STCs - Eligible small-scale renewable energy systems are entitled to a number of Small-scale Technology Certificates
(STCs). The number of STCs that can be created per solar system is based on its geographical location, installation
date, and the amount of electricity in megawatt hours (MWh) that is generated by the small-scale solar power
system over the course of its lifetime of up to 12 years. This means that, in Perth, for a 6kW system you can receive
STCs to the value of around $4,000 which will cover roughly 50% of your install cost.
Feed In Tariff - This incentive is when the power companies pay you for the excess power your system produces
and pumps back into the grid. Currently the feed in tariff for WA is approximately 7cents per unit (kWh). So if your
system produces 25 units and you use 15 units, the remaining 10 units you will export back into the grid at 7cents
each. That works out 70cents total per day, which is $255.50 per year and over $1,200 every 5 years.
Power prices in Perth are high and on the rise. A recent Australian Energy Market Commission report (Dec16) has
forecasted the average price of electricity to grow by 14.5% over the following 2 years. That’s an increase of nearly
double the national average over the same period.
The first thing to look at when deciding what size solar system you will need is your current power usage. This can
be found on your most recent electricity bill. Your bill should include your average daily units used over the billing
period, this is measured in kilowatt-hours (kWh). If you can, it’s a good idea to look at 12 months worth of bills to
see how your usage changes throughout the year.
For reference purposes, the average Perth household consumes around 18kWh of electricity per day. The rule of
thumb for Perth is that every 1kW of solar panels installed will generate an average 4.4kWh of energy per day. So if
your daily consumption is 18kWh then you will need a 4.1kw solar system to match to your consumptions needs.
Another important consideration when sizing up your solar system is the amount of space available on your roof,
especially on the prime north facing section. If you have other things already taking up space on your roof i.e. Solar
hot water system, aircon etc then you will have to work around these when deciding where to place your solar
panels. If space is limited on the north facing section of your roof, which it often is, then you will need to look at
either the east or west facing sections to fit in the remaining panels. Bear in mind that panels placed with a directly
East or West facing orientation will not produce more than 85% of their rated output so you will need to add more
panels to your solar system in order to generate your desired output.
1. Look into the different panel tiers 1,2,3 (do you want high, medium or bottom end panels).
- Tier 1 are the bigger brand panels (Trina, Canadian Solar, SunPower, JA Solar, Hanwha QCells)
- 80% of lower tier panels are not good quality
2. Warranty on products (performance & manufacturer’s)
- Performance warranty is 25 years
- Manufacturer’s warranty varies (shouldn’t be less than 10 years)
3. Power tolerance
4. Efficiency (this should be over 14% - unless roof space is critical, don’t stress about efficiency)
5. Temp coefficient (measures how much the power drops for every degree rise in temp)
- Ranges from -0.4% per degrees (good) to -0.5% per degrees (not as good)
6. Performance ratio (percentage that tells you how much power you can really expect to get from the panel)