Solar Panel Payback & Savings Calculator
Calculate how quickly your solar panels pay for themselves and your total savings over 25 years. Includes export income from selling surplus energy back to the grid.
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Solar Panels UK Guide 2024
What do I need to know about Annual Solar Generation in the UK?
A 4 kWp solar system generates approximately 3,200-4,400 kWh per year depending on location, roof angle, and shading — enough to cover 40-60% of typical household electricity consumption. Peak output occurs in May-July; December-January generates approximately 5-10% of summer output. Orientation matters: south-facing at 35° from horizontal is optimal. South-west/south-east at 35°: approximately 95% of optimal. East/west-facing: approximately 80% of optimal. North-facing: not recommended (under 50% of optimal output) — a north-facing roof rarely makes financial sense for solar unless it's the only available option and self-consumption (rather than export) is the priority. Flat roofs can use tilted mounting frames to achieve a favourable angle regardless of the roof's own orientation.
What should I know about Smart Export Guarantee (SEG)?
The Smart Export Guarantee replaced the Feed-in Tariff in 2020. Suppliers with over 150,000 customers must offer an export tariff — rates vary significantly. 2024 best rates: Octopus Energy 'Flux' or 'Agile' can exceed 15-30p/kWh during peak demand periods. Minimum SEG rate: suppliers must offer above 0p/kWh — some offer very low rates. Getting the best export rate: use a smart meter (required for SEG), compare SEG tariffs at ofgem.gov.uk, consider battery storage to store excess for evening use, since even a modest SEG payment (often 4-15p/kWh) is usually well below the 25-30p/kWh saved by using that same unit of self-generated electricity instead of buying it back from the grid in the evening.
What's the key thing to understand about Battery Storage?
Solar battery storage (e.g. Tesla Powerwall, Givenergy, SolarEdge) stores daytime solar generation for evening use — when solar panels are not generating but electricity demand is highest. Typical 10 kWh battery cost: £4,000-6,000 (installed). Benefit: a typical household imports 70% of solar generation in summer but only 20-30% with a battery — moving more self-consumption from off-peak export rates to peak rate savings. Battery payback (standalone): 10-15 years in most cases — marginal economics on its own, but the case improves substantially when paired with solar (storing free daytime generation instead of buying overnight electricity at full price) or with a cheap overnight time-of-use tariff, both of which shorten the payback period meaningfully compared with a battery bought in isolation.
Is Solar Worth It in 2026?
With electricity at 24p/kWh and good SEG rates, typical payback is 6-10 years for a 4 kWp system costing £6,000-8,000. System lifetime: 25+ years (panels degrade approximately 0.5% per year). After payback: essentially free electricity for 15+ years. ROI: approximately 8-14% annually in cash terms — better than most savings accounts and comparable to equity market returns, but illiquid. Factors reducing payback: east/west-facing roof, significant shading (trees, chimneys), low electricity consumption during daylight hours (since more of the generated electricity is exported at the lower SEG rate rather than self-consumed at the higher retail-saving rate), and a north-facing or heavily overshadowed roof. Get a site-specific quote and shading assessment before committing — headline payback figures assume a reasonably unobstructed, well-oriented roof.