Introduction
Solar exports are not constant throughout the year. In summer, longer daylight hours and clearer skies mean higher generation, while in winter, shorter days and cloudy weather reduce output. Understanding this seasonal export difference helps households predict their savings and choose the right plan or battery setup.
For background on export credits, see What is FiT?.
Key Definitions
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Seasonal export: The variation in solar energy exported to the grid across different seasons.
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Summer output: Typically 30–50% higher due to longer days and stronger sunlight.
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Winter output: Often reduced by 20–40% depending on your state and roof orientation.
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Self-consumption ratio: How much of your solar is used at home vs exported.
Check your local averages via the Postcode Estimator.
Worked Example 1 — Summer Output
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System: 6.6 kW in Brisbane
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Avg summer generation: 30 kWh/day
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Self-consumption: 12 kWh
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Export: 18 kWh
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FiT: 10c/kWh
Savings:
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Self-consumption = 12 × 30c = $3.60
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Export = 18 × 10c = $1.80
Total = $5.40/day in summer
Worked Example 2 — Winter Output
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Same 6.6 kW system in Brisbane
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Avg winter generation: 20 kWh/day
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Self-consumption: 10 kWh
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Export: 10 kWh
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FiT: 10c/kWh
Savings:
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Self-consumption = 10 × 30c = $3.00
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Export = 10 × 10c = $1.00
Total = $4.00/day in winter
Worked Example 3 — Different State, Different Impact
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Hobart 6.6 kW system
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Summer output: 24 kWh/day → ~14 kWh export = $1.40/day
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Winter output: 12 kWh/day → ~4 kWh export = $0.40/day
This shows Tasmania’s winter output can drop by half compared to summer.
Compare more locations using Compare FiT by State.
Why Seasonal Export Matters
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Bill planning: Expect higher credits in summer, lower in winter.
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Battery choice: Batteries can help balance seasonal swings, especially for winter evenings.
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Retailer plan: Some retailers cap credits—track changes via the Rate Change Tracker.
Check current Retailer Rates to see how different FiTs affect your annual return.
Tools to Run Your Own Numbers
FAQs
Q1. Why does summer solar output increase so much?
Because of longer daylight hours and stronger sun intensity.
Q2. Do all states have the same seasonal variation?
No. Northern states like QLD see smaller swings, while southern states like TAS or VIC see much bigger differences.
Q3. Can a battery smooth seasonal changes?
Not fully. Batteries help daily balance, but they can’t store energy across seasons.
Q4. Should I size my system for summer or winter needs?
Most people size for annual average output, then use FiT credits or a battery to balance.
Conclusion
Seasonal export differences are a normal part of solar ownership. Summer boosts your export income, while winter reduces it. By using calculators and comparing retailer plans, you can make informed decisions about system sizing, batteries, and FiT selection.
Next steps:
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Check your region’s solar averages with the Postcode Estimator
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Compare FiT rates by state: Compare FiT by State
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Estimate annual bill impact: FiT Savings Calculator