Interview: A solar power plant to drive cleaner electric cars


Interview: A solar power plant to drive cleaner electric cars
Written by madishthestylebar

Our Alsatian reader Fabien wanted to get rid of nuclear power to drive an electric car. He made the choice of a self-consumption solar installation on the roof of his house. After 5 years of production, it draws a very positive balance sheet.

Tesla Model S + Volkswagen e-Golf

Now regional manager of the Tesla Owners Club France, Fabien switched to electric cars in 2016, after following the adventures of Yoann, the founder of our webzine Clean Automotive.

Our reader started with a Hyundai Ioniq which allowed him to confirm his choice of electromobility. Two years later, the arrival of a child in the home made him decide to lease a Tesla Model S 75D. A Volkswagen e-Golf took over from the Korean electric car, becoming the second vehicle in a family that now numbers 5 people in total.

However, its eco-citizen approach does not stop at the abandonment of thermal engines well before the deadline set by national and European institutions.

A 4.2 kW peak installation

It is a set of reasons that led Fabien to have 4.2 kWp of solar panels installed on the roof of his house. ” I wanted to produce my electricity, not consume too much on the network. Above all, I wanted to avoid being told: “You drive electric, therefore you drive nuclear”. I could thus answer: “No, no, I am the producer of my electricity” “explained Fabien to Max Freyss.

In our reader’s garage, the left wall is impressively outfitted. Between the Tesla wallbox and the electrical panel of the house there is a lightning protection box specific to the photovoltaic installation and a two-way AC/DC hybrid Solax Power inverter. The latter is sized to accept up to 5 kWp of solar panels.

Right below it is an LG NMC (nickel-manganese-cobalt) lithium-ion battery with a gross energy capacity of 6.5 kWh. A value close to the energy consumed by our reader’s electric car for his daily trips. The kit is completed with a measurement unit which provides the inverter with information on the electricity consumption of the house.

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Operation in summer…

When the consumption of the house is greater than the solar production, the battery makes the difference. Originally, the latter was intended to store the energy produced during the day to recharge the car in the evening, when returning from work. ” Since then, there has been a pandemic, confinement, with still telework today “recalled Fabien.

This change in lifestyle allows our reader to recharge his electric car directly during the hours of photovoltaic production. The NMC pack, however, has not become useless. First of all because it will be used to power other equipment and to provide, in the best case, until the next morning, the energy necessary for the operation of the house.

The optimal period for this operation is the one in which we are currently, when the days are long, the sun is there in the morning very early until the evening very late. “, specified our interviewee.

… and in winter

In winter, the battery is too small to additionally supply the heating. In addition, solar production is down. ” In this case, I can decide to recharge the battery at night during off-peak hours, with a return of energy during the day. It’s a completely different mode of operation. I do this every year for 3 to 4 months “explained Fabien.

For the moment, our reader never resells his production. ” In 2017, it was not allowed with panels superimposed on the roofs, on a metal frame, without removing the tiles. The law has evolved. It is now possible to resell with such an installation “, he completed. What the Alsatian electromobilist has not done so far.

If he wished, he would just have to approach his energy supplier Électricité de Strasbourg, on which his department depends. Optimizing the operation of his installation as well as possible in all seasons, he does not feel the need for it at the moment.

A return on investment in 10 years?

Five years ago, the installation carried out at Fabien mobilized an envelope of approximately 20,000 euros. ” In 2017, I had calculated a payback after 12 years based on an increase in the price of electricity of 5% per year. In February, we had a very big rate increase. The situation should continue. My new calculations bring the break-even point back to 10 years, i.e. in 5 years “, he encrypted.

Today, the price of installations is falling, that of electricity is increasing. It got even more interesting “, he put forward. Our interlocutor estimates that the second-generation, monocrystalline panels, which are attached to its roof, can be used for about twenty years. ” Even if tomorrow they only produce 60% of their original value, they will still be there and will have been profitable. It will not necessarily be useful to replace them at this time. “, he assured.

Until now, he relies on rainwater to wash these surfaces. Even when the sand of the Sahara came to cover them, harming electricity production. He leaves ” to industrial solar farms that need profitability » costly cleaning with mineral water using a dedicated device. ” Individuals rarely do maintenance on their rooftop installations “, he argued.

Read also
Will new nuclear power plants be needed for the electric car?

Small annual report

With the Tesla Model S, Fabien drives about 20,000 km per year. The e-Golf totals half as much: 10,000 km. That is a total of 30,000 km each year in electric cars. This represents a consumption of 5,000 kWh, or an average of 16.6 kWh per 100 km. ” As luck would have it, these 5,000 kWh also represent exactly my annual solar production “, he approached.

The battery of the solar installation can be recharged several times during the day “, he clarified. This means that the daily photovoltaic production is not strictly limited by the level of the energy capacity of the pack.

When the weather is cloudy, the yield is necessarily reduced, without being zero however. Before covering the roof of your house with solar panels, it is necessary to make an estimate that will take into account this point, the sunshine of the site, as well as the inclination and orientation of the roof. Requirements in terms of production level will then result in the quantification of the number of panels required.

Charging test

With its inverter, Solax Power provides a smartphone app. During the visit of Max Freyss, the production of electricity was surplus (power of 3.2 kW). In addition to covering the low needs of the house (0.260 kW) and finishing recharging the buffer battery (almost 2.5 kW), a share was injected free of charge into the network at a modest power of 360 W.

Hence Fabien’s idea of ​​plugging our journalist’s Model 3 into the Tesla Wall Connector. The car system quickly indicated a power of the order of 4 kW (5 A on each of the 3 phases of the three-phase installation). The application showed the evolution of flows. First of all the suppression of the injection on the network.

The power required for the house, including the charging station, soared to just over 3.8 kW, provided mainly by solar production (3.2 kW), but also by drawing on the battery (more of 0.7kW). ” This is how you can demonstrate the possibility of recharging your electric car with your own photovoltaic installation. “, Illustrated our reader.

A history makes it possible to find the evolution of the figures over a given range. This makes it possible, for example, to observe that the passage of a cloud can result in a request for additional energy drawn from the network.

Why not do the same?

With an optimistic hindsight of 5 years, Fabien can only invite us to follow his example. ” Because of the assessment that I draw from my own experience, I would be wrong not to advise doing the same. Opting for such an installation has a cost. If the drivers of electric vehicles can be producers of their electricity, that is a step in the right direction. And for the car, and for the future. Because we need to obtain energy other than by oil, coal and nuclear “, he campaigned.

If it takes space for that, it still reassures somewhat in conclusion: ” In self-consumption, simply with a carport, a small car park, or a wall, you can already install 3 panels and produce electricity. So let’s go ! “.

The whole team ofClean Automotive warmly thank Fabien for his welcome and his testimony.

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