How many solar panels are necessary to charge an electric car at home?


The great advantage of the electric car is the fuel savings that it entails, in addition to the reduction of pollution, compared to traditional combustion engines. But yes, also we charge with solar energy, we can move free daily. In order to do so, several aspects must be taken into account, such as daylight hours, the number of plates, the type of installation or the kilometers that we will cover every dayamong others.

The year 2022 has consolidated the photovoltaic energy sector in Spain and the number of families that have installed solar panels in their homes to mitigate the impact of the rise in electricity (more than 13,000 customers). In addition, she left certain green shoots in electric car registrations. Dealers sold 36,444 vehicles, 31.28% more than in 2021, and another 48,193 plug-in hybrids. Two points in common that can well be used to achieve a more sustainable and economical mobility.

What photovoltaic installations allow electric cars to be charged?

Charging a car through self-consumption at home is possible, but keep in mind that at night and on cloudy days It is advisable to have enough contracted power in case the plates do not generate the necessary energy. In winter the plates yield, since they work with light and do not depend on the amount of heat or temperature. The possibilities are these:

  • Self-consumption photovoltaic installation connected to the electricity grid. This is the most recommended option, since energy can be consumed both from the panels and from the electrical network if necessary. In addition, there are rates with surpluses and compensation. In other words, the energy generated by the panels that has not been consumed is poured into the network and the retailer applies a discount on the electricity bill, depending on the kilowatts. The price of surplus energy changes every hour, but is approximately 0.05 – 0.06 €/kWh.
  • Isolated photovoltaic installation: It is an option that is not recommended. As it is independent from the electrical network, the energy is stored in storage batteries. However, the task of recharging the car on cloudy days is complicated, since it is possible that the accumulated energy in the batteries runs out and the house is left without light while there are no rays of sun. It is an option for country houses or similar and where there is a second diesel or gasoline vehicle to be able to move.
Photovoltaic generation plant in Villarrubia de los Ojos (Ciudad Real).

How many solar panels do I need to recharge an electric car?

Once we know that the best option is an installation connected to the network that allows us to charge our car at all times, day or night, the number of plates to install at home must always be based on the specialist study. We must specify that we want to have enough power to cover the needs of a living place as to be able to recharge a electric vehicle.

If we make an estimate, a normal solar panel can provide 250-300W of power per hour, although I could even vary from 150 to 500W. In addition to the power of the panel itself, the geographical area, the hours of sun also influence… To calculate the kW that it will generate in a day, you must multiply the hours of sun by the amount of power from our solar panel. For example, if the panel generates 250Wh and receives 8 hours of sun, after one day it will be 2,000W (2kW).

Taking into account that the battery of an electric utility car part of the 40kW, the calculation would be simple. We would need 20 plates to fully charge it in one day. The estimated autonomy, depending on the car, would be about 250 or 300 kilometers. But it is not normal to travel that distance on a daily basis. If, for example, they are only going to be 50 kilometers a day, they would serve us with five license plates. To know if it is profitable, you have to Take into account the annual kilometers, the price of the plates and the installation.

Underfloor heating installation

In addition to this, according to REE (Red Eléctrica de España), average daily consumption in a Spanish home is 9 kW hour. That is to say, another five plates would be needed to generate another 2kW per day to make the facility self-sufficient. In this sense, the OCU indicates that the ideal “would be to be able to produce exactly the same as the installation consumes”, something very complicated, so it is always better “for photovoltaic systems for self-consumption to be ‘undersized’ rather than ‘oversized’ “, that is, that production is never greater than consumption.

Can it be charged overnight?

It is a less recommended option and it will not always be possible if there have not been enough hours of light during the day. But it can be done. It is achieved through storage batteries. A highly recommended element for photovoltaic installations where most of the consumption is carried out in the hours when there is no sun. Its price is very varied, up to a maximum of 6,000 euros, but you can request the grants of up to 490 euros through the Next Generation fund incentives for renewable energy installations.

these batteries They accumulate photovoltaic energy and transform it into alternating current. They store it during the production peaks in the hours of sun for its use, with an estimated loss of 10% of the energy. It must be taken into account that in the case of being several days without generating energy solar, you can completely empty the batteries and run out of supply. For this reason, it is always recommended that the installation be connected to the electrical network.

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