Solar Panel efficiency explained


We love the chart above produced by the NREL for its mind-boggling detail, and if you want to read their report on ever increasing solar panel efficiencies over time then this is their web page link.


To explain solar panel efficiency, you first need to know that in a solar panel factory they test their panels with an intense burst of 1000 Watts per Sqm of artifical sunlight. The panel then produces electricity, and just how much electricity it produces determines it's rated 'watts'. So, in 2019, it might well produce 330W, but back in 2012 the same sized panel produced 200 Watts.


So, to calculate the 'efficiency' of a solar panel you first take the physical size of the panel.


Let's take the Jinko Cheetah 330W half-cell mono panel as  our example.


So this Jinko physical size is 1684 x 1002 mm = 1.687 square metres.

Now we multiply that by 1000 (remember the flash test of fake sun?) to get 1687.

We now divide the 330W output by 1687 and we get 0.1956

So the efficiency of this Jinko panel is 19.56%

So, it converts nearly 20% of the sunlight that hits it in the test, into electricity.


The main point you should take away from this is that you need 20 of these 330W panels to achieve the typical 6.66kW that we are currently limited to in Perth residential installations.


If the panel was rated at 315W and had the exact same physical dimensions as the Jinko then the maths would be 315 / 1687 = 18.67% efficient and you would need 21 of these panels for 6.66kW


Or, if the panel flash tested at 370W and was the same size then its 370/1687 = 21.93% efficient and you would only need 18 of them for the 6.66kW limit.


Jinko themselves recently (June 2019) broke the World record for efficiency with 24.2% but we will never see THAT panel here in Australia, we only get the regular stuff as there aren't enough buyers here with deep enough pockets for that level of technology but wait another three or four years, and that level of efficiency is likely to be run of the mill.


65 years ago regular solar panels were 1.2% efficient

15 years ago , 10% efficient

7 years ago, 12% efficient

2 years ago, 17% efficient.


What will we have in another ten years?

Probably less than you might think. Like battery technology there is a LOT of money being thrown at improving efficiency and lowering costs, but it's the cost factor that limits the improvements. There is no point in new tech if no-one can afford to buy it.