Electric vehicles have an important role to play in the low-carbon future. Plug-in electric vehicles (EVs) sales have been growing steadily in Europe. According to Renault Z.E., which tracks electric vehicle sales across Europe, all-electric vehicle sales in the region rose 55 percent in the first half of 2015 compared to the first six months of 2014. The United Kingdom saw the biggest increase, with sales up 80 percent, amounting to roughly 5,000 units sold. Norway still leads the region in overall numbers, however, with sales up 47 percent, reaching around 15,000 EVs sold in the first half of the year.
Although EVs still represent a small fraction of the EU-s 230 million total vehicles, the continual increase in sales suggests that EVs will become even more popular over the next few decades. This raises the question of how millions of EVs may be charged at once on a grid that was not originally intended to supply such large amounts of power.
With the high penetration of electric vehicles, charging at home will increase the stress on the last end of local distribution networks. The cost of upgrading the last “mile” of the network, however, would be prohibitive, as this would skyrocket the network tariffs to the consumers. Also network operator have to maintain the fairness factor to the other users of the same network.
With the advances of internet technologies, we might see a comprehensive algorithms to be devised that allow distributing the power quickly and fairly. Whereas another approach might be, that in the future we the networks tariffs change dynamically in the future just as the energy prices do today.
Different charging levels
Electric vehicle charging types can be split into three levels, which are very well explained by CNET. Your standard home outlet in the EU offers 250 volts of alternating current, with a circuit breaker rated at 16 amps. This is the level 1. Most electric cars come with J1772 SAE electric-car-charging plug, where one end connects to the outlet and the other one to the car. The charging time with the standard outlet depends on what model car you have and from which battery level you are going to plug it in.
For a level 2 charging you need a station which can be installed to your garage. A Level 2 charging station plugs into the car’s J1772 port, draws 240 volts with 16 or 30 amps current and can take the MiEV from 0 to full somewhere between 3-4 hours.
Last option is so called quick charging stations, sometimes called Level 3, which in Europe draw 400 volts with 32 amps. For plugs there are different standards, such as CHAdeMO, a standard developed and favored by the Japanese automakers. This type of chargers are the most common public charges. With MiEV, they allow to reach 80% capacity in 15 minutes, 50% in 10 minutes and 25% in 5 minutes. And the reason they generally only charge a car up to 80 percent is an intentional design to protect the battery, which can lose capacity from this type of charging. Note the change of charging cycle in the above graph when battery level reaches 80%.
Time your sessions
Your electric car likely has the ability to control at what time it charges. You can park the car, plug it in, but have the actual charging set for the middle of the night, when electricity rates are lower. However, as mentioned earlier the length of the charging time can varies, depending on battery level, as well as external temperature and the quality of the electricity output. Also with growing number of EVs, when more and more people are timing their electricity use to night hours the electricity rates can start to fluctuate in there also.
Therefore, you cannot always be sure that your car will have a fully charged battery in the morning with maximum range and ready to go. Even worse, you have no idea if this activity has saved you any money.
The most electric vehicle owners we have questioned are using their cars to go to work every morning and when returning to home they can’t be bothered and just plug in the vehicle at once. With simple calculation we can show how much difference a timed charging can make.
Let’s compare two different situations.
We will use the historic Nord Pool Spot (NPS) price data for Finland. In the first one the car is plugged in at 17.00 (yellow), and a second when the charging is timed form 23.00 to 05.00 (green). Times shown are in CET as they are displayed in NPS. The prices are shown in EUR/MWh. We’ll assume that the battery level, external conditions and therefore length of charge is same for both situations.
From the test graphs above we can see that during a the first part of charging session MiEV uses roughly 2,1 kW per hour and on the last hour while it charges from 80% to full, it uses average 0.9 kWh of power.
So, a quick calculation will show that the total electricity cost of one charging session in the first case is 35 cents and on the second 21 cents. That is roughly 40% difference.
Then we have to bear in mind the network tariffs. Dependent on your contract, this can vary. For the use-case explored here, the day time tariff is 5 cents/kWh and night time is 2,9 cents/kWh. Adding this to the calculation, we see that in first case the tariff cost is 57 cents and in second case it is 33 cents. A difference of roughly 60%.
Now, when the car is being used 250 days a year, the yearly cost would add up to 230 euros in the first solution and to a 135 euros. Being smart will save you close to 100 euros in a year. Think, how far can you drive with that extra money.
SLS electric vehicle optimization
This is just one example how SLS optimization platform can be used. If you are a supplier of e-vehicle technology or just a owner of an electric car, get in touch and we will see what we can do for you!