Modeled years to recover the initial cash outlay
✶ YOUR SOLAR FUTURE, CALCULATED THE EVIDENCE EDITION
Make sunlight
make sense.
One considered place to design solar, understand every kilowatt-hour and discover what your investment could actually return.
EU JRC PVGIS 5.3 Auditable cash flows Private by design
01 / THE DECISION
Your investment, in focus.
Present value of net future cash flows
Expected site-specific generation
Annual demand covered by solar energy
After operating costs and replacements
Discounted project cost per produced kWh
02 / ENERGY SEASONS
A year, illuminated.
Solar output split between your home and the grid.
Used at home Sent to grid
03 / FINANCIAL TRAJECTORY
The return curve.
Lifetime cumulative net project cash flow.
Cumulative net cash Break-even
04 / POWER BALANCE
Where your energy goes.
Annual PV production and household consumption.
--PV self-consumed
Used on-site--
Sold / exported--
Bought from grid--
Annual usage--
05 / YOUR NEXT ADVANTAGE
Better choices, backed by math.
Every opportunity below changes a real input.
PV production is illustrative until EU PVGIS returns data. Financial inputs are not live supplier tariffs.
02 / DESIGN STUDIO
Built for your roof.
Start with your address, size and panel geometry. Climate production updates when your PV configuration changes.
01
Where will it live?
Search a city or use roof coordinates.
02
Define your solar array.
Generation is calculated using this exact setup.
Quick PV size5.5 kWp
03
Roof-fit sketch.
Area-based planning, not a structural or electrical design.
YOUR ROOFTOP / CONCEPT SKETCHPROPORTION STUDY
NOT TO SCALE / NO SHADE STUDY
Estimated roof capacity--
Modules by area--
Usable roof area--
Do not buy panels based on this area estimate alone. Confirm structural loads, setbacks, walkways and shading.
ACTIVE SOLAR SOURCE
Illustrative / awaiting PVGISPVGIS estimates historical climate output for the chosen coordinates, geometry and mounting. This is not shade modeling.
03 / HOUSEHOLD INTELLIGENCE
Every hour matters.
Understand direct self-use and grid imports. Connect real 8,760-hour consumption data for higher-confidence energy matching.
01
Your electricity demand.
Use the variable tariff you can actually avoid.
Direct self-use assumption45%
Until you import matching hourly data, this is an assumption, not a meter-derived measurement.
02
Upgrade to hourly fidelity.
Private local meter data + actual PVGIS hourly history.
UTC-aligned 8,760-hour year, consumption in kWh. Nothing uploaded to our server.
No meter file loaded.
PVGIS hourly series not loaded.
ENERGY PROFILE
Consumption meets generation.
Representative 24-hour shape; not a metered trace until aligned hourly data is imported.
Solar production Home demand
Annual solar self-use--
Grid electricity imported--
Energy independence--
Analysis typeAssumed
04 / STORAGE ECONOMICS
Power for after sunset.
Compare PV alone with PV plus battery. See the real incremental financial impact, not a blanket promise that storage always wins.
01
Configure your battery.
The model includes conversion losses and annual capacity fade.
Battery capacity0 kWh
Without measured hourly usage, storage is an approximate monthly scenario. Backup behavior, replacement schedules and tariffs may differ.
ENERGY STORED, VALUE EXPLAINED
0kWh
Storage is a choice, not an assumption.
See whether extra self-consumption pays for the installed battery in your specific scenario.
Independence improvement--
Incremental NPV--
THE ACTUAL TRADEOFF
PV-only vs PV plus storage.
Incremental value after added battery cost and energy losses.
| Configuration | Annual self-use | Energy independence | Net present value | Payback |
|---|
05 / THE OPPORTUNITY LAB
Explore the upside.
Compare grounded changes, size alternative PV arrays and preserve useful scenarios without guesswork.
WHAT IF YOU CHANGED ONE THING?
Three levers worth testing.
Each delta is recomputed from your current inputs, not a generic savings claim.
RISK & RESILIENCE
How robust is the return?
These are deterministic stress scenarios, not probability forecasts.
RIGHT SIZE IT
Which array size fits your economics?
Alternative sizes scale baseline PVGIS yield linearly and installed cost per kWp; quotes and roof constraints must be verified.
Select Calculate alternatives to compare PV sizes.
SCENARIO VAULT
Keep your best ideas.
Saved locally in your browser. Export JSON for a backup.
06 / THE MONEY MODEL
Every number. Accounted for.
Investment, annual cash flows, avoided electricity, export payments, debt, discounting, maintenance and replacements.
01
Actual price assumptions.
Replace defaults with the variable part of your real bill.
Long-term financial assumptions
PROJECT ECONOMICS / MODELLED RETURNS
Net present value--
Positive NPV means the modeled investment exceeds the discount-rate hurdle. It is not a guarantee.
Internal rate of return--
Initial cash cost--
Lifetime net benefit--
Discounted payback--
OPTIONAL FINANCING
Equity NPV--
Annual loan payment--
FULL AUDIT TRAIL
Lifetime cash-flow ledger.
Annual production, savings, export income and costs.
| Year | Production | Self-use | Export | Bill avoidance | Export income | Opex / replacement | Net cash | Cumulative |
|---|
07 / DATA INTEGRITY
Evidence over exaggeration.
Know what is measured, derived, user-supplied or only illustrative. No secret supplier prices or invented panel measurements.
01
Solar climate source
European Commission PVGIS 5.3, monthly PV generation estimated over historical weather years. Real PVGIS results are source-labeled, not future guarantees.
Official API documentation ↗02
Location lookup
Open-Meteo geocoding provides city coordinates, not roof address validation. Manual coordinates remain available.
Open-Meteo documentation ↗03
What is assumed?
Hardware costs, tariff compensation, future inflation, performance aging, subsidies, insurance, rate discounting and self-use are inputs unless real meter data is imported.
DATA LINEAGE
The information behind your report.
Run an API health check to verify the deployed Cloudflare Worker.
BEFORE YOU INVEST
Practical due diligence.
Check these outside the calculator before accepting a quotation.
Methodology boundary
PVGIS describes historical solar resource; it does not inspect the exact roof, predict future electricity prices, verify your bill, guarantee a subsidy or replace engineering or financial advice. When an upstream API is unavailable, results are explicitly marked illustrative. SolarPayback stores scenarios in your browser only; imported meter files remain in memory.