When an electric car charges, it does not necessarily do so exclusively from surplus production from solar panels.
There are several technical limitations that can prevent this, including the car's own requirements and the solar panels' production.
Here are the main reasons:
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The car’s minimum charging power
Electric cars have a minimum power requirement to initiate charging.
Many EVs typically require at least 1.4–1.5 kW for single-phase charging (230V, 6A).
If the solar panel surplus is below this level, the car will not start charging at all. -
Fluctuating solar panel production
Solar panels generate electricity depending on sunlight, which varies throughout the day.
If production drops below the car’s minimum requirement (e.g., due to a cloud), charging may stop.
Many cars do not automatically resume charging when production once again exceeds the minimum threshold. -
Limitations from the car manufacturer
Some EVs have strict charging requirements and built-in controls that prevent low-power charging.
Certain cars require a stable power supply and cannot handle rapidly fluctuating power levels from solar panels. -
Charging cable limitations
Many standard charging cables have a minimum current requirement of 6A (1.4 kW).
If the solar surplus is lower than this, the charger cannot activate the charging process. -
Car’s charging settings
Some EVs have a fixed minimum current that cannot be adjusted manually.
Certain cars allow scheduled charging but do not necessarily support charging based on solar production.
The "Scheduled Charging" function may also prevent the car from starting a charging cycle if set to charge only at specific times.
In practice, these limitations mean that an EV rarely charges exclusively from solar surplus when production is low.