Looking at the physics, solar is complementary to electric mobility, particularly in certain use cases like day charging at work places or combined with battery capacity at home. Solar has a predictable generation curve and produces electricity during the day. This PV generation curve matches well with the time at which the majority of electric vehicles are parked and can be charged, for instance at workplaces or public parking – a match that can be optimised with smart charging devices. Solar generation also matches perfectly the load curve of trains, trams or metros that run and consume energy during the day, making them good candidates for solar consumption. Finally, recent surveys show that solar is the most popular source of energy and can support the public acceptance for sustainable transport policies. In Europe, solar has the highest level of support among citizens.9 Solar empowers consumers to invest into their own energy transition and gives them a sense of independence. As a result, one can easily observe the mutually reinforced dynamic between solar energy and electromobility: a recent survey by EuPD Research on electric-mobility has shown that for 77% of the respondents, the main reason to purchase an electric car was to charge it using their own solar energy, making it the most important motivator for purchase.
Solar and mobility: A perfect match
With this perspective in mind, Solar Mobility refers to all the use cases where
solar energy powers electric mobility – either directly, or through innovative
supply solutions, or smart charging.Solar presents itself as an ideal companion for clean mobility. With falling costs over the past years, it is a competitive and fully sustinable electric ‘fuel’. It is also modular and can thus be installed close to electric mobility infrastructure. It presents synergies between its generation curve and the daytime charging process of vehicles. Perhaps the most significant benefit of solar to electric mobility is that it is a popular source of energy that can be owned by consumers. A recent survey by EuPD Research found that for
77% of respondents, the principal reason to purchase an electric car was the ability to charge on their own PV production.
Mapping the use cases and learning from experience
The Solar Mobility Report presents the world’s first mapping of use cases regarding
solar in mobility. This mapping is based on a catalogue of existing research, pilot
projects, and business cases. The report summarises the lessons learnt from these
experiences, providing an overview of the benefits and challenges of each model.
Three main types of solar mobility models are distinguised: solar-powered
mobility, vehicle-integrated PV, and smart solar charging.
Choosing solar as fuel: solar-powered mobility
Solar-powered mobility refers to models where solar electricity is used directly or indirectly to ‘fuel’ clean mobility. Various models exist and offer different options for particular transport cases.
Driving on the sun: Vehicle-Integrated
Photovoltaics Vehicle-Integrated Photovoltaics (VIPV) are solutions where a clean vehicle is equipped with directlyintegrated PV cells. The term and the technologies come from Building-Integrated Photovoltaics (BIPV), a group of solar technologies where PV cells replace
conventional building materials. In recent years, thanks to the falling cost of solar cells and improvement in cell integration, VIPV vehicles have been deployed in the market, offering a clean and affordable alternative.
As electric vehicles still have a high purchasing cost, the competitiveness of the fuel –
electricity – is key to supporting the shift to electric vehicles by enabling a low operating cost. This is were solar offers a good opportunity: solar PV energy is already cheaper than grid electricity costs in a large number of countries, and its cost is only decreasing with time. It is an
unlimited resource, available domestically, thereby reducing the dependence on fuel imports from foreign countries.
On-site solar supply
Solar PV is an affordable technology with a high degree of flexibility and scalability. It can be installed at the closest of consumption points, guaranteeing a direct and fully renewable electricity supply to electromobility infrastructures. The “electric mobility environment” provides many types of passive surfaces – such as carports, parking roofs or rail companies’ land – which can be used to deploy on-site solar charging solutions.
Solar charging stations
Standalone charging stations, such as public charging stations in cities or on the highway, can be equipped with a solar system. Most of the time, the solar panels are integrated into a solar canopy covering the vehicles parked at the charging station.
CASE STUDY INNOGY DUISBURG SOLAR FAST CHARGING STATIONS
The German energy company innogy has launched its first semi-autonomous fast charging station, located in the German city of Duisburg, in a rest area off the A42 and A59 highways. The 150 kW fast charging station is equipped with a 180 m2 27.5 kW solar rooftop and a 210 kWh battery storage facility. The project is a result of innogy’s research and development teams.The battery storage minimises the pressure on the electricity grid by buffering peak load periods with green electricity from the solar panel when several vehicles are using ultra-fast chargers on full power at the same time. In addition, it maximises the use of the solar electricity which can be stored when vehicles are not charging or the sun is not shining: the charging station can even operate completely off-grid at times. When solar power
is not available, grid green power is sourced to supply the additionally needed kWh.
While the local grid capacity is often not sufficient to connect the fast charging station, with this innovative project, innogy facilitates the integration of a fast charging station into the grid with green electricity.
The adoption of on-site solar charging solutions may be hampered by the capital cost of investment in solar charging stations, where the installation of the solar system and possible battery storage add to the investment cost of the electric charging stations.
Building-integrated solar charging solutions
Building-integrated solar charging solutions refer to models where the charging solution is connected to a building equipped with rooftop solar. It is increasingly successful, partly driven by high demand from building owners in the private sector.
This model provides important economic benefits to the EV driver, following the logic of self-consumption. Maximising the charging on the self-generating energy lowers the energy costs by saving on the energy component of the bill, the grid tariffs and the energy taxes. In addition, bundled offers are being developed, where the installation time and costs of the charging station and the solar system are combined.
Off-site solar sourcing
Using solar to run electric vehicles does not necessarily require an on-site solar installation, thus solutions exist for those consumers that cannot deploy a direct connection to a solar installation. Such solutions are referred to as ‘offsite solar sourcing’. In this model, solar electricity is produced at different points of the grid but is commercially supplied to the electromobility consumer through innovative supply contracts. The solar electricity is traced
from the moment of generation to the consumption by the end consumer through Guarantees of Origin.
Utility green procurement
Utility green procurement allows an EV owner or the charging operator to purchase solar electricity via ‘green premium products’ or via a tailored renewable electricity contract, such as ‘green tariffs’ offered by an electricity provider.
Power purchase agreements
A power purchase agreement (PPA) is a long-term power purchase contract between a power consumer (EV owner, charging station operator) and an independent power producer (utility or a financier). As part of this agreement, the consumer commits to purchase a specific amount of solar electricity, or all the electricity generated by a solar installation, at a price per kWh agreed in advance. The PPA is bundled with a specific solar installation, and therefore they ensure direct ‘solar mobility offers’, which run over a certain period of time, typically 10-20 years. There are various models of PPAs, which can be tailored to meet the buyer’s needs.
SMART SOLAR CHARGING
The additional electricity demand induced by EVs in a large-scale rollout scenario by 2035 is estimated to lead to an average increase of 0.5% in electricity demand per year, while the annual growth of electricity consumption has amounted to 1.3% per year since 1990.26 However, natural charging behaviours, if they remain unchanged and similar to conventional fuel charging (5-minute charging, independent of the time), can contribute to increased existing peak loads (typically at night when drivers will come home and charge their electric vehicles). In addition, these new loads, connected to the low voltage grid, can create new congestion challenges on local distribution grids that will accelerate the grid’s ageing or lead to service interruptions. Ultimately, the connection of charging stations could simply be refused due to the lack of adaptation of the grid or could come at a high cost for the consumer.
Santa Clara Valley Transportation Authority (CA, USA) is piloting, since 2019, a cutting-edge solution that manage operation, charging and energy consumption of electric buses while reducing the impact on the State electricity grid. The goal is to maximize the efficiency of the charging through a smart charging process that takes into account the cost of electricity and the cost of demand peaks charges from the public utility.
VEHICLE-INTEGRATED PHOTOVOLTAICS:SOLAR-POWERED VEHICLES
It has long been a dream of the transport sector to integrate solar panels onto the body of the vehicle (particularly on the roof, but also on the side panels and bonnet) to directly power the electric motor and/or other features such as heating and cooling. High-performance solar cells have long been used to power spacecrafts through their journeys in outer space, and now, thanks to technological improvements, cost reduction of solar modules, and the increased electrification of transport, solar-powered vehicles are ready to launch on Earth.
Beginning with the first Tour de Sol competition in Switzerland in 1985, solar cars have had their own races that saw engineers compete in order to innovatively combine solar and automotive technologies. The very well-known World Solar Challenge in Australia is a race
across the 3,000 kilometres separating Darwin from Adelaide, where solar vehicles compete in terms of speed, efficiency, and practicality.
Solar trucks and buses
Besides individual mobility, PV can also be installed on other vehicles, such as trucks or buses. The placement of solar cells on heavy-duty vehicles has been an object of research in the past years, including by the private research organisation Tecnalia and the research institute Fraunhofer Institute. Since the roof area of trucks is generally larger than a smaller car, and has no curves, the installation of PV is in fact less challenging.While trucks are unlikely to be able to be powered exclusively by solar generation due to their heavy weight and significant power needs, the surface area of the roof has the potential to accommodate solar systems large
enough to power certain features.
The maritime sector is a large greenhouse gas emitter, with around 940 million tonnes of CO2 emitted annually. It also contributes to air pollution, particularly in port and coastal cities, and noise pollution.
The list of solar-powered vehicles would not be complete without mentioning solar rooftop trains. Examples of solar-powered trains can be found particularly in countries with high irradiation levels. The solar systems are not used for traction power, but rather to supply auxiliary services such as lighting, fans, and air-conditioning systems. The large rooftop surfaces of the carriages can be used to install these solar systems.
Solar airplane transportation
Accounting for approximately 3% of global CO2 emissions,41 diverting aviation from fossil fuels is crucial in order to achieve the decarbonisation of the transport sector. This will be a major challenge as the sector is expected to rapidly expand in the coming years, with its
emissions doubling or even tripling by 2050.
Source:SOLAR POWER EUROPE
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