An honest answer to
“is solar worth it for me?”
The Solar Credit Calculator gives UK homeowners a personalised, data-driven estimate of what rooftop solar could save them: in under five minutes, with no sales pressure.
🎯 Why we built it
Most solar “calculators” online are lead-capture forms dressed up as tools: enter your details, get a vague number, then field a week of cold calls. The honest information (how much you'd actually generate on your roof, what you'd save against your bills, and how long it takes to pay back) is usually the part they hide.
We wanted the opposite: a tool that does the real maths transparently, shows its working, and lets you reach your own conclusion before you ever speak to an installer. The goal is a number you can trust enough to act on.
⚙️ How the estimate is built
Rather than a one-size-fits-all rule of thumb, the calculator models your specific situation from a handful of questions about your home and energy use:
☀️ Real solar yield
Generation is modelled from satellite-derived irradiance for your location, adjusted for roof orientation, pitch and any shading.
🏡 Your actual consumption
Usage is estimated from property type, bedrooms, EPC rating, occupancy, heating type and whether you run an EV or heat pump.
💷 Live-ish tariffs
Import and export (SEG) rates are based on current published supplier and Ofgem figures, with the ability to compare suppliers.
📈 25-year outlook
We project net benefit over the system's life — accounting for panel degradation, energy-price inflation and finance costs — not just year one.
🧭 What we stand for
🔍 Transparent
Every figure has a “what shaped your number” breakdown and a cited source. No black boxes.
🤝 Independent
The estimate isn't tuned to sell you a bigger system. We'd rather be useful than optimistic.
🔒 Privacy-first
We only ask for what the maths needs, and we explain how it's handled in our Privacy Policy.
📚 Evidence-based
Assumptions come from public, authoritative datasets — and we update them as those change.
🗂️ Where our data comes from
- PVGIS (European Commission JRC)Satellite-derived solar irradiance used to model location-specific generation.
- GOV.UK EPC Register (DLUHC)Energy Performance Certificate data to refine property energy estimates.
- GOV.UK Solar PV & MCS Cost DataMedian installation and battery costs from the MCS certification database (2024/25).
- OfgemPrice-cap unit rates and Smart Export Guarantee (SEG) benchmarks.
- DESNZ NEED & Ofgem TDCVTypical domestic consumption values, recalibrated to the latest 2026 figures.
👋 Who's behind it
The Solar Credit Calculator is built and maintained by Kieran Zhané. It started as a personal project to answer one frustrating question honestly, and is being developed in the open into a proper tool for UK households considering solar.
It's currently in BETA — actively improving, with new accuracy and usability work shipping regularly.
🚀 See your own estimate
Ready to find out what solar could do for your home?