Path-Q Solar
How should a second electric vehicle change a solar system planned for one vehicle?
Answer
Recalculate the system using the combined annual charging energy and the times when both vehicles charge. A second vehicle may require more panels, a larger inverter, managed charging, or a battery, but the added solar capacity should be based on actual miles, vehicle efficiency, charging losses, and available charging time rather than vehicle count alone.
Key points
- Estimate annual miles and electricity use for each vehicle, including charging losses.
- Check whether the service, charger circuits, and inverter can support simultaneous charging.
- Daytime charging can use solar directly; overnight charging increases the value of additional capacity, load management, or storage.
- If the roof cannot support the full offset, prioritize the loads and charging periods with the greatest value.
What it depends on
- Annual miles and efficiency of both vehicles
- Charging power, schedule, and whether charging overlaps
- Existing and proposed solar production
- Electrical service capacity and available roof area
- Whether a battery or managed charging is planned
Risks and trade-offs
- Sizing only for one vehicle can understate future consumption.
- Sizing for maximum simultaneous charging can increase equipment cost and may require electrical upgrades.
- Vehicle usage may vary substantially, so a large system can be underused if driving patterns change.
Information you may need
- Estimated annual miles for each vehicle
- Vehicle efficiency or expected kWh per mile
- Charging times and charger ratings
- Existing bills or interval usage data
- Roof, service, and inverter constraints
Your next step
What to do next
Ask for a revised design that models both vehicles separately, shows their annual charging load by time period, and compares unmanaged charging with managed charging or storage.
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