“The energy comes from the sun for free – and there’s plenty of it.”

Jens Wolf / e-mobility

In this interview, Jens Wolf explains why combining electric mobility with photovoltaic technology is not only an option but a must for our future.

How did you land on this topic?

By now it should be common knowledge that the world’s population needs to undergo a disruptive energy transformation if it wants to achieve the climate protection targets to limit the rise in global temperature. The traffic sector can get us substantially closer to this goal by cutting down one third of the greenhouse gas emissions. The technology to achieve that is available. The market and the user simply have to be open to this and embrace it.

But why aren’t they?

The arguments that always come up are the high initial purchase price, the shortage of charging points and the low ranges. Starting in 2020, established car makers will offer vehicles on the market that feature ranges north of 400 km. But there are also new actors pushing into the marketplace that  are offering electric cars in the lower price segment. Fully re-charging your car at high-performance charging points will be possible within 30-40 minutes. This would – taking into account some reserves – allow ranges of almost 800 km with only one charging stop. And that cover 99% of all trips.


In Germany, the total of all vehicles is on average moved for 1 hour per day, crossing a distance – on average again  – of 36 km per vehicle. Statistically, for the remaining 23 hours of the day the cars is parked to then be charged with electric energy to cover a daily consumption of 6.2 kWhs. By the way, that amounts to an average of not even 300 W of continuous output. Contrary to the unwelcome scenario where all electric vehicle drivers charge their vehicles between 6 – 8 p.m. with 22 KWs, the German power grid could easily take on the total charging needs of all e-vehicles using intelligent demand management. This, of course, requires sufficient availability of AC charging points on every street corner, at your employer’s, at the shopping center and at home. Here we need IT technology to optimize grid and charging management. However, what is still missing is not only access to electricity at all places but also the extensive willingness of drivers to adapt to this new and different kind of mobility.

What does that mean exactly?

Planning your charging stops for longer trips is often a must and cannot be avoided – even with a more closely-knit network of charging points: You always charge your vehicle whenever you can (e.g. at home or at your place of work) and not only when you need the car. Plus, the driving speed has a much greater impact on the car’s range than with a combustion engine car – this requires the willingness to trade high speed for fewer charging stops. And in addition, we also have to do our homework as regards technological aspects, in particular the issue of battery capacity.

What kind of progress is to be expected in this field in the long and more immediate run?

Using larger batteries depends on research being successful in achieving a significant increase in performance density. Because it makes no sense to drive around in your neighborhood for 363 days a year with a ton worth of batteries and then go on vacation only once a year. Electric power, however, is the most noble form of energy: Electricity can be converted into mechanical energy (e.g. motion) and back at high efficiency. The conversion into chemical energy (e.g. hydrogen, batteries)  is achieved at lower but still sufficient efficiency. It can also be converted into thermal energy with only little loss  – to convert it back, however, is extremely wasteful.

Since the actual ecological footprint of e-mobility  is a subject of controversial debate at the moment: How “clean“ is it really?“

The electric energy used for e-mobility is only as clean as the primary energy used to generate that electricity from. Thus, an electric vehicle is CO2 neutral only if the electric power is not pulled from fossil resources. Unless that’s the case, the result is even worse than with a combustion engine due to conversion losses. If, however, the batterie is charged with solar, wind or hydroelectric power only, the ecological balance sheet looks good. In contrast to the combustion engine, here the users decide how much CO2 they emit by choosing the energy source. Now all that’s left for the battery producer is to ensure a sustainable extraction of raw materials and a production that is free of greenhouse gases to shrink the ecological footprint as much as possible upon delivery of the car.

How about hydrogen?

As a chemical carrier of energy, hydrogen supplements e-mobility. Being a “built-in charging station“, a fuel cell can charge the on-board battery while driving. That allows ranges of up to 1,000 km at a relatively moderate increase in weight. Right now, car models featuring hydrogen fuel cells are entering the market and so are the first facilities manufactured in series, available for producing, storing and reconversion of hydrogen for residential buildings.  This way energy can be stored throughout the year or used as fuel for hydrogen fuel cell vehicles.

You also mentioned solar power. Could that become a serious factor, in particular here in our regions?

The good news is that every day, a thousand times more energy shines on our planet than we consume. It’s up to us to use this energy. By now the purchase price for photovoltaic panels has dropped to a point where under certain conditions the electricity produced can compete with spot market prices for electric energy at the EEX without receiving any subsidies. We, however, need twice as many photovoltaic systems as are currently installed in Germany and also 30-50 % more wind power to achieve the desired energy transformation. Why doesn’t every house have its own PV installation?  Depending on the local situation, a 15 kWp PV system can cover the annual power needs for your home, your driving and your heat pump. Since your house produces more energy over the year than it consumes, the demand for primary energy becomes negative. The energy from the sun comes free – and in abundance. The only question that remains is what to do with all that energy once your own your power storage is full, the laundry done, and lunch is cooked.

What are the arguments against feeding power back into the grid?

Since the feed-in tariffs are going down, one can expect to turn only a small profit with this and so one should sell any surplus of renewable energy someplace else, at least for some time. At the moment the big utility companies have no interest in using this surplus energy, e.g. by electrolysis, since that would reduce the profitability of their remaining coal-fired power plants.

Are there any solutions to this problem available?

Along with an increase in market penetration by electric vehicles, new potential buyers for these amounts of electric power are going to show up (most cars are parked at lunch time anyway). So it would make sense, via community projects for example, to have the sellers of surplus energy meet up with those who need energy. That would not only make e-driving green but create a new market for all interested parties.  For this to happen it takes a somehow smarter charging point infrastructure in connection with an IT solution for managing and billing.

The hope is that such decentralized concepts are going to prevail in the market place as e-vehicles increase in numbers and also that legislators that at the moments are favoring the big electricity companies providers and power grid operators as essential entities remove the legal obstacles to self-marketing your surplus electricity.

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