Solar thermal energy analyzes in France

Mastering solar energy, solar thermal energy, how to take action?

Bernard REYNIER, Physical Engineer from the National Polytechnic Institute of Grenoble.

Keywords: solar, sun, energy, heat, weaknesses, optimization, development, storage, savings.

In general, the process is the following: the sun heats a fluid, which vehicle calories within habitats or industrial premises. The thermodynamic cycle can be reversed and produce cold, the sun is so used to cool the premises.


Energy is at the heart of our daily life; the exponential rise in the prices of fossil fuels and derived energies, the promulgation of the future energy law will have a significant impact on our energy consumption patterns.

All analysts are categorical, despite the significant potential of its sunny areas and its industrial capacities, France is lagging behind in the development of solar thermal energy as well as in the effectiveness of its energy management policy.
The debate is no longer to oppose so-called renewable energies to mass energies supplied by nuclear or fossil fuels. Everyone has understood that we will still need for a few decades of these necessary productions if only to maintain the balance of the electrical networks on days without wind and without sun ...

Indeed, our civilizations have no other credible alternatives on the horizon of the end of the century, which represents three to four generations of researchers who will know how to discover new sources of energy, let us be sure. In the meantime we have to react.

The late French

The country must engage in the implementation of an active approach of development of a pragmatic energy mix due to its economic realism… THERMAL SOLAR ENERGY has significant advantages; we must and can domesticate it.

It will be a long-term job, a project lasting several years in the current tense energy context. We still have to commit to it and give ourselves the means to achieve our ambitions.

The subject of solar thermal energy deserves to be clarified, with pedagogy. For the “lambda” citizen, thermal solar energy is too often associated on the one hand with the production of electricity under complex technical conditions and on the other hand with the idea of ​​costs which are always expensive.

For the general public, many elected officials, the association - SOLEIL - HOT WATER - HEATING OF DOMESTIC WATER - PARTIAL HEATING OF PREMISES - AIR CONDITIONING - is not immediate. It is enough to read the press articles within the framework of the debate on energy to measure the importance of the deficit of communication - comprehension within the media…

Few writings mention the average energy source attached to a 100 m² habitat. We talk about m² of sensors, costs, but almost never the energy potential in legal units readable and understandable by the greatest number.

Solar potential in France

For an individual housing of 100 m², equipped with 16 m² (8 m by 2) of flat collectors, the average annual deposit amounts to approximately 8800 KWh for the partial heating of the sanitary water, the water consumed by the household appliances, dishwasher, washing machine and partial heating of the habitat.
For a building type village hall, hotel, retirement home, the average annual potential is proportional to the surface area of ​​the sensors, which, in this type of structure, can be very large.
Finally, industries using hot fluids (all Agri-food, Paper industries, etc.) are very affected by this energy; with large roof surfaces, potentials of 50 - 000 kWh are common ...
To these deposits will be added, as soon as possible, the benefit of solar air conditioning, just as important ...

This reflection explains the conditions for developing the use of THERMAL SOLAR ENERGY and its consequences in:

- reduction of traditional energy consumption and greenhouse gas emissions,
- the reduction in financial expenditure of communities and citizens,
- the development of employment in noble professions, bringing social benefits,
- the implementation of an active pedagogy with citizens who need to be guided in the control of energy,
- the influence of France, which would make an effective and exemplary contribution to the less rich countries.

For years, the market and the offers of solar thermal installations have been like hen and egg. The market awaits the offers which await the market ... In the new construction market, 60 pavilions are likely to use solar thermal equipment. In addition to this flow, there are apartment buildings, tertiary accommodation buildings (hotels, retirement homes, etc.) and certain industrial buildings.
As for the home renovation sector and the replacement of obsolete devices and heating methods (electric water heaters, heating or air conditioning systems, etc.) their annual volume is four to eight times greater ... sold one and a half million electric water heaters in 2004 compared to ten thousand solar water heaters ...

The potential is commonly evaluated at 250 annual installations, compared to 000 sales in 10… The lower range of the average annual energy deposit is 000 GWh

The obstacles to the development of solar thermal energy in France

How to sell products that are not known? Media communication, reduced to the minimum, is too difficult for the general public to read. Consumers, used to “see and touch”, do not know the devices which are not presented by large DIY stores. The distribution is entrusted to several thousand craftsmen labeled "ADEME" whose solar thermal products are rarely predominant in their income. While you install yourself an electric water heater, a radiator, a fireplace, or even more complex equipment, it is almost impossible to acquire solar thermal equipment in a kit, thus prohibiting their self-installation!

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In the municipalities, in the industrial sector, during calls for tenders for the construction of hotels, retirement homes, few companies offer installations combined with solar thermal energy. When quotes exist, with regard to the technologies developed, the prices are high (or even excessive). Why, given comparable service, are solar equipment three to six times more expensive than conventional devices? The analysis of the value does not explain the price differential between an electric water heater and a solar thermal tank, ultimately not very innovative ...

The device is subject to tax rebates and the payment of premiums (Regional Council, etc.). This substantial “purchase + installation” aid hinders emulation and competition, and limits the offers of new manufacturers who are often discouraged when faced with the constraints of obtaining ad hoc labels. In addition, the weak market dynamics do not encourage manufacturers to join this activity.

Should we really continue with the policy of paying premiums? Or to encourage the production of materials at realistic prices by "opening" the market to new entrants?

The industrial and energy actors must now develop industrial and commercial combined actions, reversing this inhibiting and sclerosing cycle by offering “market prices”.

The steps to take

First: communicate differently and reduce costs.

The media communication must be improved, by implementing and television events in the regional press.
Should we impose such drastic standards on suppliers? Let's quickly free up the market. Solar energy being free, the CSTB should not legislate but assess only the efficiency of the installations without any other form of assessment. This in order to enlighten the buyer while positively stimulating the competition.

The sale price of the equipment should be included in a range of 700 Euros to 2000 Euros (today the lower range is higher than 1200 Euros). Do the installation costs deserve to be invoiced at the rate of a BTS labor?

Secondly, develop and industrialize innovations.

The challenges require reducing the return on investment time to 6-8 years as soon as possible compared to conventional energies. This realistic challenge will be solved by innovations reducing manufacturing costs and then by the growth in demand that will follow.

The research services of energy marketers can change the age of obsolete technologies used. New materials such as phase change, regulation electronics, can be infused with great interest in solar equipment technologies. FRANCE must undertake appropriate research in this field.

The European solar thermal sector today represents less than 10 jobs, of which barely 000 - 2% concern FRANCE. The research, manufacture, installation and maintenance of these devices present a source of thousands of high value-added jobs, attractive to our youth. The potential of one million jobs in Europe is often mentioned.

On the other hand, we obviously cannot abandon the manufacture of materials. We must help the creators of innovative productions. In regions where metallurgy, plastics, electronics and micromechanics industries are disappearing, skills could be recycled in these ways.

Finally, solar air conditioning must quickly be the subject of research for uses in tertiary premises, in particular accommodation premises and other retirement homes (which, following the 2003 heatwave, could be the subject of test actions. ), etc. Local authorities are the first customers interested in these means of comfort which have become necessary in a large part of their real estate stocks.

This old technology, industrially neglected (which did not know gas refrigerators when camping where with “hot we make cold”?), Nevertheless presents real challenges. The scorching summers to come, widely predicted by experts, will boost the installation of air conditioners with unfortunate consequences on summer electricity consumption, while the operating conditions of power plants will be far from their optimum.
Solar air conditioning will help resolve these difficulties. (Following the heatwave of 2003, the explosion in sales of air conditioners with poor performance must be contained without generating future difficulties both in the production - distribution of electrical energy in summer and in the rise in temperatures of the atmosphere and the worsening of greenhouse effects linked to the various effluents, etc.)

Train in energy management

The implementation of the policy of energy control and the development of the use of renewable energies requires the initiation at the same time of a major training policy in order to support the body of employees who will intervene on this long chain. valuable. The cultural transition will take place over several years during which it will be necessary to support this profound change. The list of areas impacted by this cultural inflection point proposed below for educational purposes cannot be exhaustive.

particularly include:

- Installation activities for thermal solar installations serving all buildings (including Industrial),
- Architects having to acquire new knowledge in heat exchange, sunshine, etc ...
- Design offices responsible for thermal studies in the construction and renovation of buildings,
- All the building trades which will use new materials (eg “Monomur” brick), solar floors, new roof coverings incorporating solar thermal or photovoltaic collectors,
- Engineering offices, experts in energy studies of industrial processes (necessarily complex and varied),
- The activities of installation, adjustment, maintenance of photovoltaic solar installations, in particular the protection devices for the couplings to the electrical distribution networks,
- The field of power electrical engineering for wind turbine generators or small hydraulic power plants, electrical coupling of electricity production facilities to EDF Distribution networks,
- Jobs in the transport sector: new engines, electronic regulations, etc.

The potential of training cycles and sites, of competent trainers in these relatively new fields where demand will be growing strongly, are today insufficient to meet the needs from 2008-2010.

At the same time, the significant retirements of the "baby boomers" will amplify the skills shortage.

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Thermodynamics, the laws of heat exchange and fluid circulation are relatively complex to acquire. They require heavy retraining when these skills are little used. Today, this knowledge is little distributed and mastered among professionals in the building or industry.

In the same way, the fields of power electronics, mechanical calculations necessary for the manufacture - maintenance of hydraulic or wind generators, are complex and not widely used in general training courses.

The same applies to the operating concepts of equipment such as heat pumps, the use of which will increase exponentially through air conditioning and reversible heating.

The solar business

Without a considerable effort to train craftsmen, the change from an annual rate of installation of 10 solar water heaters in 000 to a volume of 2004 by 200, ie a growth factor of 000, cannot be realistic. Especially since the success of the challenge will be linked to the professionalism of the craftsmen installers strongly impacted by the retirements of the “baby boomers”.

The increase in the maintenance needs of geothermal systems or heat pumps will require the training of new promotions of professionals, particularly in the maintenance sector.

The need for contractors will increase. It is they who on the one hand will guarantee the conformity of constructions with the rules and on the other hand will facilitate the migration of new concepts within the craft industry. These trades being at the origin of the quality of the buildings are one of the keystones of the success of the objectives fixed by the law.

Design offices will be particularly in demand by manufacturers who will have to make significant savings and who will call on specialized skills in complex industrial processes.

The coupling of electricity production installations (wind turbines, photovoltaic, small hydro) to the electricity distribution networks is complex and, in general, the techniques are little known to electricians. On the other hand, the maintenance of generators (wind turbines, hydraulic, etc.) will require new quantitative and qualitative know-how.

In the mechanical sector (engine development), power electrical engineering, electronics, needs will increase.

economic and solar thermal technical analysis

In a few years, demand will grow by a factor of 10

The age curve among employees in technical education adding an additional difficulty to the challenge ...


Read another post from Mr Reynier about energy storage

Reader's reactions


Good analysis, but from our point of view, marred by a contradiction, moreover partial, because the article is more general than that. We believe that this contradiction does not necessarily correspond to the author's opinions, but that the author has formulated it with the aim, conscious or not, of not upsetting anyone. It is a long road that never ends until getting clear ideas on any topic and then speaking it out. We ask the author not to take what follows negatively.

We therefore propose to raise this contradiction and thus add a stone to the debate.

The contradiction: if it is true (and the author put it very appropriately in italics) that the explosion of (useless ones which make the) standards on the material and allocate the subsidies on the basis of the said standards, weighs on the development of all applications in the field of solar thermal, it then becomes contradictory to call for an industrial innovation that will go even further in the direction of this standardization by offering "black box" products that will be all the more out of the reach of the basic craftsman and will have to be even more… subject to standards.

There is in this history of high-techism and standardization a hidden objective of monopolization of the market which aims to transform the basic installers into equivalent of salesmen of TVs. But then simply, as the poet says, a phenomenon of “acquired speed” or “single thought” in the sense that one thinks of technical development in this way, namely “technical development” = “product development”.

Such a "development" will ultimately benefit the same large industrial structures which for the moment install oil-fired boilers that the basic craftsman is precisely incapable for many already of understanding, and for 99%, of manufacturing. However, if we want to interest the basic craftsman, we must offer him something over which he has power and concrete knowledge, and which makes his activity in his field more “robust” in the face of the globalized market. Namely, for example against the dumpings that there will be with products made by slaves in China precisely to kill the decentralized market of grassroots independents.

If the diagnosis is this then, we must not offer new products which, even if they are better, will not do more than existing products which are already doing well, without anyone wanting them.

You have to provide technical knowledge as such. This technical knowledge must be based on an “open” product in the sense of free technology, such as Linux is open. It must result in solar thermal installations of the "mechanic" type (this is where we are resolutely against the prevailing opinions on the matter), so that the basic craftsman can intervene on them at each individual. stages of their installation, modify them in order to solve particular installation problems (which always arise in renovation, or the renovation concerns 99% of the fleet built) or sizing, dismantle them to repair / modify them, reassemble them etc. what the high-tech and compact “kits” or “black box” products on the market do not allow.

In addition, a "mechanic installation", much of its "value" of which lies in the construction / assembly work itself, can hardly be stolen because it cannot be taken out of a room. This therefore makes such solar thermal installations "socially safer", unlike photovoltaic installations or "high tech" installations (for example vacuum kits), subject to continual theft in France (the panels / sensors are sold on the market. German gray market). Such a technique also makes the task easier and saves the health and the wallet of the installer, in the sense that “mechanic” elements are lighter / less bulky, and therefore easy to move / transport / install for small businesses. equipped with basic tools (the van and the equipment and tools in it). This makes them very interesting for these small structures (in other words, having a 3m2 sensor of a cheaper room is useless if you have to pay a crane to mount it on the roof, not to mention that if it has a problem or that you have to make a modification, you have to change it entirely, ie bring it back down and put up another one…). We could enumerate other generic advantages and simple common sense which thus vaporize all the famous specialized advantages of industrial products conceived according to an “above-ground” logic.

But to come back to the basic installer, it is because he has the freedom to modify and adapt his product that he is led to take an interest in the methods of his installation, and that through this he improves its competence in this area. This makes him a craftsman, either a profession, and not a salesman, or an occupation of the working poor with ejection seat. Because a TV salesman, even if he sells a lot of TVs, is, with a cosmic exception, unable to say how a TV works and how to fix it. It can therefore be replaced overnight by another (Polish?) TV salesman that we can pay even less since the basic skill required is in any case close to zero. It is the famous fair for imbecile professions that our civilization promotes in place of the universal minimum of existence that the progress of science makes not only possible, but necessary under penalty of generalized civil war in the short term. The downside of this fact, a difficulty that we have to deal with in Switzerland a little and in France a lot, is that no one can bombard themselves overnight as a “solar thermal installer” (and especially not after having followed a phony training course). qualisol). Only continuous coaching and activity in the field allow the production of real competence. So it requires a patience that many, out of inclination, despair, ignorance, pride or stupidity, do not have.

Of course, care must be taken to ensure that the local modifications and adaptations of the technique are valid, so that the installations operate to satisfaction and therefore the customers are happy (which is vital, no offense to the sellers outside -sol, with the reputation of a craftsman who remains integrated in his environment, unlike the seller who disappears in nature once the product is sold). Otherwise we would fall into the mess of the 70s and all the bad reputation of solar that it has generated. But standard kits, including apparently inexpensive and / or standard ones, installed - one could say "vomited" - anyhow on any roof for any use - including when one could do better with the same money, for example by insulating - this is also mess.

What is needed at this stage, therefore, is not an industrialist who makes yet another miracle superproduct on which we will have put a label like we put crosses in ISO forms, but people who return the service to basic installers to judge the validity, technically and in terms of overall energy efficiency on the building, of their applications of a generic technique. And there we join the author. Such a structure can contain engineers, but also… basic craftsmen who have the bottle in the technique considered and thus coach newcomers, or even self-builders, provided that they also have bottles. Craftsmen must take the difficult psychic step of fighting against the temptation to secure their market by refusing any help from potential competitors, a mentality straight out of neoliberalism which also contributes to the fact that solar thermal, like so many other things, cannot not develop. And to help them in this task, there is the pressure exerted by the rise in competence of the self-builders, because the technique is precisely free.

This is what we are trying to do within Sebasol, an association which poses as a condition if ne qua non to be part of it, to have produced with its own hands at least one solar thermal installation that operates according to a proven technique supplied in first place. Such an association sees self-builders and basic installers working together, with a continuous flow of technical information from one to another. The withholding of information is prohibited and the craftsmen and self-builders of the network are the basis for the training of trainees with the aim of making them installers. So people who would be according to a current narrow logic, not to say degenerate, their own "competitors". The downside of course is that the training course is long, and that such “competitors” will then have acquired a realistic culture resulting from experience in the field. Their installations will be beautiful, functional, and will therefore contribute to the good reputation of solar thermal in general and of the entire network in particular. Not to mention that working together, if sometimes we emulate each other, more often than not we give each other a hand ...

Note: with this modest notice we believe we have contributed to the debate and hope it will be useful to the author. We give him permission to send this notice to whomever he wishes, obviously subject to compliance with the text. We are very busy and will not have time to fuel a controversy. We wish solar thermal good luck in France, where moreover we are doing our best within the limits of our overload rate, to keep things moving.

sunny greetings

Pascal Cretton
Sebasol Vaud / Solar Support

More information

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