Enter your energy details to discover your savings potential, payback period, and lifetime return on investment.
Your Energy Profile
Breakdown
Estimates based on regional sun hours, standard system costs, and government rebate figures. Results are indicative. Consult a certified installer for a tailored quote.
Solar 101
Understanding the numbers behind your investment helps you make a smarter, more confident decision.
Every solar system produces energy based on two things: its size in kilowatts (kW) and the average daily sunlight hours in your area — called Peak Sun Hours (PSH). A 6.6 kW system in Queensland (5.2 PSH) generates roughly 26–28 kWh per day, while the same system in Victoria (4.0 PSH) produces closer to 20–22 kWh. Multiply daily output by 365 to get your annual generation figure — the foundation of every savings calculation.
Savings come from two streams. Self-consumption: every kWh your panels generate that you use directly avoids a grid purchase at your full retail rate (28–35¢/kWh). Feed-in tariff (FiT): surplus electricity exported to the grid earns a credit, usually 5–12¢/kWh. Homes that use more power during daylight hours — with pool pumps, dishwashers, or EV charging — see significantly higher self-consumption rates and therefore larger savings.
A typical residential system in Australia costs $900–$1,200 per installed kW before incentives. The federal government's Small-scale Technology Certificates (STCs) reduce upfront costs substantially — often by $2,000–$5,000 depending on system size and location. Some states layer additional rebates on top. Always calculate your net cost after all applicable rebates before dividing by annual savings.
Payback period is simply your net system cost ÷ annual savings. If your system costs $6,000 after rebates and saves $1,500 per year, your payback is 4 years. Australian homeowners typically see payback in 3–7 years. Critically, a quality solar system is warrantied for 25 years — meaning 18–22 years of near-free electricity after breakeven.
Return on investment measures the total profit of your solar system relative to its cost over its full lifespan. The formula is: (Total Lifetime Savings − Net Cost) ÷ Net Cost × 100. A typical household with a 6.6 kW system saving $1,800/year accumulates roughly $45,000 in savings over 25 years on a $6,000–$8,000 net investment — an ROI of 460–650%. That outperforms most term deposits, managed funds, and many share market returns over the same period. When you also factor in electricity price escalation (historically 3–5% per year), the actual future value of savings is even higher than a flat calculation suggests.
Adding a battery (like a Tesla Powerwall or BYD Battery Box) changes the ROI equation significantly. Batteries store excess solar for use at night, further reducing grid purchases. However, they add $8,000–$15,000 to system cost, with a standalone payback of 8–14 years. Batteries make the most financial sense in homes with high evening electricity use, those on time-of-use tariffs with expensive peak rates, or households wanting energy independence during outages. Our calculator models panel-only systems; battery ROI depends heavily on individual usage patterns and warrants a separate analysis.
Financial return is only part of the story. A 6.6 kW solar system offsets approximately 8–10 tonnes of CO₂ per year — equivalent to taking two cars off the road. Over 25 years, a single household installation can prevent 200+ tonnes of carbon emissions. Going solar also provides energy price certainty: rather than absorbing annual retailer price hikes, you lock in a large share of your electricity at effectively zero marginal cost. That stability has real-world value that goes beyond any spreadsheet.
Whether you're motivated by savings, sustainability, or security — the right solar system, sized correctly for your roof and usage, is one of the highest-returning home investments available today. Use this calculator as a starting point, then engage a Clean Energy Council-accredited installer for a site-specific assessment.
Our Story
Built by energy enthusiasts, for everyday homeowners ready to take control of their electricity bills.
We were frustrated. Every solar quote we received came with a glossy brochure, a pushy sales pitch, and numbers that seemed to change depending on who was in the room. We wanted a simple, transparent, jargon-free way to understand whether solar actually made financial sense — before ever picking up the phone to a salesperson.
SolarCalc was born from that frustration. We built a tool that puts the numbers first: real sun-hour data by region, realistic system cost estimates, and government rebate figures that are kept up to date. No email capture required. No sales funnel. Just honest maths.
Our model uses publicly available Peak Sun Hours (PSH) data from the Australian Renewable Energy Agency (ARENA) and the US National Renewable Energy Laboratory (NREL), combined with current average installed system costs and feed-in tariff rates by state. We apply a conservative 78% performance efficiency factor to account for real-world losses from heat, shading, inverter efficiency, and panel degradation over time.
SolarCalc is independent. We are not affiliated with any solar retailer, installer, or manufacturer. We earn no referral fees or commissions. Our only goal is to help you understand the numbers clearly so you can make a confident, informed decision. We recommend always obtaining at least three quotes from Clean Energy Council-accredited installers before committing to a system.
While we strive for accuracy, solar ROI is inherently variable. Actual results depend on your specific roof orientation, shading, panel quality, inverter brand, installer workmanship, household usage patterns, and future electricity tariff movements. This calculator provides indicative estimates for planning purposes only and should not be relied upon as financial advice.
Want to collaborate or provide feedback? We're always looking to improve our model with better data. If you're a researcher, energy economist, or industry professional with data to contribute, we'd love to hear from you. Get in touch →
Legal
Last updated: April 2025. We keep this short because we genuinely don't collect much.
SolarCalc is a client-side calculator. All calculations happen entirely in your browser — your electricity bill, location, and system inputs are never transmitted to our servers or stored outside your device. When you use the Contact form, we collect only your name, email address, and the message you choose to send. We collect no other personal information.
Contact form submissions are used solely to respond to your enquiry. We do not add you to any mailing list, sell your contact details, or share your information with third parties without explicit consent. We will never send you unsolicited marketing communications.
SolarCalc uses minimal, privacy-respecting analytics (page view counts only) to understand how the tool is used and improve it over time. We do not use advertising cookies, tracking pixels, or third-party behavioural analytics. We do not serve ads. We do not use Google Analytics or Facebook Pixel.
Calculator inputs exist only in your browser's memory and are discarded when you close or refresh the page. Contact form data is transmitted over encrypted HTTPS and stored securely. We retain contact enquiries for up to 12 months, after which they are permanently deleted.
SolarCalc loads Google Fonts (for typography) and the Tailwind CSS CDN (for styling). These services may log your IP address in accordance with their own privacy policies. We have no control over their data practices. We recommend reviewing Google's Privacy Policy if this concerns you.
You have the right to request access to any personal data we hold, request its correction or deletion, and withdraw any consent previously given. To exercise these rights, contact us via the Contact page. We will respond within 30 days.
SolarCalc is not directed at children under 13. We do not knowingly collect personal information from children. If you believe a child has provided us with personal data, please contact us immediately and we will delete it promptly.
We built SolarCalc because we believe in transparency. That same ethos applies to your data. We will never monetise your personal information. We will never sell your data. We will always be straightforward about what we collect and why. If this policy ever changes materially, we'll update the "Last updated" date above and note what changed.
Questions about this policy? Contact us →
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Common Questions
Our calculator uses regional averages. An installer will assess your specific roof pitch, orientation, shading from trees or nearby structures, and local network tariffs — all of which affect real-world output. Treat our results as a planning benchmark, not a final quote.
Our model is calibrated for residential systems up to 20 kW. Commercial systems involve different network tariff structures, depreciation schedules, and GST implications that require a specialist commercial solar assessment.
We review sun-hour data annually and update system cost and rebate figures quarterly as market conditions change. If you spot data that appears outdated, please use the contact form to let us know.