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Solar Panel ROI: Calculate Your Savings Worldwide

Estimate system size, annual production, savings and payback for any rooftop on the planet. Choose your region — the engine does the rest.

Quick Start

Step 1. Measure
usable roof area
Step 2. Select
your region
Step 3. Enter
electricity price
Step 4. Get
ROI & payback

Tip: Defaults are industry-standard. Adjust only what you know for your project.

Project Inputs

Grouped by climate and solar potential (kWh/kWp/year).
Net area, excluding chimneys and skylights.
Typical modern modules: 380–450 W.
Northern hemisphere. For southern hemisphere, "North" ≈ "South".
Trees, buildings and seasonal shading.
Set to 0 if no export compensation.
Share of solar used on-site directly.
Turnkey: modules + inverter + labour.
Display only — e.g. EUR, USD, NOK.
System design & ROI
Core KPIs for your solar project, based on the inputs to the left.
System size kWp & panels
–
–
Annual production kWh / year
–
–
Annual savings self-use + export
–
–
Payback time simple payback
–
–
Load coverage:–
Self-consumption:–
Yield:–
25-year net:–

Assumptions: Region-specific solar yield (kWh/kWp/year), standard system losses, no degradation, simple payback (no discount rate). For feasibility studies, adjust inputs to your local market and regulations.

New to solar? Click here for a complete guide

How to use the Solar Panel Calculator:

Step 1: Measure your roof

Measure the net usable area (length × width) of the roof section you want to install panels on. Subtract chimneys, skylights and vents.

Step 2: Select your region

Your region determines the solar irradiance (how much sun energy is available per year). Northern Europe averages ~900 kWh/kWp/year; Southern Europe ~1350; desert regions up to 1850.

Step 3: Enter your electricity price

Use your total electricity price including grid fees and taxes. This directly determines your savings and payback period.

Step 4: Set self-consumption

This is the share of solar energy you actually use in your home. A typical household without battery storage is 50–65%. With battery storage, you can reach 80–90%.

Pro tip: South-facing roofs at 30–40° tilt produce the most energy in the Northern hemisphere. East/west orientations produce ~10% less but spread production more evenly through the day.
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