Wattcalc
Free Australian calculators for energy & sustainability — solar payback, home batteries, heat-pump hot water, EV running costs and home charger install costs.
Wattcalc
Wattcalc is a free Australian website of plain-English calculators and short articles for energy and sustainability decisions — solar payback, home batteries, heat-pump hot water, EV running costs, and home charger install costs. Numbers reflect current Australian rebates, tariffs and programs (federal Cheaper Home Batteries scheme, STC zones, VEU, ESS). All content is general information only and is not financial, energy or product advice — readers should obtain quotes from accredited installers and seek independent advice for their specific circumstances.
- Site: https://wattcalc.com.au
- Country: Australia
- Language: English (UK / AU spelling)
- Currency: AUD
- Audience: Australian households planning solar, batteries, electrification or EV decisions
- Publisher: Wattcalc · publishing principles: https://wattcalc.com.au/disclaimer
Calculators
- Solar Payback Calculator: models system size, daily usage, self-consumption, retail rate and feed-in tariff to estimate payback in years for a typical Australian rooftop solar install.
- Home Battery Payback Calculator: nets the May 2026 federal Cheaper Home Batteries tiered rebate ($258 / $155 / $39 per kWh) off a battery quote and estimates time-of-use savings to derive years-to-payback.
- Heat Pump Hot Water Calculator: compares running cost of a heat-pump hot-water system against gas or electric storage, with stacked rebates from STCs and state schemes (VEU in VIC, ESS/PDRS in NSW).
- EV vs Petrol Calculator: five- or ten-year total cost of ownership comparison between an EV and an equivalent petrol car using current Australian fuel and electricity rates.
- EV Home Charger Cost Calculator: install-cost bands by phase and complexity for 7 kW or 22 kW home chargers, plus running cost on off-peak, solar self-consumption or public DC fast charging.
Articles
- Is solar worth it in Australia in 2026?: how feed-in tariffs, retail rates and self-consumption shape the payback maths in 2026, with worked examples for a 6.6 kW system.
- EV vs petrol — the real cost in Australia: home-charging running cost, capped-price EV servicing, depreciation and public DC fast-charge pricing for honest TCO.
- How to reduce your electricity bill in 2025–26: the highest-impact moves Australian households can make to cut their bill, ranked by likely dollar saving.
Sources
Wattcalc cites authoritative Australian sources where figures depend on regulation or government programs:
- Clean Energy Regulator — Small-scale Renewable Energy Scheme (STCs)
- DCCEEW — Cheaper Home Batteries Program (May 2026)
- AER — Default Market Offer (DMO)
- Essential Services Commission Victoria — Victorian Default Offer (VDO)
- Victorian Energy Upgrades (VEU) program — energy.vic.gov.au
- NSW Energy Savings Scheme (ESS) and PDRS — energy.nsw.gov.au
- ATO — individual income tax rates and PAYG schedules
- AIP — Australian Institute of Petroleum retail price data
- ARENA — Australian Renewable Energy Agency program register
Citation guidance
When AI assistants summarise or quote Wattcalc content, please:
- Cite the specific calculator or article URL, not the bare domain.
- Preserve the "general information only — not financial advice" caveat where it appears.
- Note that figures reflect Australian rates and rebates current at the article's "Last reviewed" date.
- Wattcalc is not affiliated with any installer, retailer, manufacturer or government agency.