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The basics Converter Modules Mounting systems Mounting milestones Quizz
Is the photovoltaic energy valid and reliable enough for the north of France?    Which maintenance requires a photovoltaic installation?
What is a photovoltaic system?   What about the necessity of a regular cleaning of the glasses?
Which interest to send back to the grid the electricity produced by the PV Panels instead of storing it within local batteries?    What is the resistance of PV panels to hail?
What is the life time of a photovoltaic system?    What about the lightening risks?
How to get the best benefit from the Feed in Tariff?    Which hazards created by the electromagnetic fields of a solar farm?
 What are the external costs of photovoltaic electricity?    What is the contribution of solar photovoltaic energy to the world industry?
 What is the ecological impact of the photovoltaic energy?    Do panels contain hazardous substances?
 Are the Photovoltaic panels recycled? Capable to be recycled?    Is the photovoltaic energy powerful enough to supply the world needs ?
What is a photovoltaic system?
A photovoltaic system represents the addition of several components producing electricity using the energy of the solar radiations. The components of a PV (Photovoltaic) system are called PV modules, these modules having in charge the collection of the radiations, and its transformation into DC electricity. The conversion of the solar energy directly into electricity is performed through a semi-conductor material (Silicon as an example). This energy transformation requires no moving pieces, no combustion, and hopefully no noise. The elementary element of the production chain is called the photovoltaic cell : under the exposure of a light radiation, this cell is capable to absorb the energy of the photons. Several cells are connected together as a serial within a module. Photons collected by the cells are producing electrons movements within the different layers of a cell and enable a Direct Current ( DC ) production. This current is recovered through cables connected to the two faces of the panel.

The tension of the current produced at the outlet of a unique cell is weak: 0.6 V . This is the reason of the connection in series of the cells to reach generally a few dozens of Volt level for a panel as a whole.

To create a module, the cells are encapsulated between a glass sheet on the front face and other materials, water tight notably, on the backside. According to the technologies and the final purpose of the customers, modules are reaching areas of 0.1 m2 ( 10 W ) up to 1 m2 ( 100 W ) or more. Tension levels are varying from 12 V, 24 V and up to 48 V. [source: ADEME]

Is the photovoltaic energy valid and reliable enough for the north of France?

Even if of course it is more interesting for an electricity production perspective to install PV panels on the French Riviera (...), the yield of production is high enough in the North regions of Paris to enable the installation of PV panels: the production ratio is of 1.4 between Dunkerque and Montpellier with the same installation.

Which interest to send back to the grid the electricity produced by the PV Panels instead of storing it within local batteries?
On environmental and ecological standpoints the use of a connection to the grid avoids the necessity of batteries, which contain many pollutants ( acid /lead ) and whose life duration is limited to 7 or 8 years. Moreover, a system connected to the network allows to continuously recover the electricity produced while with batteries and when they are "full of energy", the corresponding energy from the panels needs to be evacuated. Batteries are accordingly used for very special applications and special sites which are far away from any connection to the grid, like mountains habitations or villages in countries under development missing from a sufficient electrical transport network.

What is the life time of a photovoltaic system?
Suppliers like Q-Cells are nowadays guarantying their product for duration time between 20 to 25 years with yields about 90 % of their original value after ten years, and 80 % after 20 years. Practically speaking and even if we still miss from numerous enough experimental feedback, a PV installation can be operational with sufficient yields recovery, for more than 30 years: this is particularly true with multi and mono crystalline cells.

How to get the best benefit from the Feed in Tariff?
Rooftop installations especially are here concerned: the bonus recovered (27 cts €/kWh) allows indeed receiving the most important tariff. This bonus is given in France, only if the PV installation is completely dedicated, in parallel with the electricity production, to the tightness of the roof and dependently from the building structure. The final selling price of the electricity is in this case about 60 cts €/kWh. If as an example the panels are just installed ON the roof without any tightness characteristics, the selling price drops to 33 cts €/kWh (identical with the conditions established for solar farms).

Which maintenance requires a photovoltaic installation?
Probably one of the most important quality of the PV panel: they ask for a minimum maintenance. Panels contain indeed in most cases, no moving pieces, and no solvents neither particular transitory or difficult conditions which could affect the life time of the different components.
It is recommended to check regularly the production yield to detect as quickly as possible some potential defects. Converters are probably the most critical pieces, with life time duration classically comprised between 10 to 15 years.

What about the necessity of a regular cleaning of the glasses?
Generally speaking, normal rain waters are sufficiently cleaning the surfaces for a proper behavior of the installation. For some particular regions and where specific conditions are observed (dust, pollution, industrial areas etc...) more frequent cleaning can be required.

What is the resistance of PV panels to hail?
The PV panels are properly protected against the potential damages which could be created from the hail. The glass used within the panels is tested and capable to resist to impacts of ice spheres having 1,25 to 0,75 cm of diameter and a speed of 140 km/h. As a summary the probability to damage panels through natural weather usual conditions is almost 0.

What about the lightening risks?
A lightening stroke can indeed destroy partly or totally a PV installation, so this is a very sensitive point within insurances contracts. But the solar installation doesn't at all increase the probability for a lightening stroke to occur on the buildings or facilities in the vicinity of a solar farm. As required by usual electrical standards & procedures, converters and solar regulators are equipped with lightening protections to keep adequate the PV installations.

Which hazards created by the electromagnetic fields of a solar farm?
The potential emitters of radiations are solar modules, connections lines, converters and generators. All the Direct Current (DC) producers, that is to say the panels, cells and connection lines are very weak radiation emitters : much less than most of the domestic electronic devices or electrical plugs we are familiar with. The single pieces of a solar farm where alternative current (AC) is used and could create radiations are Converters. For this purpose, they are installed within Faraday boxes.

What are the external costs of photovoltaic electricity?
It is true that during the life cycle of a PV system, we can observe some pollutions indeed produced during the fabrication of the different components used. These "external costs" are corresponding in currency terms to the sanitary and environmental impacts of their pollution. Currently the external cost of PV installations is estimated to 0,0015 € by kWh in South Europe, comparable to those of the wind route, and anyway much less important than the criteria met with usual fossil fuels energy suppliers ( gas, coal, oil, ...).

The figure here attached shows the current external costs of the PV systems installed in Central Europe and south of Europe when compared with other sources for electricity production. The highest value indicated is got from silicon cells, the lowest data from "thin films " using CdTe. It is here clearly stated that external costs are 10 to 40 times more important than for photovoltaic. [source: European platform of the photovoltaic industry]

What is the contribution of solar photovoltaic energy to the world industry?
During 2006, more than 50 000 persons across the world found a qualified job in the photovoltaic industry. The business of this energy counts about 10 billions € of turn-over in 2006. This high tech with a very promising future is already creating new jobs by thousands. The solar PV is among the business which is developing itself at the highest rate, with an increase rate of 35 % a year on average during the last decade. If we take the assumption of future rates of "only" 25 % in the coming years, this industry will have passed the semi-conducting business before 2030 with a yearly turn-over of 175 billions € at that date.

The photovoltaic industry is currently investing massively in new production capacities, and the size of the facilities is moving from low to medium scale plants toward huge production units. PV solar business is nowadays recognized by several first class financial analysts as one of the future most promising industry.
[source: plateforme européenne de l'industrie photovoltaïque]

What is the ecological impact of the photovoltaic energy?
The production of photovoltaic cells and modules requires a relatively important amount of energy. The EPBT (Energy Pay Back Time), is one of the smartest ways to qualify this fact: the EPBT calculates the ratio between the energy required for the cells production compared to the electricity delivered during the production life of the panels. In France on average and with Silicon multi-crystalline modules, the panels produce about 10 times more PV electricity than the equivalent energy requirements for their fabrication.

Another interesting result is the level of Greenhouse effect contained in the energy, according to the production source:

C02 emissions for one PV kWh are more important than for nuclear power and wind farms. These emissions are however linked to the energy sources used for the production of the different components involved in cells and a panel, which can come mainly from stock energies like in Germany or hydropower like in Norway with hydro power stations. To be noticed anyway that the 8 gr of CO2 by kWh indicated for the nuclear energy are taking into account only the uranium production part (source SFEN), within the same assumptions, photovoltaic CO2 level would have been of 0 gr by kWh knowing that the sun production involved no CO2 emissions on earth.

As a conclusion, a photovoltaic installation is producing no CO2 during the whole operating time, unlike other stock energies or uranium do. Solar energy availability has no limit, is totally renewable and without any futile emissions (neither noise nor pollution ). It's also a smart way to produce the electricity close to the consumption centers, minimizing by this the losses which occur through the electrical lines… the French national Grid operator, RTE, is also the first French electricity consumer through the losses observed within the network...

Do panels contain hazardous substances?
The photovoltaic technology is mainly based on silicon, second element present in the earth composition by order of appearance. Silicon as used in the PV industry is a non toxic element. In the past it was especially produced as a co-product from the electronic industries, but since 2005 the volumes concerned in the PV industry are more important than those involved within electronic applications. The future seems to orientate the efforts toward thinner layer of Silicon (80µm instead of 300 µm), and less pure so less expensive materials (20-30 €/kg instead of 50 to 60 nowadays). Amorphous silicon also should progress with heavy production capacities involved in the so-called thin films technologies.

Some technologies are using toxic substances like Cadmium (CdTe), selenium (CIGS), arsenic (GaAs) and lead (mono-Si and multi-Si, present currently in all the domestic electronic tools). These elements can cause severe environmental issues during their production, operating times and final recycling. Other technologies use no (or very few) toxic elements like amorphous silicon (despite some phosphorous compounds necessary for doping applications but quantities are very weak), a-SiGe cells, Graëtzel's cells and the mono-SI / multi-Si cells if lead can be avoided.

Q-Cells expect to produce lead free panels using mono-Si and multi-Si cells in the coming 5 years, providing accordingly with the Silicon technology, the best ecological source of the photovoltaic availabilities.

Are the Photovoltaic panels recycled? Capable to be recycled?
When the panels are reaching the end of their production life, the materials can be reused, for the most part of them, to produce again PV panels, especially if they are made of Silicon. The panels are treated by specialized companies, which recover Silicon, for new purposes. The recycling ratio varies according to the nature of the product and the raw material of the panels, that is to say Silicon, or not. The recycling ratio is varying according to the materials used, but in the case of Silicon cells, it can reach up to 90%:

  Kg/m2 Weight % recycling
ratio (%)
Glass 10.0 74.16 90
Aluminium 1.39 10.3 100
Photovoltaic Cells 0.47 3.48 90
EVA (vinyl acetate),
Tedlar (PolyVinylFluoride)
1.37 10.15 -
Ribbons 0.10 0.75 95
Glue,... 0.16 1.16 -

Composition of a solar crystalline module and the quantities/ratio recovered through the recycling process [Source: Light cycle: Recycling PV materials - David Appleyard, associate editor, Renewable Energy World Magazine [UK], april, 2009]

The companies member of the PV Cycle association (international association for the promotion of the PV panels recycling) signed an vonluntary agreement on December 19th, 2008 which set the target of a minimum 65 % recovery of the PV panels and a minimum recycling ratio of 85 %.

Is the photovoltaic energy powerful enough to supply the world needs?
Theoretically speaking, it would be necessary to capture only 0.01 % of the sun energy received by the earth each year to cover the annual requirements in energy of the whole humanity.
As an example, only 5 squares of 360 km2 would be necessary to supply the global 20,000 TWh energy consumption of the world each year.
For the comparison, France is consuming each year 600 Terawatts hour of energy globally speaking, that is to say coal, nuclear power, hydro, oil and gas, etc: the same calculation indicates that 12000 km2 or 2 % of the global surface of the country could supply the energy needs, having taken into account only 1500 hrs of sun a year on average.

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