Solar Panel Calculator
Estimate annual energy output, savings, and payback period for your solar system
Quick answer: A 5kW system in Phoenix, AZ (6.5 peak sun hrs, 80% efficiency) generates about 9,490 kWh/year, saving ~$1,518/yr at 16¢/kWh. At $15,000 install minus 30% ITC = $10,500 net, payback ≈ 7 years.
💡 US ITC 30% federal tax credit
Solar Incentives by Country
| Country | Main incentive | Details |
|---|---|---|
| 🇺🇸 USA | Investment Tax Credit (ITC) | 30% federal tax credit through 2032; state credits additional |
| 🇬🇧 UK | Smart Export Guarantee (SEG) | Suppliers pay for excess energy exported to grid (min 0p, avg 4-8p/kWh) |
| 🇦🇺 Australia | Small-scale Technology Certificates | STC rebate based on location zone; AU$600-900/kW typical |
| 🇩🇪 Germany | EEG Feed-in Tariff | Fixed rate for surplus exported; declining annually |
| 🇯🇵 Japan | FIT surplus buyback | Grid buyback for surplus generation; 8-16 yen/kWh |
| 🇮🇳 India | MNRE Rooftop Scheme | 40% subsidy for first 2kW; 20% up to 3kW (residential) |
| 🇨🇳 China | National subsidy programme | State subsidies and grid buyback; varies by province |
| 🇨🇦 Canada | Provincial programmes | BC, Ontario, Alberta offer rebates; Greener Homes Grant fed. level |
Frequently Asked Questions
What are peak sun hours?
Peak sun hours are a measure of the average daily solar radiation in a location, expressed as hours of sunlight at 1,000 W/m2 (peak intensity). Arizona gets about 6-7 peak sun hours/day; Germany and the UK get 2.5-3.5. A 5kW system in Arizona produces roughly twice the energy of the same system in London.
How long do solar panels last?
Most modern panels are warranted for 25 years and degrade at about 0.5% per year. After 25 years, a typical panel still operates at about 87-90% of original capacity. The inverter usually needs replacement after 10-15 years (cost: $1,000-$3,000).
What is the difference between on-grid and off-grid solar?
On-grid (grid-tied) systems export surplus electricity to the utility grid and draw from it at night. Off-grid systems need battery storage for night-time power. On-grid is more cost-effective in most cases. Hybrid systems combine both, with batteries for backup and grid for the rest.