Precision Financial Modeling for Your Home
Location & Roof Geometry
We calculate peak sun hours based on your UK region, roof orientation (south-, east-, or west-facing), and pitch angle using standard SAP/MCS yield formulas.
Usage Pattern Matching
The calculator maps your daily occupancy habits against typical load profiles to determine how much solar power you will consume directly versus export.
Smart Tariff Optimization
It factors in off-peak night-charging tariffs (e.g., 7p/kWh) and Smart Export Guarantee (SEG) payouts (up to 15p/kWh) to deliver accurate, 25-year financial projections.
25 YEAR LIFETIME CASH FLOW
25 Year Financial Return vs Grid Inflation
Compare your total expenditure over 25 years with a solar and battery system versus paying rising grid energy prices.
Cumulative cost / return over time
£ Cumulative 25 Year Model
Financial Milestones
Financial Milestone
Year 1
Year 5 (Payback Point)
Year 10
Year 25 (Lifetime Yield)
Grid power only (cum. cost)
~£2,100
~£11,500
~£26,000
~£85,000+
Solar + battery system (net cost)
~£7,500 (upfront)
£0 Break-even
+£7,200 net profit
+£31,500 net profit
Self-sufficiency
75%
78%
80%
80%
Standard Fixed Tariff
Generating solar energy during the day reduces your reliance on flat-rate grid electricity (typically around 28p/kWh), helping lower your monthly energy costs. Any unused solar power can be exported back to the grid at basic SEG rates of around 15p/kWh, adding extra value to your system. By increasing direct self-consumption, you protect your business against rising electricity prices, enhance long-term savings, and maximise your overall return on investment.
Smart Time-of-Use Tariff
Take advantage of time-based electricity rates by generating solar energy during peak daylight hours and using or exporting it when electricity prices are higher. A smart time-of-use tariff helps you maximise the value of your solar power, reduce reliance on the grid during expensive periods, and significantly lower your energy bills. With intelligent energy management, you can align your solar generation and consumption with the highest-value time slots, improving both savings and return on investment.
The Overnight Off-Peak Tariff
Make the most of lower overnight electricity rates by storing energy in your battery to power your operations when the sun isn’t shining. The Overnight Off-Peak tariff allows you to charge your system with low-cost grid electricity during off-peak hours and discharge it during high-tariff periods, significantly reducing your reliance on expensive peak rates. This approach maximises self-consumption, lowers your energy bills, and accelerates your return on investment.
FREE ASSESSMENT
Turn Your Roof into a Private Power Plant Today
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COMMON QUESTIONS
Frequently Asked Questions About Our Calculator
How accurate are the financial estimates generated by this calculator?
Our calculator uses real time regional UK solar irradiance data MCS standard performance factors and current 2026 energy price cap data. Final figures are finalized during your physical roof survey.
Does the calculator include the 0% VAT government incentive?
Yes! All system cost estimates automatically apply the UK Government’s 0% VAT rate on residential solar PV and battery storage systems.
What electricity price inflation rate is assumed in the 25 year projections?
Projections use a conservative historical average energy price inflation rate of 5% per annum, reflecting long-term UK grid price trends.
Can i save my calculation results for later?
Yes. Simply click “Email Me My Detailed Calculation Report” to receive a full breakdown PDF containing your customized yield curves and equipment recommendations.
Turn Your Estimates Into a Fixed Price Engineering Proposal
Get a verified 3D roof design, shade analysis, and guaranteed fixed-price quote from our MCS-certified engineers.