Commercial Solar Sizing & ROI Calculator
Model indicative system capacity (kWp), annual cost avoidance (£), 100% First-Year AIA corporation tax shelter, and net amortised payback for your UK commercial facility.
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Our commercial installation partners are rigorously vetted and accredited to the UK's highest technical, electrical, and site-safety standards:
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Facility Parameters
Indicative Financial Returns
Calculation Methodology & Engineering Assumptions
1. Solar Yield Estimation: Systems are modelled based on UK industry geographic averages yielding approximately 900 kWh per kWp installed annually, utilizing Tier-1 monocrystalline panels with half-cut cell technology.
2. Tariff Displacement: Behind-the-meter self-consumed electricity displaces retail imported electricity at 25p/kWh (representing the 2026 UK non-domestic blended wholesale and network distribution average). Unconsumed power is credited at an indicative corporate PPA export rate of 7p/kWh.
3. Corporation Tax Shelter (AIA): Under the UK Capital Allowances Act 2001 (Section 51A), qualifying solar equipment expenditures up to £1,000,000 benefit from 100% first-year Annual Investment Allowance (AIA), providing an effective 25% cash tax deduction against taxable profits.
4. Business Rates Exemption: In accordance with statutory regulations, plant and machinery deployed for on-site clean electricity generation and storage is 100% exempt from business rates assessments until at least 31 March 2035.
Calculator FAQs
Frequently Asked Questions
How does the commercial solar calculator estimate system sizing?
System capacity is estimated by balancing your monthly electricity expenditure against your usable roof area (assuming approximately 60 sq ft per kWp installed). Sizing is calibrated to your industry's operating hours and self-consumption profile to maximize on-site grid displacement.
What tariff assumptions are used for electricity savings?
The calculator models self-consumed solar electricity displacing grid imports at 25p per kWh (reflecting average 2026 UK commercial tariffs including CCL, DUoS, and TNUoS charges), with unconsumed surplus exported at 7p per kWh.
How is the 100% Annual Investment Allowance (AIA) tax relief calculated?
Under Section 51A of the Capital Allowances Act 2001, commercial solar qualifies for a 100% first-year deduction against pre-tax profits up to £1,000,000. At the current main UK corporation tax rate of 25%, this yields an immediate cash tax saving equal to 25% of gross capital expenditure in year one.
Is this calculator estimate an official quote?
No. The calculator provides an indicative desk assessment based on UK industry benchmarks. Actual commercial quotations require a physical or 3D satellite survey of roof structural loading (BS EN 1991) and a formal G99 grid connection assessment by your regional DNO.