Most advice about home energy upgrades boils down to "get solar." That's fine as far as it goes, but it ignores the fact that there are half a dozen other upgrades that can pay for themselves, and the order you do them in genuinely matters.
Each upgrade changes your energy baseline. Install solar first, and your electricity bill drops, which changes how much you save from every upgrade after it. Switch off gas entirely, and you eliminate the daily supply charge on top of the usage savings. The right first move depends on where you live, what energy you use, and what you are paying for it.
We ran our calculator for a typical 3-bedroom home in every Australian capital to see how the optimal sequence differs. Five of the seven capitals are gas-connected; Brisbane and the warm parts of QLD are modelled as electric-only because most homes there no longer have a gas service. All savings are in nominal dollars. All profit figures are in today's dollars over 15 years (meaning future savings are discounted so a dollar saved in year 10 counts for less than a dollar saved today). A positive profit means the upgrade beats an 8% annual return.
These numbers assume your appliances and car are at end of life
Every upgrade in these sequences assumes you are replacing something that is due for replacement anyway. The cost shown is the full price of the electric alternative, not an additional spend on top of a working appliance.
If your gas hot water system is 2 years old, do not rip it out to install a heat pump. If your car is 3 years old, do not sell it to buy an EV. The economics only work when you are comparing the electric option against buying another gas or petrol replacement at the point where your current one needs replacing.
The calculator lets you specify the age of each appliance and your car. When you do, it delays that upgrade to the natural replacement point and adjusts the profit figures accordingly, including removing any rebates that may have expired by then. If you leave the age fields blank, the calculator assumes everything is at end of life. That is what the numbers below show: the best case, where every switch happens at the natural replacement point.
Sydney: Solar first, then heat pump, then EV
- Solar + Battery ($18,185 cost, $59,143 savings). $11,374 profit in today's $
- Heat Pump Hot Water ($2,975 cost, $11,567 savings). $2,497 profit in today's $
- Electric Vehicle ($9,000 cost, $23,891 savings). $4,636 profit in today's $
- Induction Cooktop ($1,400 cost, $8,660 savings). $2,698 profit in today's $
- Draught Sealing ($200 cost, $652 savings). $186 profit in today's $
Total investment: $31,760. Total savings: $103,912. Profit in today's dollars: $21,391.
Sydney has high electricity rates (36c/kWh) and good sun, so solar delivers the biggest absolute return by a wide margin. A heat pump hot water system is the second-strongest move, helped by NSW Energy Savings Scheme (ESS) rebates. After that, the EV and the remaining gas switches round out the plan. Insulation does not make the cut here; the calculator's greedy ranking puts it below the 8% benchmark in a Sydney climate.
Melbourne: EV first, then solar, then the gas switches
- Electric Vehicle ($9,000 cost, $15,053 savings). $379 profit in today's $
- Solar + Battery ($17,853 cost, $37,748 savings). $1,005 profit in today's $
- Heat Pump Hot Water ($2,915 cost, $10,954 savings). $2,268 profit in today's $
- Reverse Cycle Heating ($2,470 cost, $21,481 savings). $7,690 profit in today's $
- Induction Cooktop ($1,660 cost, $8,776 savings). $2,486 profit in today's $
Total investment: $33,898. Total savings: $94,012. Profit in today's dollars: $13,829.
Melbourne is more nuanced than Sydney. Lower electricity rates (29c/kWh) and less sun mean solar alone is a marginal call, but a properly sized solar plus battery system is now back in the mix as a positive-NPV step. The high gas usage profile (cold winters, widespread gas heating) is what really shifts the order: reverse cycle heating delivers the largest single profit thanks to Victorian Energy Upgrade rebates, and completing the gas disconnection sequence (heat pump hot water, induction cooktop) eliminates the daily supply charge on top of the usage savings. The EV ranks first because it is a large recurring petrol bill replaced by very cheap kilometres; once it is in the plan, adding solar to soak up that extra electrical load makes the panels-and-battery step worthwhile.
Brisbane: Solar dominates, no gas to switch
- Solar + Battery ($20,018 cost, $55,809 savings). $7,895 profit in today's $
- Electric Vehicle ($9,000 cost, $23,891 savings). $4,636 profit in today's $
- Heat Pump Hot Water ($1,530 cost, $7,508 savings). $2,080 profit in today's $
Total investment: $30,548. Total savings: $87,208. Profit in today's dollars: $14,611.
We model the typical Brisbane household as electric-only: most QLD homes have an electric (often resistive) hot water system rather than gas, and very few have gas heating, so the calculator treats Brisbane as having no gas service. That means no gas-switch upgrades and no induction-cooktop step, but a heat pump hot water upgrade still pays back quickly because it replaces a high-running-cost electric resistive system. Excellent sun makes solar the clear winner; the EV is the second move. If your Brisbane home does have gas, the order will be different. Run the calculator with your actual setup.
Adelaide: The best returns in the country
- Solar + Battery ($19,118 cost, $74,229 savings). $17,988 profit in today's $
- Heat Pump Hot Water ($3,175 cost, $13,680 savings). $3,296 profit in today's $
- Electric Vehicle ($9,000 cost, $23,523 savings). $4,458 profit in today's $
- Induction Cooktop ($1,500 cost, $10,574 savings). $3,504 profit in today's $
- Draught Sealing ($600 cost, $1,374 savings). $134 profit in today's $
Total investment: $33,393. Total savings: $123,381. Profit in today's dollars: $29,381.
SA has the highest electricity rates in the country (43c/kWh), which makes every kilowatt-hour you save or generate worth more. Solar plus battery alone clears $17,000 of profit in today's dollars. Even draught sealing scrapes past the 8% benchmark here, although insulation does not quite make it on this household.
Perth: Strong solar, simple plan
- Solar + Battery ($15,783 cost, $44,564 savings). $6,537 profit in today's $
- Electric Vehicle ($9,000 cost, $24,628 savings). $4,990 profit in today's $
- Heat Pump Hot Water ($3,525 cost, $10,438 savings). $1,414 profit in today's $
- Induction Cooktop ($1,800 cost, $5,254 savings). $686 profit in today's $
Total investment: $30,108. Total savings: $84,884. Profit in today's dollars: $13,628.
Perth gets excellent sun and a relatively low gas usage profile, which means solar and the EV do most of the heavy lifting. The gas switches still clear the benchmark but contribute much less to the total than they do in Melbourne or Hobart. Insulation and draught sealing fall outside the recommended set here.
Hobart: High feed-in tariff puts solar back on top
- Solar + Battery ($13,364 cost, $31,167 savings). $2,273 profit in today's $
- Electric Vehicle ($9,000 cost, $22,492 savings). $3,962 profit in today's $
- Draught Sealing ($600 cost, $1,826 savings). $328 profit in today's $
- Insulation ($2,100 cost, $4,558 savings). $58 profit in today's $
- Heat Pump Hot Water ($3,915 cost, $8,326 savings). $18 profit in today's $
Total investment: $28,979. Total savings: $68,368. Profit in today's dollars: $6,639.
Tasmania has lower electricity rates (27c/kWh) and less sun than the mainland capitals, but it also has the highest regulated feed-in tariff in the country (8.8c/kWh), which makes solar exports unusually valuable. A correctly sized solar plus battery system is the strongest opening move for this household, with the EV close behind because every kilometre runs on cheap home-generated electricity. After that, the cool-climate shell upgrades (draught sealing, insulation) earn their place because they cut a very large heating bill. Reverse cycle heating does not clear the 8% benchmark for this household without state rebates, and induction cooktop comes back negative on a small gas-usage profile; if you qualify for a future TasNetworks or federal scheme that lowers the upfront on those switches, the picture changes. Run your own numbers in the calculator if you have firm rebate eligibility to plug in.
Canberra: ACT incentives change the game
- Solar + Battery ($9,633 cost, $34,477 savings). $7,602 profit in today's $
- Electric Vehicle ($7,200 cost, $23,891 savings). $6,436 profit in today's $
- Heat Pump Hot Water ($3,015 cost, $7,941 savings). $740 profit in today's $
- Induction Cooktop ($1,200 cost, $1,165 savings). -$651 profit in today's $
- Reverse Cycle Heating ($1,640 cost, $9,328 savings). $2,651 profit in today's $
- Insulation ($1,680 cost, $5,360 savings). $860 profit in today's $
- Draught Sealing ($480 cost, $1,694 savings). $386 profit in today's $
Total investment: $24,848. Total savings: $83,856. Profit in today's dollars: $18,024.
The ACT's Sustainable Household Scheme provides low-interest loans and direct support that reduce the effective cost of most upgrades. The EV is particularly cheap here ($7,200 vs $9,000 elsewhere) due to ACT-specific incentives, and reverse cycle heating comes in at a low net cost thanks to the same scheme. The induction cooktop step is the outlier: in this household it is included to complete the gas-disconnection and shed the daily supply charge, but the cooktop on its own does not clear the 8% benchmark (low gas cooking usage means the savings are too small for the upfront). Cold winters make insulation and draught sealing worthwhile here in a way that they aren't in most other capitals.
Why the order matters
The key insight is that each upgrade changes the baseline for every upgrade that follows. Some examples:
Solar reduces your electricity cost, which means upgrades that add electrical load (heat pump, induction cooktop) save less per kWh after solar is installed. But solar also means some of that new load is covered by your own panels rather than the grid.
Switching off gas appliances one by one does not eliminate your gas supply charge. The calculator's daily supply charge ranges from 83c in the ACT to $1.20 in Brisbane (where it's a moot point because there's no gas connection in the model). You only stop paying that charge when the last gas appliance is replaced and the meter is disconnected. The calculator bundles the gas switches together when evaluating each step so the value of completing the set is reflected in the ranking.
Insulation reduces heating and cooling load, which affects both the solar self-consumption calculation and the savings from a reverse cycle upgrade. In warmer capitals it doesn't move the needle enough to clear the benchmark, but in Hobart and Canberra it earns a place in the recommended set.
If you did Melbourne's upgrades in Sydney's order, you would leave money on the table because you would be optimising for solar in a city where gas switching is doing most of the work.
Incentive expiry is factored in
If an upgrade gets delayed (saving up for it, or waiting for your car to reach end of life), the calculator checks whether rebates will still be available at the future purchase date. Federal STC deeming years reduce annually until the scheme ends in 2030, and state programs like VIC Solar Homes have their own expiry dates. The numbers already account for this.
Run your own numbers
The figures above are for a typical 3-bedroom home. Your situation will vary depending on your postcode, energy rates, and which appliances you have. The calculator evaluates every upgrade, works out the optimal sequence, and shows you the profit-maximising plan for your home.
Where these numbers come from
Electricity and gas rates from AER monitoring reports and published retailer tariffs. Equipment costs from SolarChoice and installer surveys. STC values from the Clean Energy Regulator. State incentive details from published government programs. Full data source list on the data sources page.