How many solar panels does each one really need?
The Model 3 Long Range and the i4 eDrive40 are two of the most cross-shopped EVs in Europe — but they're not equally cheap to run on solar. The Model 3's 75 kWh battery and 13.8 kWh/100km consumption make it noticeably more efficient than the i4's 84 kWh pack at 16.3 kWh/100km, which shows up directly in how many panels each needs and how fast the system pays for itself.
Model 3 wins on every metric — 1 fewer panel and a payback 0.1 years sooner.
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Common Questions
It depends on your annual mileage and location, but the Model 3's lower consumption (13.8 kWh/100km vs the i4's 16.3 kWh/100km) means it typically needs fewer 400W panels to cover the same annual driving. VoltSun calculates the exact count for your address and driving habits below.
Payback period depends on install cost, electricity price, and how much solar energy the car actually consumes. Because the Model 3 needs less energy per km, a same-size solar system covers a larger share of its charging — which usually means a shorter payback period, though your local electricity price matters just as much.
Battery size alone doesn't determine panel count — annual energy consumption does. The i4's 84 kWh battery is larger than the Model 3's 75 kWh, but what matters for solar sizing is kWh consumed per 100km, where the i4 uses about 18% more energy than the Model 3.
On paper, the Model 3 Long Range is the more efficient of the two at 13.8 kWh/100km vs the i4's 16.3 kWh/100km — a real-world difference of roughly 2.5 kWh per 100km, which adds up over 15,000+ km/year into a meaningfully different solar system size.