On the sunny side
Audi manager Bernd Ritter lives with his family of three around 25 minutes’ drive from the Audi Forum in Ingolstadt. As you approach his house, there’s one thing you notice right away: solar panels on the roof. It’s part of a private modernisation project which extended over several years. The engineer spent around €73,000 on having a household power plant installed in four stages. It began in 2014 and currently consists of solar cells with a power output of 15.5 kilowatt peak (kWp) on the roof and two batteries in the cellar with a total capacity of 27.6 kilowatt hours (kWh). “The sun is always there and has enough power to supply us with the energy we need. Why shouldn’t we use it? I do realise I’m in the fortunate position of being able to afford a household power plant. Other people might spend that kind of money on a sports car, but to me, this project is more exciting. It’s important to me to do my part in helping energy move towards renewable sources.”
Sun electricity for vehicles
Thanks to their household power plant, the family can supply home-produced electricity to the house and their vehicles, which until recently included an Audi Q7 e-tron quattro. “The Audi Q7 e-tron quattro was a great experience and loads of fun to drive.” Mr Ritter drives a plug-in-hybrid instead – the Audi A3 Sportback e-tron – as well as a fully electric vehicle, the VW e-Up! . Photovoltaic system, batteries and electric mobility – it’s still a rare combination, but that could soon change.
The example he has set outside Ingolstadt shows how the elements in this kind of modern concept intertwine: the household power plant is augmented by charging devices for the Audi vehicles. Charging is easy and convenient thanks to a specially installed industrial power socket and the Audi Wallbox that goes with it. The vehicles’ batteries are charged up overnight – using solar power produced during the day, naturally.
The charging station knows when batteries are full and automatically stops the charging process. An Audi A3 Sportback e-tron needs around 3.5 hours to charge fully using a regular domestic socket, and around 2.5 hours using an industrial one.
The Audi Q7 e-tron quattro:
The world’s first plug-in-hybrid model with a six-cylinder TDI engine and quattro drive has been available in most European markets since mid-2016. The Audi Q7 e-tron quattro combines the benefits of electric driving with those of the combustion engine. It accelerates from zero to 100 km/h in 6.2 seconds and consumes 1.9 litres of diesel per 100 kilometres (combined NEDC).
- electric mode up to 56 km // 275 kW (373 PS) // 700 Nm
“The household power plant’s battery discharges during the night if the power’s needed for things like household appliances – fridge and washing machine, for instance – and for charging the cars. As soon as the sun starts shining again in the morning, the household power plant’s battery charges up again,” says Ritter. How much solar power is generated depends of course on the weather and season. Top figures are usually achieved in the summer in Germany. Another factor comes into play at the Ritter family home, as Bernd Ritter explains: “Our house is very well positioned. Its roof pitch faces an ideal south, so we get a very good energy yield.” Sometimes more electricity is produced than the family needs for everyday use. When that happens, surplus power is fed into the mains and sold to the power company. Selling may be an important economic aspect of amortisation, but his family doesn’t have to worry about being plunged into darkness, because the system is programmed intelligently. “The system follows the following supply rules: number one priority is supplying the house including charging the vehicles. Priority two is charging the battery in the cellar. Lastly, any surplus electricity produced is sold. In other words, “Only if the house and the cars are supplied are the batteries charged up in the cellar, and only once the battery is charged is electricity sold,” says Ritter.
Fascination electrical driving
Bernd Ritter is currently the project manager of a forthcoming Audi e-tron model and has worked at Audi for the past 20 years. A degree dissertation enabled him to join the development/electrical business unit. His career has since been shaped by vehicles that showcase the benefits of electric driving. The trained engineer takes his passion for his work home with him. As it stands, plug-in hybrid vehicles are ideal for his family’s needs. For him, range and a good charging infrastructure are they key to a future in which cars are powered by electricity alone.
But because of the weather where he lives, things aren’t always quite so sunny for Bernd Ritter and his household power plant. In winter, when the days get shorter and the skies are often cloudy and even full of snow, power yields can drop because of a lack of sun. The system responds appropriately by connecting to the mains and obtaining ‘outside power’ to cover lean periods before a deficit occurs. Bernd Ritter can use his battery manufacturer's customer website to analyse when his household and vehicles are being supplied with solar power – surfing on the green wave, as it were – and when electricity has to be bought. “I’m interested in the statistics, of course – per day, per month, per year. Consumption and production are really easy to track this way. Yesterday for instance, I didn’t need any extra electricity, I was 99% autonomous. The system has to tune in now and again because of the frequencies, so it’s normal to miss a percent or two,” says Ritter. “Ah, take a look here: here you can see that my wife came home and charged the Audi A3 Sportback e-tron 2.” So it’s not just the bigger picture you can examine, it’s the details, all the way to a map showing other owners of household power plants made by the same supplier as the Ritter family’s, with mini-profiles – but only if they’ve agreed to share their data. It would be going a bit far to describe it as a contest, but Ritter’s voice does carry just a touch of pride when he clicks on the list: “I’m the biggest solar power producer here in our area.”
The Audi A3 Sportback e-tron:
This premium compact car with a plug-in hybrid drive system offers unlimited everyday capability. It unites the strengths of its electric drive system with the benefits of a combustion engine and combines electric driving with high range thanks to its powerful four-cylinder unit. It can drive for up to 50 kilometres in electric mode under NEDC.
Home is naturally a fixed point within this self-made energy supply world, but travelling and being mobile is a major part of family life too. So being able to charge up at your own property is a key to the benefits of electric mobility. The Audi A3 Sportback e-tron can cover up to 50 kilometres in electric mode, while the Audi Q7 e-tron quattro manages up to 56 kilometres.
“I drive an average of 20 kilometres a day, for which I charge up at home and at work,” Bernd Ritter says. It’s a range that allows him to commute without producing emissions locally using the electric mode of his e-tron. And without producing much noise either.
Save and rewin energy
“I don’t listen to the radio any more. Music’s great, but driving without any sound and no engine noise or vibration – just enjoying the peace and quiet – that’s another level,” he says. Ritter uses every possible charging opportunity whenever he stops, and he has enhanced his driving style to achieve his aim of driving as far as possible in electric mode. “If you want to make efficient use of the benefits of electric driving, you have to adjust your driving habits after driving a combustion engine. On my daily routes I know exactly where I can ease off the pedal and coast. The motor just turns off on its own accord.”
“Electric mobility is evolving bit by bit. It’s a gradual process and it can’t all work perfectly straight away. We’re going to see a lot of progress.”
This coasting, also called ‘sailing’, saves energy because the motor switches off. But there’s a way of actually getting energy back and it’s called ‘recuperation’. When you decelerate, the vehicle’s kinetic energy is no longer transformed purely into heat by the friction of the brakes. A lot of it is converted instead into electrical energy by the electric motor acting as a generator, charging the battery so that it can power the vehicle again. On longer journeys, Ritter uses the combustion engine in his plug-in hybrid vehicles. “Plug-in hybrid vehicles let me drive really energetically, however long the journey. Driving fast on the autobahn is great fun, but I have to say that for me, accelerating in town in electric mode is even better. It’s really remarkable.” The outstanding experience he has had driving these vehicles has only very occasionally been tarnished by things not going quite so smoothly. “Once we were on holiday and we couldn’t find the right connection to charge the car,” recalls the family man, and admits that “electric mobility is evolving bit by bit. It’s a gradual process and it can’t all work perfectly straight away. We’re going to see a lot of progress. Range and charging infrastructure are major factors. Audi’s forthcoming fully electric vehicle will be able to drive up to 500 kilometres, giving you more latitude, including on long journeys.”
Ritter concludes with a prediction for the future of mobility: “As far as purely electric vehicles are concerned, range will be a major factor alongside the fact that you’re producing no local emissions when you drive. I think there’s going to have to be a stronger focus on infrastructure in the next few years. You need a range of at least 400 kilometres, then you need at least one quick-charging station within that range. I’m already really looking forward to the moment Audi’s fully electric model becomes available.” The future of electric mobility remains an exciting topic and one thing is for sure: the Ritter family is already surfing ahead on the first wave.
Household power plant statistics
|10 kWp||power output|
|2 vehicles||Q7 e-tron quattro & A3 Sportback e-tron|
10,500 kWh total //
average 880 kWh per month
|average 710 kWh per month||Consumption|
|5.300 kWh||Mains feed|
|12 months||Time period|