Electricity Pricing

I have rented a house.  Being the modern era, I need electricity.  Figured I would research electricity deals.

The end result was:

1. Origin was cheapest.
2. For my estimated usage, the total bill for the year is about $1.8 to $2k AUD 
3. There is only  couple of hundred dollars difference between the cheapest and the most expensive plans.

OK so onto the detail....

Initial research showed that standard costs were a charge per day just to be connected plus a cost per kWh.  Typically about $1/day plus 20c/kWh. 

I recall seeing a TV add where someone was offering a fixed price per month but I figured I have no idea how much power I will used and so I did not pursue those options.

I figured I could calculate my yearly usage as 365 x the connection per day charge plus 365 x the per kWh charge x amount of power used per day.

I had a look at the web site below to get an estimate of how much power a house uses
https://www.redenergy.com.au/living-energy/smart-homes/how-much-is-the-average-electricity-bill-in-australia

I chose that I expect that I would use 20kWh/day.

Next I went to the web and tried to find out how much it will cost. 
I looked at Origin, Enery Aust and AGL.
Then I though, before I go any further, I should get an idea of how much they are different from each other.  The cheapest things are shown in green below.
Cell B10 Shows energy Australia has the cheapest connection cost per day
Cell C4 shows origin has the cheapest usage cost per kWh
Cell G4 shows that for 20kWh of usage that the Origin plan is the cheapest overall.
Interestingly AGL are offering a $75 sign up credit but even if you subtract that off their prices, they are still more expensive than Origin.