To calculate energy and carbon savings for a new solar system, we estimate:

1. The cost of the electricity you buy from your retailer, via the electricity network (aka ‘the grid’);
2. How much of the 'grid' electricity might be replaced with electricity from the new or upgraded solar panels;
3. The difference between what you pay your retailer for 'grid' electricity, and what you’d pay if during the day more of your electricity consumption came from your new solar system (minus any ‘feed-in tariff’ you could earn for sending unused solar energy back to the grid).
4. The carbon emissions associated with the electricity if it was consumed from the grid (i.e. which may be avoided by using the solar system).

Of course, we can only estimate these amounts.  We’d need to know a lot more about your household to give more accurate figures – for example, the exact position, angle, size and shading of your roof can affect how much solar your system can harness to make energy. 

If you want to know more, here is a more detailed rundown of the assumptions and data we use:

• Usage data: We look at how much energy you currently use – and when – over a calendar year.  We drill down to work out how much you use, on average, in each hour of the day in a given month (e.g. between 10-11am in January).  Sometimes we can’t see your data for a full year.  If that’s the case, we ‘fill in the blanks’ with the closest available general AGL customer usage profile for the missing period. Similarly, if you have a ‘basic’ meter (rather than a ‘smart’ meter that records data throughout the day), we use a usage profile to estimate when you use energy within the day, and across different periods of the year. 
• Sunlight data: Solar panels mainly generate energy when the sun is shining.  We use a satellite database (‘PVGIS’) to estimate solar levels (“irradiation”) in your postcode, and the ‘intensity’ of that sunlight.²  This sunlight data is based on long-term averages from previous years.  Of course, we can’t predict the weather – we don’t know when it will rain, hail or shine at your house.    
• System estimates: Based on how much energy you use during sunlight hours, and an estimate of how much sun your home gets during the day, we estimate the appropriate size for your solar system (in kilowatts of power) and how much power that system would produce. These are rough estimates, based on assumptions. For example, we assume your system would lose some power due to shading (and other factors), but we don’t know how much shade actually covers your roof.³   
• Bill saving:  Your estimated bill saving for the 1st year is based on: (1) the usage charges you could avoid by using solar generated electricity in the day, instead of power from the ‘grid’; and (2) the ‘feed-in tariff’ you could receive by exporting any unused solar power to the grid.  These estimates are based on your recent electricity tariff/pricing (so your actual savings would vary with pricing changes). For certain tariff types with multiple rates (e.g. stepped tariffs), our estimates rely on assumptions about your tariff structure or rates⁴. If you don’t have a current feed-in tariff, we’ve used AGL's default feed-in tariff in your state⁵.  
• Carbon saving: The carbon saving is an estimate of the greenhouse gas emissions you might avoid by using electricity from the new solar system, instead of from the grid.  We have not accounted for emissions associated with the broader product lifecycle (e.g. manufacturing, installation or future disposal of the panels).  Your saving result is based on the estimated electricity generated by the new solar panels, multiplied by a recent average annual carbon intensity factor for grid electricity in your state⁶.  While the grid intensity factor is an average throughout a year across all times of day, the actual carbon intensity of daytime grid electricity (displaced by a standalone solar system) is generally below the average. This means your actual carbon savings may be lower than the estimate, depending on how much electricity usage you shift from the night-time to daylight hours (to take advantage of the solar panels). The carbon intensity of the grid is also an estimate only, based on historical data, which fluctuates over time.  This is why we only estimate carbon savings for year 1:  the savings are expected to reduce in future years, as the carbon intensity of the grid is expected to decline.          
• Payback period: This period is the estimated time it would take for your bill savings to equal the upfront cost of your new system.  First, we take the average installation cost from Solar Choice, 'How much do solar panels cost table' (February 2024)⁷  minus the approximate value of any applicable rebates.  We then estimate your potential bill savings.  Your actual savings depend on what will happen, over many years, to your energy prices and the performance of your system.  We can’t know that with any certainty - we assume that energy prices will increase at 3% per year, and that your solar system will degrade with age (based on solar panel manufacturer data). Please note that installing electrification products could incur other costs at your site, which we can’t predict – for example, customers with a basic meter may need to pay for upgrading to a smart meter if they install solar panels and/or a battery.

If your results include Solar + Batteries, the calculations are similar for solar panels (above) except for:

1. Size your battery: We find a potential size for your new battery.  We do this by looking at your electricity usage (if available) to see what you use beyond what you’d get from the solar system.  In other words, the battery would help you cover the energy you take from the grid at night (plus any consumption during the day which is not covered by solar).  If you already have solar and have selected a new battery only, we size your battery based on what you currently export back to the grid from your solar panels (on average).  The estimated installation cost for your battery (material and labour) is taken from an industry report (Sunwiz Australian Battery Market Report, 2023).⁸     
2. Bill savings: We estimate the additional savings you might realise by using energy stored in the battery instead of grid energy.  By using a battery, you’re unlikely to buy as much energy from your retailer, compared to if you only had solar panels.  However, you might also give up some of your solar ‘feed-in-tariff’ (because we assume you’d store some energy instead of exporting it).⁹  These are rough estimates based on averages – we’d need to know a lot more to give a more accurate figure, including how your battery is charged and used daily.

If you selected EV as a product of interest, you’ll have answered some questions about your current car, including the type of car (e.g. Hatchback, Sedan or SUV) and how much you use it on average.  Importantly, we’ve assumed that your new EV will be roughly ‘like-for-like’ – so you’ll drive roughly the same kilometres, and you’d buy roughly the same type of car (e.g. EV SUV if your current car is an SUV).

To estimate your running cost savings, we compare your current car and potential new EV by looking at:

1. Fuel costs: For your current car, we estimate how much fuel you use based on your car type, fuel type (e.g. diesel), the distance you drive, and ‘fuel efficiency’ (i.e. litres per 100km) estimates from the Australian Government  Green Vehicle Guide. We then estimate the cost of that fuel by using the latest monthly data from the Australian Government Petroleum Statistics.
   
   For a new EV, the ‘fuel cost’ is your cost of electricity to charge and run the car.  First, we estimate how much electricity you’d need for your current driving distances, based on range/efficiency data from manufacturers.¹⁰  We then estimate your electricity cost by using your electricity rate at 6pm in your home (or, for the “AGL EV Night Saver Plan” estimate, the rate under that plan for 12-6am charging).¹¹  This assumes you’d charge your car at home at that time - your actual savings could be higher or lower depending on when and where you charge your car, and how your energy prices change. 
   
   
2. Tyre and service costs: For both your current car and your potential EV, we estimate average tyre and servicing costs by using public data from the RACV Running Costs Survey. This data is based on private vehicles travelling 15,000 kms per year, and your actual costs will differ based on your own driving habits and exact vehicle.

To estimate your carbon savings, we compare:

1. Current vehicle emissions: The carbon emissions associated with the use of fuel (e.g. petrol), estimated using data from the Australian Government’s most recent National Greenhouse Accounts (NGA) Factors publication.¹² Once we have the emissions per litre of fuel, we use your annual vehicle usage and estimated fuel efficiency (explained above) to estimate the annual carbon emissions from using your current vehicle.          
2. EV emissions: Carbon emissions associated with the use of a new EV are annual emissions associated with the electricity required to charge your car.  Our emissions estimates are based on electricity sourced from the grid at average annual intensity for your state.¹³ In practice, the actual carbon emissions associated with your charging depends on when you charge your car (among other factors).  This is because the carbon emissions from the grid vary over time and are generally higher at night.  For example, your actual carbon savings from switching to an EV might be lower if you typically charged your EV from grid electricity at night, when the carbon intensity of that electricity is expected to exceed the annual average.

We have not estimated any emissions associated with the broader product lifecycle, such as the car manufacturing process, maintenance or the future disposal of the vehicle.

The Electrify Now tool only presents carbon emission savings for the 1st year.  Savings in later years may be likely to increase because the emissions intensity of ‘grid’ electricity is generally expected to decrease over time (as renewable generation supplies a growing proportion of grid electricity). 

If you told us you’re interested in an induction cooktop, you answered some questions about your current cooktop and the size of your potential new induction cooktop.  This helps us compare the two cooktops, to get a sense of your potential savings. 

To estimate your annual energy bill savings, we have estimated:

1. Cooktop usage habits: This is based on what you told us about how many minutes, on average, you use your cooktop each day and some general assumptions we’ve made about cooktop usage. For example, we’ve assumed you use your cooktop 70% during daylight hours and 30% outside of daylight from October to March, and the reverse from the darker months of April to September (30% day; 70% night).  We’ve also assumed you only use 50% of your cooktop capacity when cooking – see more on capacity in point 2 below.  
2. Cooktop energy consumption: To estimate how much energy it takes to run your cooktop, we use your answers about your current cooktop type (gas or electric, no. of burners).  We assume that your new induction cooktop would have the same number of 'zones' as the burners/zones on your existing cooktop. For electric and induction cooktops, our consumption estimates are based on manufacturer capacity data for selected models.¹⁴   For gas cooktops, our estimates are based on data published by Energy Networks Australia for a -large-size burner.¹⁵  We have also assumed that an induction cooktop reduces cooking time by approx. 50% and 10% compared to gas and electric cooktops respectively (due to improved efficiency).
3. Cost of cooktop energy: To compare how much your old and new cooktops would cost to run, we estimate the price of energy used to run them.  For electric and induction cooktops, we take your electricity rate from 12-1pm for daytime cooking, and from 6-7pm for evening cooking.  If you have an existing gas cooktop, we can’t see your gas rate via the ‘CDR’, so the calculation uses an average rate for your State across AGL customers.  Your actual savings results will vary based on your actual energy prices, and any change in those prices. 

To estimate your carbon savings, we compare the emissions directly associated with the energy used to power each cooktop (existing cooktop vs. new induction cooktop).

• Our emissions estimates use data from the Australian Government's most recent National Greenhouse Accounts (NGA) Factors publication. For electric and induction cooktops powered by electricity, the estimates are based on electricity sourced from the grid at average annual intensity for your state.¹⁶
• The Electrify Now tool only presents carbon emission savings for the 1st year, because the emissions intensity of grid electricity changes over time (and is generally expected to decrease as renewable generation supplies a growing proportion of the grid).

It’s possible that your cooktop result could display a ‘negative’ saving (whether for energy bills and/or carbon emissions).  This can happen if you’ve said you want to switch from your existing electric cooktop to a new induction cooktop, but you select an induction cooktop size which is larger than your current product.  It may take more power to run a larger cooktop, even if it is more energy efficient.¹⁷

 

 

 

If you’ve selected heat pump hot water, you answered some questions about your current type of hot water system and the number of people in your household.  This helped us to estimate:   

• Size of your existing and new system: Where required for our calculations, we have estimated your existing hot water tank size – and new heat pump size - based on the number of people in your house.  To do this, we’ve assumed each member of your household uses 63L of hot water per day (on average).  That usage let’s us roughly estimate the likely current tank size in your house (rather than asking you to check!), and the appropriate size for a new heat pump.  Your actual system size may vary – you should speak to a qualified installer for a personalised recommendation. 
• How much energy it takes to heat water: We calculate how much energy it takes to heat your water from a cold water temperature (estimated for your state) to the temperature at your tap (with an assumed maximum temperature of 50°).  As part of this calculation, we estimate the energy efficiency of each hot water system type (based on a review of manufacturer data and 3rd party studies). These are general estimates – hot water products will vary in performance based on location and usage.  The exact amount of energy used to heat your water depends upon the specific features of your system, how much hot water you use and even when you use it.   

Your annual energy bill savings are estimated by comparing the energy used by your existing hot water system, and your potential new heat pump.  

• For electric storage hot water and heat pump systems, we calculate bill savings by using your electricity rate at 1pm and 1am (split 50/50 between those times). For electric instantaneous systems, we use your rate at 7am and 7pm (being common hot water usage times). If you have an existing gas hot water system, we can’t see your gas rate via the ‘CDR’, so the calculation uses an average rate for your state across AGL customers.
• Your actual savings will vary based on your actual energy prices, any change in those prices, and your hot water usage habits, among other factors.        

The payback period shows the estimated time it would take for your bill savings to equal the upfront cost of your new system.  

• We take an average installation cost for heat pumps from our install partner (excl. financing), minus the approximate value of any applicable rebates.  We then project forward your bill savings, assuming that energy prices will increase at 3% per year.  This is an assumption only – we don’t know what will happen to your energy prices in future, and your actual prices will influence your payback period.

Your carbon savings are estimated by comparing the emissions directly associated with the energy used to power each hot water system (existing system vs. new heat pump). 

• Our emissions estimates use data from the Australian Government National Greenhouse Accounts (NGA) Factors publication. For electric hot water systems powered by electricity, the estimates are based on electricity sourced from the grid at average annual intensity for your state.¹⁸
• The Electrify Now tool only presents carbon emission savings for the 1st year, because the emissions intensity of grid electricity changes over time (and is generally expected to decrease as renewable generation supplies a growing proportion of the grid).