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Solar Panel efficiency

A standard 60 cell solar panel is 1.627sqm in size

Efficiency is a measure of maximum power output divided by size.

65 years ago in 1954 a typical panel was 20 Watts (1.2% efficient).

10 years ago in 2009 it was 175 Watts (10.8% efficient)

7 years ago in 2012 it was 200 Watts (12.3% efficient).

2 years ago in 2017 it was 275 Watts (16.9% efficient)

In 2019, it looks like 300 Watts is going to be typical (18.4% efficient)

Some premium panels are already 19-21% efficient.


Who knows what ten further years will bring, perhaps panels will be replaced by solar roof paint, or solar glass bricks, but there is little doubt that efficiency is the benchmark by which solar companies measure themselves...and yet, it really means very little for most Perth homeowners. This is because most people hear the word 'efficiency' and incorrectly assume a more efficient solar panel installation will make more power than a less efficient one.


The typical maximum amount of panel power allowed in Perth is 6.6kW ... assuming that you wish to be paid by Synergy for your surplus solar power.


Therefore, working with 6.6kW, we can achieve that number by using 24 x regular efficient 275W panels, 22 x 300W panels, 21 x 315W panels or 20 x 330W panels.

On an unshaded, regular tilt, North facing roof in Perth they will ALL produce 32kWh per day on average across the year. The premium ultra high efficiency panels might give you an extra 1 kWh (3%) but it won't be any more than that and the extra output has nothing to do with their 'efficiency' and all to do with their technology for handling low light and heat. That extra 365 kWh per year is worth something between $95 and $25 depending on whether it is used up during the day or exported back to Synergy.


Whilst there is really very little cost difference between regular poly and mono cell panels, it's entirely likely that you will pay $2,000 to $4000 more for premium high efficiency panels, and yet the only real advantage is that you have 20 panels on your roof instead of 22 or 24.


If the efficiency improvements continue at the same pace as the preceding decades then it's likely that panels in 2029 will be 30% efficient and have 500W maximum outputs.