Question 1

What is the Smart Export Guarantee (SEG) and how much does it pay?

Accepted Answer

The Smart Export Guarantee requires licensed energy suppliers with 150,000+ customers to offer export tariffs to eligible generators with solar, wind or other small-scale renewables. Rates vary by supplier — typical SEG rates in 2025 range from 5p to 15p per kWh exported, with some fixed tariffs up to 24p (Octopus Outgoing Fixed). You must have a smart meter to receive SEG payments.

Question 2

How much electricity does a 4kWp solar system generate in the UK?

Accepted Answer

A typical 4kWp system generates approximately 3,200–4,200 kWh per year depending on location. South-facing panels in the South East can achieve 1,050 kWh per kWp annually, while Scotland may achieve only 850 kWh/kWp. This calculator uses region-specific yield factors from 850 to 1,050 kWh/kWp/yr.

Question 3

Can businesses claim VAT relief on solar panels?

Accepted Answer

Yes — from April 2022, solar panel installations for residential properties attracted 0% VAT (down from 5%), extended to April 2027. Commercial installations are generally standard-rated at 20% VAT, though businesses that are VAT-registered can reclaim input VAT. The ECO4 scheme (for eligible households) and the Great British Insulation Scheme (GBIS) can provide grants for energy efficiency measures including insulation, but not solar panels directly.

Question 4

What is the typical payback period for solar panels in the UK?

Accepted Answer

For a residential 4kWp system costing around £7,000–£9,000, payback is typically 8–12 years depending on energy usage patterns, export tariff and location. Commercial systems with higher self-consumption rates (50–70% vs 30% for homes) can achieve 6–9 year payback periods. Panel manufacturers typically guarantee 80% output at 25 years.

Question 5

How much CO₂ do solar panels save per year?

Accepted Answer

Using the BEIS 2024 UK grid emission factor of 0.207 kgCO₂e per kWh, a 4kWp system generating 3,500 kWh/yr displaces approximately 0.73 tCO₂e per year from grid electricity. Over 25 years this totals around 18 tCO₂e, equivalent to roughly 3 return flights London–New York.

Region	Annual yield (kWh/kWp)	4kWp system output
London	1,000	~4,000 kWh/yr
South East	1,050	~4,200 kWh/yr
Midlands	950	~3,800 kWh/yr
North England	900	~3,600 kWh/yr
Scotland	850	~3,400 kWh/yr

Solar Panel ROI Calculator — UK 2025

Solar Panel ROI Calculator

UK solar yield by region (kWh per kWp per year)

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