A lot of emphasis is placed on efficiency of panels. For some brands it seems the whole marketing is built around the efficiency.
This is an important factor, but much less than many people think.
Let’s take two systems –
1. A 5kw using a 27 x 190w panels such as a Suntech panel which has about a 15% efficiency. (5.13kW system)
2. A 5kw system using 16 x 318w SunPower panels which have a 19% efficiency. (a 5.088kW system)
Now, apart from the minor system size, which is just caused by the different capacities of the panels, each system will output more or less the same amount of power. A 5 kilowatt system is a 5 kilowatt system.
The increased efficiency of the SunPower panels doesn’t mean that system makes more power.
It is like the old question – which is heavier, a pound of lead or a pound of feathers?
In other words, the stated output of the system already takes the efficiency into account.
What it does mean is that the total roof area used by each system is slightly different.
For example, the Suntech system will take up 35 m2. The SunPower system will take up approx 27 m2.
So it saves 8 square metres.
This is important if roof space is at a premium, for example if you were trying to fit on as much as possible on a roof. This is rarely the case.
In most cases, other factors have a bigger impact, such as the installed cost and the quality of the system.
SunPower, while excellent panels, for the same 5kW system example given, will probably cost about an additional $5000 – $8000 more for that system. Is the smaller ‘footprint’ worth that premium to you?
Rather than looking at the efficiency of the panels, we suggest you look at the following:
- is the panel from a reputable manufacturer?
- is the price reasonable?
- do they have local representation in Australia (in case the installer goes out of business, who can you turn to?
- the output warranties offered.
In most cases, a good quality crystalline panel will suit the Australian environment, but many are new and untested brands. We tend to look at brands in terms of Tier 1 and Tier 2, and would place Suntech as a Tier 1 brand.