Photovoltaic Calculator | Yield & Profitability
Quick Start
What Does This Calculator Compute?
The solar calculator determines electricity yield, self-consumption, profitability and CO₂ savings of your planned photovoltaic system. Based on precise PVGis climate data (European Commission), you receive realistic forecasts for your location.
Why do you need this calculation?
- System sizing: How many kWp do I need?
- Self-consumption optimization: How independent will I become from the grid?
- Profitability: When will the investment pay off?
- Storage planning: Is a battery storage worthwhile?
- Shading analysis: How much do obstacles affect the yield?
Important: Results are based on long-term averages. Actual yields may vary by ±5-10%.
The 5 Input Tabs
Tab 1: Location
Enter the address. The calculator automatically determines:
- GPS coordinates and elevation
- PVGis climate data: Hourly solar irradiation for 8,760 hours/year
Supported countries: Germany, Austria, Switzerland, France, Italy
Tab 2: Surfaces (PV Modules)
Define your roof surfaces:
- Power [kWp]: Total module power
- Azimuth [°]: Orientation (0° = South, 90° = West, -90° = East)
- Tilt [°]: Roof pitch (optimal: 30-35° for Germany)
- System losses [%]: Lump sum for cables, inverter (default: 14%)
Shading Analysis : For each surface, you can draw obstacles (trees, buildings, chimneys) and start the sun simulation to calculate hourly shading losses.
Tab 3: Consumption
Enter your electricity consumption:
- Annual consumption [kWh]: From last electricity bill
- Household profile: Family, professionals, home office, retirees
- Individual consumers: Optional for more precise calculation (heat pump, EV, etc.)
Tab 4: Storage (optional)
Configure a battery storage:
- Capacity [kWh]: Quick-select 5/10/15/20 kWh or manual entry
- Efficiency [%]: Typically 90-95%
Recommendation: Capacity ≈ 70% of daily consumption (at 4,000 kWh/year → approx. 7-8 kWh)
Tab 5: Finances
Economic parameters:
- System costs [€]: Guideline €1,200/kWp
- Electricity price [ct/kWh]: Your current purchase price
- Feed-in tariff [ct/kWh]: Currently 8.1 ct/kWh (up to 10 kWp)
- Analysis period [years]: Typically 20-25 years
Understanding Results
After calculation, you receive results in 4 tabs:
Tab 1: Overview
Four key metric cards:
- Annual yield [kWh/year]: Produced electricity
- Self-sufficiency rate [%]: How independent you become
- Annual savings [€/year]: Saved electricity costs
- CO₂ savings [kg/year]: Your contribution to climate protection
Tab 2: Finances
- Before/after comparison: Electricity costs with and without PV
- Payback period: When has the system paid for itself?
- Cumulative savings: Development over the years
Tab 3: Yield
- Self-consumption vs. feed-in: How much do you use yourself?
- Monthly distribution: Yield and consumption per month
- Pie charts: Visualization of energy flows
Tab 4: Surfaces
- Detailed results per surface: Yield, shading losses
- Hourly generation: Typical daily profile
Shading Analysis: How It Works
The shading analysis is a highlight of the solar calculator:
- Open shading editor: Click on "Analyze shading"
- Draw obstacles: Place buildings, trees, chimneys
- Enter heights: How tall is the obstacle?
- Start sun simulation: Observe shadow casting throughout the day
- Calculate losses: Automatic calculation of annual yield losses
| Obstacle | Typical loss |
|---|---|
| Chimney | 2-5% |
| Single tree | 5-15% |
| Neighboring building | 10-30% |
Tip: Shading in summer (March-October) is more critical than in winter, as most yield is generated during this time.
Tips for Best Results
Optimize orientation: South = 100%, East-West = approx. 85% yield
Check tilt: 30-35° are optimal for Germany
Maximize self-consumption: Use large consumers (washing machine, EV) during daytime
Size storage realistically: Too large is uneconomical
Check shading: Even small obstacles can cause significant losses
Frequently Asked Questions
How accurate are the forecasts?
Calculations are based on PVGis data with a typical deviation of ±5-10% compared to actual yields.
Can I combine multiple roof surfaces?
Yes! You can create any number of surfaces with different orientations (e.g., East-West system).
Is a battery storage worthwhile?
The finance tab shows this. Storage increases self-sufficiency from ~30% to ~60-70%, but extends the payback period.
Do I need a permit?
PV systems on roofs are usually permit-free, but registration with grid operator and market master data register is mandatory.
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