costs, and who want a system that both cuts their bills and produces greener energy. We explain what you need to know before installing a solar photovoltaic (PV) system on your roof.
To size your solar panel system you need to work out how much electricity you use and when you use it.
As a guide, a typical home uses 20kWh of energy a day. A 5kW solar system would meet most of the daytime power needs of such a home.
How many solar panels do I need?
- The power output of your whole solar system matters more than the size or number of panels.
- The higher each panel's nominal power rating (and actual power output), the fewer panels you'll need (or the more power you'll generate).
- If you have plenty of roof space, you might find it more economical to buy cheaper panels with lower efficiency and just use more of them.
- The panels in our solar panel reviews are each about 1.6 square metres in area, but they vary in length, width and power output.
CHOICE tip: Fewer panels can mean a quicker installation.
An example: You could use four 250W Jinko panels, taking up 6.5m2 of roof space, to make a 1000W array. But four 327W Sunpower panels would take up the same overall area and form a more powerful 1308W array (although the Sunpower panels would cost you more).
How much do solar panels cost?
The average price across Australian capital cities for a 5kW system is $5100, and solar technology is only getting cheaper.
CHOICE tip: Compare prices for whole systems, not just individual panels.
It takes anywhere from two to seven years for a solar system to pay for itself – after that is when you can start counting the savings.
Payback times vary depending on where you live in Australia. The infographic below shows averages for capital cities.
There are two main incentives that can help you make money off your solar PV system: small-scale technology certificates (STCs) and feed-in tariffs (FiTs).
A home storage battery lets you store the electricity generated by your solar panels to use at night or on a cloudy day.
You may want to consider a system that includes battery storage; the Tesla Powerwall is the best-known solar battery but there are many other brands in the market. But generally, storage batteries don't make full economic sense yet for most homes.
- Assess what energy you currently use and the system capacity you need (and can afford).
- Check if your roof faces the right direction. Only north-facing panels will produce their full capacity.
- Ensure there are no trees, power lines or other structures shading your roof.
- Find out what local council approval is needed. Increasingly, local councils have staff on hand to help people make the best decisions on solar.
- Try to figure out your system's payback time.
- The inverter (which converts DC power from the panels into AC power for your home) is a key part of the system. See our guide to buying a solar inverter for all the details.
- If you're considering adding a battery, see our buying guide to solar storage batteries to understand the pros and cons of these.
- Get multiple quotes from installers to ensure you're getting a good deal, and make sure your installer is CEC-accredited (see below).
- Make sure your solar panels meet the required standards (see below).
- Check your solar panels' product and performance warranties; see below for what these are.
If you want to be eligible for small-scale technology certificates (STCs), your system must be installed by a CEC-accredited installer. The Clean Energy Council (CEC) is Australia's peak body representing the clean energy sector. It accredits both installers and systems that meet certain standards.
Look for a CEC-accredited company:
- that is a signatory to the CEC's code of conduct
- has been in business for a while
- has an established track record
- relevant experience
- specialist expertise, and
- a good reputation.
Retailers can also sign up to the CEC's voluntary code of conduct, which demonstrates a commitment to best-practice installation.
- Some materials can be made to produce electricity when light falls on them; this is called the photovoltaic effect. Solar panels use this to convert energy from sunlight into direct current (DC) electrical energy.
- An inverter unit then changes this into alternating current (AC) for your home's electrical circuits.
- Any excess energy can be fed back to the electricity grid or to your own battery storage system.
What are solar panels made of?
Most solar cells are made of silicon. Solar panels, also called modules, are each made of several solar cells (most in our test have 60 cells), connected together and sandwiched between protective glass and a backing plate. The whole panel is usually surrounded with an aluminium frame. A typical installation includes several panels connected together in an array.
Types of solar panels
Almost all panels used in home solar systems are mono- or multi-crystalline. While there are technical differences between these types, don't put too much consideration into this; it's much more important to consider other aspects such as price, rated power output, and warranties.
PHOTO: CSIRO Energy Centre