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WattMateWattMate

Western Australia's solar and battery platform. Free and independent.

Fighting dodgy deals and bill shock, one rooftop at a time.

0459 742 134
admin@wattmate.com.au

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Supporting members of the Clean Energy Council
WattBot, WattMate's bill and tariff explainer — a WattForce brand character
Explained by WattBot, WattMate's bill and tariff explainer
About WattForce expertsAn illustrated WattMate expert persona — a brand character voicing our team's real WA solar experience, not a real person.

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Scan appliances with your camera, upload your bills, and get personalised savings recommendations

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Browse every CEC-approved home battery, inverter and solar panel available in WA

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Water heater calculator
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Water heater calculator

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Independent — installers pay us a flat referral fee, never a percentage of your price. We match you with accreditation-checked WA installers and review installer accreditation as part of onboarding.

Get free quotesBuild my full energy plan

25-year solar ROI projection

A WA estimate that includes 0.5% annual panel degradation and 2% yearly electricity price rises.

$8,500
$2,200/yr
Payback

4 yrs

25-year savings

$66,053

Total ROI

677%

1
$2,200
2
$4,433
3
$6,699
4
$8,999
5
$11,333
6
$13,702
7
$16,106
8
$18,546
9
$21,022
10
$23,535
11
$26,086
12
$28,675
13
$31,302
14
$33,968
15
$36,674
16
$39,420
17
$42,207
18
$45,036
19
$47,907
20
$50,821
21
$53,778
22
$56,779
23
$59,825
24
$62,916
25
$66,053
Before payback After payback System cost
Net profit: $57,553

Water heater upgrade calculator

Compare water heating systems with Synergy (WA) energy rates and rebates

Efficiency: 90%

Efficiency: 320%

Daily usage: 200L hot water

Average: $0.025-0.035/MJ

Current annual cost

$1411.87

Electric Storage Tank • 11.6 kWh/day

New annual cost

$397.09

Heat Pump (Air Source) • 3.3 kWh/day

Annual savings

$1014.78

72% reduction

Payback period

4.4years

Net cost: $4500

10-year net savings

$5647.82

After installation costs and rebates

Environmental impact
Annual energy reduction

3051kWh

72% less energy

CO₂ emissions saved

2044kg/yr

≈ 94.0 trees worth

System recommendations
  • Heat Pumps are 3x more efficient than electric tanks. Best for most Australian climates, with federal STCs currently worth about $918 off the install.
  • Solar hot water systems are ideal in sunny areas (QLD, WA, NT) with up to $1,500 in rebates.
  • Gas instantaneous systems work well for smaller households (1-2 people) with lower upfront costs.
  • Size matters: 315L for 4 people, 400L for 5-6 people. Oversized systems waste energy, undersized ones run out.
  • Pair with solar panels to maximise savings — heat water during the day with free solar energy.
Estimates only — not financial advice

This calculator provides estimates only and does not constitute financial, tax, or legal advice. Actual savings, payback periods, and rebate amounts depend on your specific usage, solar generation, electricity plan, and the WA Battery Scheme/STC rules current at the time of purchase — figures shown here may not reflect current rates.

Consult a licensed installer, financial adviser, or your electricity retailer before making a purchase decision. WattMate is not responsible for financial decisions made based on these estimates.

Assumptions

  • Hot water usage: 50 L per person per day, heated 15°C → 60°C (0.001163 kWh per L·°C)
  • System efficiencies: electric tank 90%, gas tank 65%, heat pump 320%, solar+boost 400%, gas instant 85%
  • Synergy A1 (WA) electricity rate default: 0.3326 $/kWh
  • Emissions: grid 0.67 kg CO₂/kWh; gas 0.0512 kg CO₂/MJ

Generated by WattMate Energy Hub. Estimates only — final figures depend on system + tariff details.

Energy calculators for WA homes | WattMate