How Many kWh Does a Solar Panel Produce Per Day?
A standard 400W panel produces 1.0–2.8 kWh per day depending on location and season. Here's the real math — by city, by month, and what it means for your EV.
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The Short Answer
A standard 400W monocrystalline panel produces between 1.0 and 2.8 kWh per day depending on your location, season, and installation angle. Averaged across a full year, most European installations land between 1.2 and 1.8 kWh per panel per day.
Peak Sun Hours Explained
Solar kWh production is calculated using peak sun hours — the number of hours per day that solar irradiance averages 1,000 W/m² (standard test conditions). It doesn't mean hours of daylight; it's a measure of effective radiation intensity.
A 400W panel in a location with 4 peak sun hours/day produces:
400W × 4h × 0.80 system efficiency = 1.28 kWh/dayThe 0.80 factor covers real-world losses: inverter efficiency (~96%), temperature derating (~95%), wiring (~98%), and soiling (~91%).
Output by European City
| City | Peak sun hours/day | Annual yield per 400W panel |
|---|---|---|
| Madrid, Spain | 5.1 | 593 kWh |
| Rome, Italy | 4.7 | 547 kWh |
| Belgrade, Serbia | 4.2 | 489 kWh |
| Vienna, Austria | 3.8 | 442 kWh |
| Paris, France | 3.5 | 407 kWh |
| Berlin, Germany | 3.3 | 384 kWh |
| London, UK | 2.9 | 337 kWh |
Monthly Variation
Production is not uniform across the year. In central Europe, a single panel might produce:
- June (peak): 3.2–4.0 kWh/day
- September: 1.8–2.2 kWh/day
- December (low): 0.4–0.7 kWh/day
This seasonal swing matters most if you're sizing a system specifically for winter needs — you'd need roughly 4–5× more panels to maintain winter output compared to designing for annual average.
How This Translates to EV Charging
For an EV using 18 kWh per 100 km, 1.5 kWh/day of solar covers about 8 km of driving. Across a year, a single 400W panel covers approximately 2,700 km — enough for a short daily commute on its own.
Enter your address in the VoltSun calculator to get exact daily and monthly kWh production figures for your specific coordinates.
Track your real output: The Emporia Vue 3 → home energy monitor shows real-time solar production vs. consumption, accurate to within 1–2%. Solar and net metering compatible, with an app that breaks down hourly solar yield — useful for validating your VoltSun estimate against actual panel performance.