Solar production after 3pm, and why it now matters in Western Australia

On August 30th 2020 the Government announced a radical change to the way that West Australians will be paid for their excess solar power. The renewable energy buyback scheme (REBS) or Feed in Tariff as it is more commonly known is changing for new solar customers. Those people who already have solar will remain as they are for now.


This is only the first stage. The next stage will be to remove the A1 tariff where we pay a fixed rate of 28.83 cents per kWh (inc GST) and move us to Peak/Off Peak pricing where a kWh in peak time (3pm to 9pm) will cost us about 60 cents.


Why are they doing this?
To fix an electricty grid that is on the brink of collapse. They want us to store surplus solar power in batteries rather than export it into the grid. They are building community batteries, but many home owners will end up getting their own solar batteries.


So, stage 1 is that we will be paid just 3 cents for our surplus power up until 3pm and then 10 cents after 3pm. Which begs the question, how much solar is produced after 3pm??


We have crunched the numbers from our customer base and the results are shown below...


6.6kW of panels on an East facing roof after 3pm, averages 1.76kWh per day

6.6kW of panels on a North facing roof after 3pm, averages 4.32kWh per day
6.6kW of panels on a West facing roof after 3pm, averages 6.01kWh per day


If we assume that your house will consume 3kWh of power between 3pm and when the solar shuts down for the day, then you can clearly see that there isn't going to be very much in the way of 10 cent payments for excess solar going on.


But wait a minute...
Just because they aren't paying us much of anything now for our surplus solar isn't going to stop that surplus hitting the streets. It's not like we can all change our power consumption habits and use it all up during the day. So the grid is still going to get all that power they don't want, so what's the point?


The point is...batteries.

Soon you will have a community battery in your local park and that huge battery will be charged up with the surplus solar, protecting the grid during the day. You can buy the power back at night from the battery. Some people who have a spare $8,000 or so will buy their own solar battery, but one way or the other, pretty soon, WA will be awash with batteries.


Selling the sizzle, or perhaps smoke and mirrors.
"How do we make it look appealing to get people to buy from these expensive new community batteries at 26 cents per kWh, or get them to buy their own battery?" the Government asked its advisors.


"Easy" the advisors replied, "Scrap the A1 fixed rate tariff and force everyone onto Peak/Off Peak pricing. Charge 60 cents per kWh after 3pm and suddenly 26 cents from the community battery looks like a bargain.


And those who buy their own battery will think "I can use my own battery power after 3pm and save myself 60 cents per kWh, and all it has cost me is a measly 3 cents per kWh that I would have been paid for my surplus if I'd sent it back into the grid"


And so it will be new solar users, and within a short amount of time, for existing ones as well.


57 cents per kWh from a 10kWh battery works out to be over $2,000 a year benefit and with a stroke of a Government pen, an $8,000 solar battery has gone from an eight year payback to four years.