Solar Calculator (PV System Calculation)
Calculate your photovoltaic system with current PVGis data incl. shading analysis and sun simulation.
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.
To detailed solar guide with formulas and calculation basics →