Solar Feed In Tariff Uk Calculator

Estimate your annual Smart Export Guarantee income, bill savings from self-use, total benefit, and simple payback based on your home solar setup.

Complete Expert Guide: How to Use a Solar Feed in Tariff UK Calculator

If you are searching for a reliable solar feed in tariff UK calculator, you are usually trying to answer one practical question: how much money can your solar panels make or save each year? In the UK, this calculation has changed a lot over the last decade. The original Feed-in Tariff scheme closed to new applicants in 2019, and it was replaced by the Smart Export Guarantee (SEG), where licensed suppliers pay homes and businesses for exported electricity. A modern calculator therefore needs to combine multiple factors: your generation, how much electricity you use at home, what you export to the grid, your SEG unit rate, and your own electricity import tariff.

This page gives you both a working calculator and a professional methodology you can use before requesting quotes. It is designed for homeowners, landlords, and small commercial users who want to compare installations in a structured way. You can run scenarios with and without battery storage, adjust self-consumption, and model panel degradation over time. That gives a much more realistic picture than a simple one-line savings estimate.

Feed-in Tariff vs Smart Export Guarantee in plain language

The historical Feed-in Tariff paid for generation itself and for exported units, often with a deemed export method for small installations. The modern SEG does not pay you for every kWh generated. Instead, suppliers pay for metered exported power. So, in today’s UK market, your total solar value typically comes from two streams:

• Self-consumption savings: every unit of solar you use at home is a unit you do not buy from your supplier.
• Export income (SEG): every unit you export can earn an agreed pence per kWh payment.

Because import unit rates can be materially higher than some SEG rates, increasing daytime usage or adding battery storage can raise total value significantly.

Why a high quality calculator matters before you buy

Good solar financial planning is not only about annual generation. Two homes with identical 4 kWp systems can get very different returns depending on occupancy patterns, electric heating, EV charging habits, and tariff structure. A robust calculator helps you:

1. Benchmark installer quotes against independent financial assumptions.
2. Test realistic best-case and conservative scenarios.
3. Understand whether battery storage improves your payback in your specific pattern.
4. Estimate longer-term benefit, not only first-year benefit.
5. Avoid underestimating the impact of panel degradation and tariff changes.

What inputs drive your result most strongly

1) Annual generation and regional yield

In the UK, generation depends on orientation, pitch, shading, inverter performance, and location. A common planning method uses a regional yield factor in kWh per kWp. For example, a 4 kWp system in a 960 kWh per kWp zone might generate around 3,840 kWh annually before further adjustments. This calculator allows manual generation override so you can enter installer estimates or monitoring data.

2) Self-consumption percentage

Self-consumption can be around 25% to 45% for many homes without batteries, and often higher when batteries are used well. Since imported electricity can be expensive compared with some export rates, this variable is frequently one of the largest financial levers.

3) SEG export rate

SEG rates differ by supplier and tariff design. Some products are flat, others dynamic, and some linked to half-hourly periods. Even a change of a few pence per kWh can alter annual export income noticeably if your exported units are high.

4) Import electricity unit rate

Your bill savings are tied to avoided imports, so this assumption must be realistic. If your import rate rises, the value of self-consumed solar rises too. If it falls, savings drop.

5) Battery effect and degradation

A battery usually raises self-consumption, but it adds upfront capital cost and may involve efficiency losses. Panel degradation is generally modest each year, but over 20 years it can trim cumulative generation enough to influence payback timing.

Reference data table: illustrative UK solar yield by region

Below is an illustrative table used in many early-stage models. Actual output depends on site specifics, but this is a practical baseline for calculator inputs.

Region	Typical annual yield (kWh per kWp)	Estimated output for 4 kWp system (kWh per year)	Comments
South England	980 to 1050	3,920 to 4,200	Often strongest domestic yield range in UK due to irradiance profile.
Midlands and East	930 to 980	3,720 to 3,920	Common planning assumption around 950 to 970 for unshaded systems.
Wales	870 to 940	3,480 to 3,760	Site-level shading and roof geometry can have large impact.
North England	830 to 900	3,320 to 3,600	Still financially attractive in many usage profiles.
Scotland	780 to 850	3,120 to 3,400	Lower yield, but high import prices can preserve strong savings value.

Ranges are indicative for planning only and should be validated with roof-specific design and MCS installer modelling.

Reference data table: SEG and retail rate context

A calculator is only as good as its tariff assumptions. The table below shows typical market ranges used in household planning exercises and why comparing export with import rates is essential.

Metric	Illustrative range	Why it matters in a calculator
SEG export tariff	~2p to 30p+ per kWh (supplier and tariff dependent)	Determines direct cash income from exported electricity.
Domestic import unit rate	Often in the mid-20s p per kWh range in recent capped periods	Drives avoided-cost value of self-consumed solar units.
Typical self-consumption without battery	~25% to 45%	Higher self-use generally increases total annual benefit.
Typical self-consumption with battery	~50% to 80% (usage dependent)	Can shift value from export to import avoidance.

Step by step: how to use this calculator properly

1. Enter system size: use installer proposal size in kWp.
2. Select regional yield: choose the nearest region baseline.
3. Use override if available: if you already have a generation estimate, enter it directly.
4. Set self-consumption: start with your realistic daily pattern. If you work from home, this may be higher.
5. Choose battery yes or no: the tool increases effective self-consumption for scenario testing.
6. Enter SEG and import rates: use current tariff details from your supplier.
7. Add installation cost: include any known extras that are part of your project budget.
8. Set years and degradation: this provides cumulative projection and rough simple payback.
9. Compare scenarios: run at least conservative, expected, and optimistic assumptions.

Interpreting your outputs

Annual generation

This is your year-one estimated production and starting point for all value calculations.

Annual self-use savings

This is usually the largest value component when import electricity is expensive. It is calculated from self-consumed kWh multiplied by your import rate.

Annual export income

This is exported kWh multiplied by your SEG rate. Some households with low daytime usage export a large share and should pay extra attention to tariff choice.

Total annual benefit

This combines self-use savings and export income. It is your first-year headline performance metric.

Simple payback

This divides installation cost by annual benefit. It is useful for comparison, but it is still a simplification because it ignores financing cost, maintenance events, inverter replacement timing, and future tariff volatility.

Common mistakes people make with solar return estimates

• Using very optimistic self-consumption assumptions without checking hourly demand profile.
• Ignoring standing charge and other bill components when comparing outcomes.
• Assuming all export is paid at one premium rate regardless of tariff terms.
• Not checking if battery round-trip efficiency affects net savings assumptions.
• Treating installer generation estimate as guaranteed rather than modeled.

Official UK sources you should review

For policy, market framework, and national statistics, review these authoritative resources:

• Ofgem Smart Export Guarantee guidance
• UK government solar photovoltaic deployment statistics
• UK energy price cap publications

Final expert advice before signing a contract

Use this calculator as a decision framework, then validate each assumption in writing with your installer and supplier. Ask for modeled annual generation, string layout, shading analysis, warranty coverage, and expected performance ratio. If you are considering battery storage, request at least two scenarios: one with your current demand pattern and one with planned behavior changes like EV charging or heat pump scheduling.

When comparing quotes, focus on lifetime value and risk, not only headline panel wattage. A system that looks cheaper initially may provide weaker export terms, lower forecast generation, or less robust equipment support. Keep your assumptions transparent, store your scenario runs, and update figures each time tariffs change. A careful calculator-based approach is one of the strongest ways to improve your long-term return from UK rooftop solar.

In short, the best solar feed in tariff UK calculator is not just a number generator. It is a planning tool that combines policy reality, tariff structure, and household behavior. If you use it methodically, you can move from guesswork to evidence-based decisions and choose a system configuration that matches your budget, risk tolerance, and energy goals.