Photovoltaic Calculator
Yield • Self-consumption • Feed-in • Benefit • Payback – a quick, realistic orientation.
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What assumptions does the calculator use?
PV Solar Calculator: Yield, Self-Consumption, ROI & CO₂ in One Tool
This calculator estimates the full financial and ecological picture of a rooftop photovoltaic installation — from annual energy yield to payback period. Enter your roof area, orientation, location, household consumption, and system costs to get six key results instantly.
Annual Energy Yield (kWh)
kWp installed × location-specific solar irradiation factor (kWh/kWp/year). Germany average: 950–1,100 kWh/kWp/year. South Germany (Bavaria): up to 1,150 kWh/kWp.
Self-Consumption & Autarky
Share of generated electricity consumed directly by the household (self-consumption rate) and share of total demand covered by PV (autarky rate). Battery storage significantly improves both.
Feed-in Revenue
Surplus electricity fed into the grid × current feed-in tariff (Einspeisevergütung). 2025/2026 rate: ~8.03 ct/kWh for systems ≤10 kWp (EEG 2023).
Annual Financial Benefit
Electricity cost savings (self-consumed kWh × grid price) + feed-in revenue. Total benefit typically €400–1,200/year for a standard 8–10 kWp residential system in Germany.
Payback Period (Years)
System cost ÷ annual financial benefit. For a well-sized German residential system in 2025/2026: typically 9–13 years. With battery: 13–18 years.
CO₂ Savings (kg/year)
Self-consumed + fed-in kWh × German grid emission factor (~380 g CO₂/kWh in 2025). A 8 kWp system saves approximately 2,500–3,500 kg CO₂ per year.
Solar Yield by German Region: Reference Values for the Calculator
The location factor (Standortfaktor) is the most important input for yield accuracy. Here are annual solar irradiation values for key German regions — use the closest city as your reference:
| Region / City | Annual irradiation (kWh/m²) | Yield factor (kWh/kWp) | Relative to DE avg. |
|---|---|---|---|
| Munich / Bavaria | 1,200–1,280 | 1,050–1,150 | +10–15% |
| Stuttgart / Baden-Württemberg | 1,150–1,220 | 1,000–1,080 | +5–10% |
| Frankfurt / Hesse | 1,060–1,120 | 960–1,020 | Average |
| Berlin / Brandenburg | 1,050–1,120 | 950–1,010 | Average |
| Cologne / NRW | 1,000–1,060 | 920–970 | −3–5% |
| Hamburg / North Germany | 960–1,030 | 880–950 | −8–10% |
| Austria (Vienna area) | 1,200–1,300 | 1,050–1,180 | +10–15% |
| Switzerland (Zurich area) | 1,200–1,350 | 1,080–1,200 | +10–20% |
Roof orientation impact: South-facing (180°) = 100% yield. Southeast/Southwest (135°/225°) = ~95%. East/West (90°/270°) = ~80%. North-facing roof: not recommended, ~55–65% yield. The calculator applies an orientation factor automatically when you enter the roof azimuth.
How to Size Your PV System: Rules of Thumb
- Annual consumption → required kWpRough sizing: annual household consumption (kWh) ÷ 900 = recommended kWp. Example: 4,500 kWh/year ÷ 900 = 5 kWp system. This covers approximately 50–70% of demand without battery storage.
- Available roof area → maximum kWpStandard residential panels: ~1.8–2.1 m² per panel, ~400–450 Wp per panel. Rule: 6–7 m² of usable south-facing roof per 1 kWp installed. A 40 m² usable roof supports approximately 6–7 kWp.
- Grid connection limit checkIn Germany, systems ≤25 kWp can generally be connected without a grid study. Systems >25 kWp require a grid impact assessment from the local network operator (Netzbetreiber). Most residential systems (5–15 kWp) are well below this threshold.
- Battery sizing (optional)Battery capacity (kWh) ≈ daily household consumption × 1.0–1.5. For a 4,500 kWh/year household (~12 kWh/day): a 10–15 kWh battery is appropriate. Adding battery increases autarky from ~60% to ~85–90% but extends payback period by 4–6 years.
Frequently Asked Questions
What is the current feed-in tariff (Einspeisevergütung) in Germany?
As of 2025/2026 under EEG 2023: Systems ≤10 kWp receive 8.03 ct/kWh for surplus fed into the grid. Systems 10–40 kWp receive 6.95 ct/kWh for the portion above 10 kWp. These rates are fixed for 20 years from commissioning date. Balkonkraftwerke (plug-in solar, ≤2 kWp) do not require a feed-in tariff contract — they simply reduce your consumption from the grid. Note: the feed-in tariff has been declining steadily; systems commissioned earlier locked in higher rates (up to 43 ct/kWh for 2012 installations).
Is a PV system still financially worthwhile in Germany in 2026?
Yes, primarily through self-consumption savings rather than feed-in revenue. With household electricity prices at ~32–36 ct/kWh (2026) and feed-in rates at ~8 ct/kWh, every kWh you consume directly from your PV system saves roughly 4× more than feeding it into the grid. The financial case for PV is therefore strongest when self-consumption is maximized — ideally combined with an EV (charging from own PV), heat pump (hot water via PV surplus), or home battery. A well-sized system without battery typically achieves payback in 9–12 years against a 20–25 year system lifetime.
Does the calculator account for system degradation over time?
Yes. Modern crystalline silicon panels degrade approximately 0.3–0.5% per year in output. The calculator applies a default 0.4%/year degradation factor over the analysis period (typically 20–25 years). This means a 10 kWp system producing 10,000 kWh in year 1 will produce approximately 9,200 kWh in year 20. You can adjust the degradation rate in the Advanced settings — use manufacturer data for high-quality panels (some premium panels guarantee <0.25%/year degradation).
Do I need planning permission for a rooftop PV system in Germany?
In most German states (Bundesländer), rooftop PV systems on private dwellings are exempt from planning permission (Baugenehmigung) as of 2023–2024, following reforms across most states. However, exceptions exist for: listed buildings (Denkmalschutz), conservation areas (Bebauungsplan restrictions), and systems above a certain size. Always check with your local Bauamt or Gemeinde. You do need to register the system with the Bundesnetzagentur (Marktstammdatenregister) within one month of commissioning — this is mandatory and free of charge.
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