How solar works on cloudy and rainy days may surprise you

"RENEWABLES are the dole bludgers of the energy system, they only turn up to work when they want to" said the ex-federal resources minister Matt Canavan recently.


After another rainy day in Casino, I decided to crunch a few numbers on this subject.

How does my solar system output in the last 12 (mostly rainy and miserable) days compare with the 12 days just before Christmas, at the peak of the drought?

I was pleasantly surprised.

My system has 6.6 kW of solar panels and a 5 kW grid-connected inverter.

It produces more energy than I use every day, even on the most miserable days.

In the 12 days of December, it produced about of 16 kWh per day, and in the first 12 days of February about 9 kWh per day.


Graphs for Jean Osanz's renewables column.
Graphs for Jean Osanz's renewables column.

In short, my system on a rainy day still produces 56% of what it does on a sunny day.

In my books a bludger does nothing at all, Matt.

And honestly this is what happens at night.

But there are not that many people who work all night.

In fact, adding a battery to my system can easily make it self-sufficient.

No need for a noisy and polluting back-up generator.

The only valid objection to renewable energies could be the initial cost.

I did some calculations about 10 years ago and found out that even then, the retail cost of off-grid solar power was in the same ballpark as industrial size coal or gas systems.

Since then the cost of solar energy has plummeted.

The graph below comes from an article called GENCOST 2018 published by the CSIRO.


Reference: GENCOST 2018: EP189502
Reference: GENCOST 2018: EP189502

Wind and solar plants are now the cheapest in terms of investment, with the exception of gas.

Forget about climate change, if you can.

On economic grounds alone there is no reason whatsoever to keep pushing and subsidising coal power plants.