How do I use the commercial solar calculator?

Enter your available roof area in square metres, your annual electricity usage in kWh, your current unit price in pence per kWh, and select your UK region. The calculator instantly estimates your recommended system size, installation cost, annual savings, payback period, 30-year NPV, and carbon reduction.

How accurate is the solar ROI calculator?

The calculator uses current UK industry benchmarks for installation costs (£/kWp), regional irradiance data, and typical system performance ratios. Results are indicative estimates based on your inputs — a formal site survey by a qualified installer will provide a precise quote.

What is the difference between self-funded and PPA solar?

Self-funded solar means you purchase and own the system outright, paying upfront capital but retaining all savings and achieving full payback typically within 4–6 years. A Power Purchase Agreement (PPA) means a third party owns and installs the panels at no upfront cost to you — you buy the electricity generated at a fixed rate below market price, with savings from day one but no asset ownership.

Does the calculator include battery storage?

The calculator focuses on solar PV generation and ROI. Battery storage can be discussed as an add-on during a consultation with Kinetic Energy Consulting, where the impact on self-consumption rates and payback can be modelled for your specific site.

Free Commercial Solar ROI Calculator

Your Solar Analysis

How would you like to fund this system?

PPA Configuration — rates sourced from your region & system size

PPA Contract Length

— p/kWh

PPA rate for your region & system size (auto-calculated)

System Overview

Roof Area

—

m²

Panels Fitted

—

× 450W

System Size

—

kWp

Year 1 Generation

—

kWh

30yr Generation

—

kWh

Financial Summary

Installation Cost

—

GBP total

30yr Savings

—

GBP

Return on Investment

—

% over 30 years

Payback Period

—

years

CO₂ Offset

—

tonnes (30yr)

Break-Even Analysis

Cumulative Savings

Initial Investment

Year-by-Year Savings — First 10 Years

Assumptions & Limitations

Maintenance costs NOT included. Typically £15–£20/kWp/year.

Roof/mount coverage: 80–90% of total area assumed usable depending on mount type, accounting for edge setbacks, obstructions, and inter-row spacing.

Self-consumption: 70% of generation is assumed consumed on-site, displacing grid electricity at the import rate.

Export upside: the remaining 20% exported at a nominal 5p/kWh (SEG rate) is shown separately above as additional upside only — excluded from savings as export rates are not guaranteed and vary by DNO and tariff.

Panel degradation: 0.5% per year (manufacturer linear performance warranty standard).

Electricity price inflation: 3% per year.

Panel spec: 450W, 2.27m × 1.13m (2.57m²). System efficiency (performance ratio): 80%. Installation cost is all-inclusive (panels, inverters, mounting, electrical, commissioning).

Carbon factor: 0.196 kg CO₂/kWh (UK grid 2026).

Does not include costs for scaffolding, surveys such as structural and also any grid associated costs or upgrades.

Important Notice

This is a rough, hypothetical calculation based on very basic input information. For a more detailed design and accurate costings and savings please contact:

Martyn Sheridan

martynsheridan621@gmail.com · +44 (0) 787 2015769