Where does the Peak Demand value, on my bill, come from?

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My latest bill has a line:


Apr Demand     3.538kW               $0.xxxx         $yy.yy
(normalised for 30 days)


I undertand that the Demand value is derived from the highest kWh value in any 30 minute period during the peak demand hours on weekdays, not including public holidays.  The highest kWh 30 minute value is then divided by 2 to give the Demand value, which I would expect to see on the bill. That is, I should see a 30 minute value of 3.538 / 2 = 1.769.


However, when I look at the data downloaded from AGL, the highest value I see is 1.953kWh.


My question is how was the 3.538kW value determined?

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In SA our Distributor / Supplier SA Power Networks maintains a web site where we can visually view our hourly / daily / weekly / monthly / yearly usage for up to the last two years.


We can also download the data in a NEM format file (this is basically a comma separated value file) that lists your usage / generation in an easily read format.


I can also generate the same file from AGL's supplied file.


Now in the graphic example above you can see my Demand, Daily Usage and solar exported.


If I open the NEM format file I can see my DEMAND value in the file.


Have added a time line to the row for the date in question and can see that for the usage period 16:30 to 17:00 I consumed 0.929 kW.

This figure is the highest usage in the DEMAND time set by SA Power Networks (it is your supplier / distributor that sets this time).




Now in DEMAND you are charged per kilowatt hour, so this figure is for a 30min usage, so to get a kWh you multiply the amount by 2 ( to get 1 hours usage).


If I was on demand charge I would then have to pay the demand rate of 1.858 kWh if this WAS MY NEW PEAK RATE. (Over your demand rate period you always pay the HIGHEST rate multiplied by the number of days in your billing period).


As I have stated on other postings you do not have to use DEMAND rate tariff, YOU can select any tariff you like with any RETAILER you like.


When making the decision about using DEMAND you really need to know you usage figures and what your DEMAND rate is.


To limit your expenses you should also change to the shortest billing time.


Once again hope this helps.


You will notice this is the reading for the the date of 19th May 22, I am posting this on the 20th May 22 from data I downloaded at 06:15 this morning from SAPN, this same data will not be available from the AGL web site for (normally) two or three more days.



Cheers Neil


If this solves your Posting, please resolve this.

If you like the reply, please click the like button.


You should do this on all posts on any forum.

1 Reply 1017 Views



Thanks Neil.


I note everything you said.  


All I am asking is how did AGL get the Demand value of 3.538kW.


When I review the downloaded data for the month the highest value I see is 1.953kWh which produce a Demand value of 3.906kW.

FYI @David_AGL @jaydeny 


PS @NeilC I'm on monthly billing and the current plan, which includes Peak Demand, is by far the best for us. I have a spreadsheet which can run any plan over our historic data downloaded from AGL or Ausgrid.

1 Reply 1007 Views





"All I am asking is how did AGL get the Demand value of 3.538kW."


The answer is pretty simple look for a value of 1.769.


Remember it is not the highest value for the day but for the highest value in your demand period.


Cheers Neil


1 Reply 1001 Views



Thanks Neil,


Checked those things first.  Indeed 1.769 is in the file, but so is 1.953 and both values are within the Demand Peak times and on a weekday which is not a public holiday.


I suspect a bug in the AGL billing algorithm.  Not earth shattering, I saved 4.3c.  But my reason for posting was to clarify process.




1 Reply 1000 Views

Correction: I saved $1.29

1 Reply 995 Views

I have submitted a question via the AGL Feedback site.  Watch this space.

0 Replies 947 Views

Received a courtesy call from AGL in response to my feedback.


Our monthly billing cycle started on 15 April, but the Peak Demand is based on the calendar month, i.e. 1-30 April. The higher figure I was seeing was in the month of May.


Thanks for the clarification AGL.


FYI @NeilC