MCS Certified
Microgeneration Certification Scheme
NAPIT Approved
Electrical Competency
RECC Member
Consumer Protection
ISO 45001
Health & Safety Management
ISO 9001
Quality Management
ISO 14001
Environmental Management
4.9 / 5
500+ verified reviews
Commercial Solar ROI Calculator
Estimate the financial returns of a commercial solar panel installation for your business. Adjust the inputs below to see your projected savings, payback period, and 25-year returns instantly.
This calculator provides indicative estimates based on average UK data. For a precise, site-specific financial projection, book a free site survey with our team. See our full cost guide for detailed pricing breakdowns.
Your Details
Your Estimated Returns
Estimated System Cost
£95,000
Tax Saving (AIA)
£23,750
Effective Cost After Tax
£71,250
Annual Generation
90,000 kWh
Annual Self-Consumption Savings
£12,960
Annual Export Income
£2,880
Total Annual Benefit
£15,840
Payback Period
4.5 yrs
25-Year Net Benefit
£324,750
Savings Breakdown
Annual CO2 Reduction
18.6 tonnes
Equivalent Trees Planted
932
25-Year Cumulative Returns
Payback Timeline
Get Your Full Report
Enter your email to receive a detailed PDF breakdown of these projections.
Ready for an Accurate Quote?
This calculator provides indicative estimates. Your actual costs and savings depend on your specific building, location, roof type, and energy consumption patterns. Our free site survey delivers a precise, tailored financial projection for your business.
Book Free Site SurveyHow the Calculator Works
Our commercial solar ROI calculator uses industry-standard assumptions to estimate your financial returns. Understanding these assumptions helps you interpret the results and identify where your actual returns might differ from the estimates shown.
System Cost
The calculator uses an average installed cost of £950 per kW across all system sizes. In practice, larger systems cost less per kW due to economies of scale. A detailed breakdown of costs by system size is available in our commercial solar cost guide. Your actual quote will be based on a site-specific assessment and may be higher or lower than this average.
Annual Generation
We assume annual generation of 900 kWh per kW of installed capacity, which is a conservative estimate for the South East of England. Well-oriented systems in Essex typically generate 900-1,000 kWh/kWp/year. Systems with sub-optimal orientation or partial shading may generate slightly less. Our site survey includes detailed shading analysis and generation modelling to provide an accurate forecast.
Self-Consumption Savings
Self-consumption savings are calculated by multiplying the electricity you use directly from the solar panels by the avoided grid electricity cost of £0.24/kWh. This represents a typical commercial electricity rate in 2026. Businesses on higher tariffs will see greater savings, while those on lower rates will see proportionally reduced returns. Your actual tariff can vary significantly depending on your contract and consumption volume.
Export Income
Electricity not consumed on-site is exported to the grid under the Smart Export Guarantee (SEG). The calculator uses a conservative rate of £0.08/kWh. Actual SEG rates vary by supplier and tariff. Maximising self-consumption is always more financially beneficial than exporting, as the self-consumption saving is approximately three times the export rate.
Corporation Tax Relief
When the corporation tax toggle is set to "Yes," the calculator applies the Annual Investment Allowance (AIA), which allows 100% of the system cost to be deducted from taxable profits. At the current 25% corporation tax rate, this reduces the effective system cost by 25%. For detailed guidance on claiming capital allowances, see our capital allowances guide.
Payback and Lifetime Returns
The payback period divides the effective cost (after tax relief) by the total annual benefit. The 25-year net benefit multiplies the annual benefit by 25 years and subtracts the effective cost. These figures do not account for electricity price inflation, panel degradation, maintenance costs, or inverter replacement. In practice, electricity price increases tend to more than offset degradation and maintenance, meaning actual returns typically exceed the calculator estimates over the system lifetime.
Disclaimer: This calculator provides indicative estimates for informational purposes only. Results are based on simplified assumptions and average data. Actual installation costs, energy generation, savings, and returns will vary depending on site-specific factors including location, roof orientation, shading, structural condition, electrical infrastructure, energy consumption patterns, and prevailing electricity tariffs. Tax advice is general in nature and should be verified with a qualified accountant. EC Eco Energy accepts no liability for decisions made based on calculator results. For an accurate financial assessment, please request a formal quotation following a site survey.
Frequently Asked Questions
This calculator provides a reliable indicative estimate based on average UK solar generation data (900 kWh/kWp/year), current electricity rates, and standard installation costs. Actual results will vary depending on your specific location, roof orientation, shading, electricity tariff, and consumption patterns. For a precise financial projection tailored to your business, we recommend booking a free site survey with our team.
Self-consumption rate depends on how much of the solar electricity your business uses directly rather than exporting to the grid. Businesses operating Monday to Friday during daylight hours typically achieve 50-70% self-consumption. Businesses with 24/7 operations like manufacturing facilities or cold storage may achieve 70-90%. Businesses with low daytime usage or weekend closures may see 30-50%. Adding battery storage can increase self-consumption by 15-25%.
When you purchase a commercial solar system, you can deduct the full cost from your taxable profits using the Annual Investment Allowance (AIA), up to £1 million. At the current 25% corporation tax rate, this means a tax saving equal to 25% of the system cost. This effectively reduces the amount you pay for the system, shortening the payback period significantly. This benefit only applies to businesses paying corporation tax who purchase the system outright.
Larger commercial solar systems benefit from economies of scale, meaning the cost per kW decreases as system size increases. While this calculator uses an average cost of £950/kW across all sizes, in reality a 250kW system costs significantly less per kW than a 30kW system. When you request a site-specific quote, the payback period for larger systems will typically be even shorter than shown here.
The Smart Export Guarantee (SEG) requires licensed electricity suppliers to offer payment for exported solar electricity. This calculator uses £0.08/kWh as a conservative estimate. Actual SEG rates vary by supplier and can range from £0.03 to £0.15/kWh. Some suppliers offer higher rates for businesses that can provide export at predictable times. We can help you identify the best SEG tariff for your installation.
The 25-year benefit figure in this calculator is based on current electricity prices held constant over 25 years. In reality, electricity prices have historically increased by 3-5% per year, meaning your actual savings over 25 years could be significantly higher than the estimate shown. This makes the calculator a conservative projection of your true returns.
Ready to Cut Your Business Energy Costs?
Get a free, no-obligation site survey and quotation for your commercial property. Our MCS certified team will assess your building and provide a detailed proposal within 5 working days.
Prefer to speak to someone?
01279 295630