Estimate the kWh you need
A session depends on the car battery, current charge, target charge, and charger power. Power Window estimates the energy first:
needed kWh = battery kWh * (target - current) / 100
A Power Window guide to planning home EV charging.
How to choose the best time to charge an EV at home
Timing changes the energy cost only if your contract has rates that vary by time. With one fixed rate all day, moving the same charge does not save energy cost. With period rates, use your contract prices; with PVPC, check the published hourly prices. Compare a window covering the whole session, not just its first hour.
The Spanish regulator's bill guide helps identify your tariff. Power Window prepares this guide; see the calculation and its limits.
Find a complete window
If you need three, five, or eight hours, the full-session average matters more than a single cheap hour. The app ranks continuous windows.
Separate energy price from the full bill
PVPC helps choose timing. A final bill can include contracted power, taxes, charges, retailer margin, and other items that do not change when the session moves.
Check before plugging in
Solar-heavy days can favor midday; other days, cheap hours appear overnight. The hourly curve should decide, not a fixed rule.
How to decide when to charge an electric car
For long sessions, the key number is not only the daily minimum hour. Your cost depends on the average price across every hour while the car is charging.
If you only need a small top-up
When you only want to recover 10% or 20% of the battery, two or three hours may be enough. A short window near the daily minimum often works well. The planner estimates duration from battery size, current charge, target charge, and charger power.
If you need many kWh
For a large recharge, one cheap hour does not define the full cost. It is better to find a continuous block with a low average price. That is why Power Window ranks complete windows rather than pointing at one isolated hour.
Wallbox, socket, and three-phase charging
The same energy takes different time depending on the charger. A 2.3 kW domestic socket may need many hours, a 7.4 kW wallbox concentrates the session, and an 11 kW three-phase installation changes the best window again. Enter the real power before deciding.
EV charging with your contract rate
When is it cheapest to charge an electric car in Spain?
It depends on your contract and charging duration. With one fixed rate all day, moving the same charge does not lower its energy cost. With period rates, compare your contract prices; with PVPC, check today's available hours. Compare the complete session in either case.
What data do I need?
Car model or battery size, current charge, target charge, and charger power. Those inputs estimate how long the charge needs to run.
Does it work for a 7.4 kW wallbox?
Yes. You can also model a 2.3 kW socket, 3.7 kW slow charger, or 11 kW three-phase charging. The recommendation changes with duration.