Complexity of the law act as a universal barrier. Therefore, the following is needed:

• the regulation should be simple and clear, since therefore:

1. it would be easier to be applied (meaning also low costs for managing the STO)

2. it would be easier to convince stakeholders

• to have clear and straight-forward timing and deadlines (starting date for the implementation, deadlines for complying and reporting, dates for checks, etc.)

2.1.2 Development: which buildings?

In order to have a high impact, the scope of the STO should include a remarkable share of the building stock. Therefore:

• include not only residential buildings, but also tertiary activities which consume hot water (elderly homes, hospitals, jails, sport centres and gyms, etc.)

• include as many refurbishment activities as possible, for instance, foresee the obligation for any refurbishment which concerns heat supply plants

2.1.3 Development: not too many exemptions

Exemptions to the accomplishment of the law should be not too many and not ambiguous:

• in particular, clear rules should be established for historical and protected buildings/areas; it would be advisable not to have a 100% exemption, but rules for architecturally integrating technologies in order to lower their visual impact

• do not ask that the solar collectors should not be seen from street level

• do not ask for internal boiler only

• industrial buildings could be exempted

• buildings with small consumption of hot water could be exempted

• seasonal buildings (when the consumption is mainly in cold seasons!) could be exempted

2.1.4 Development: which technologies?

Several technologies could be considered when implementing a renewable heat ordinance, which is not “solar only”. The recommendations are:

• allow different technologies for complying with the obligation

• set priorities, according to technical and economical feasibility

• include only “actually renewable” heat technologies: no fossil CHP, no heat pumps

• do not “mix” heat and electricity, e. g. do not exempt from the renewable heat obligation buildings which have photovoltaic on the roof

2.1.5 Development: quantitative obligation and calculation method

For setting the quantitative obligation, the following remarks should be taken into account:

• set a quantitative obligation for covering by renewables a minimum share of the hot water or total heat consumption of the building

• do not mix obligations on heat and electricity

• the quantitative obligation chosen should be reasonably reachable, e. g. in terms of available roof area or in terms of demand fraction to be covered

2.1.6 Development: quality requirements

Quality is a key issue in a STO, since:

• mandatory solar thermal could mean lower quality solar thermal

• some Countries already experienced relevant mistrusts towards solar thermal in the recent past (e. g. Italy, Portugal)

• on the other hand…ask for the same quality requirements as for other domestic appliances and not much stricter ones!

Do not include too many technical requirements, since:

• it is not possible to check all of them

• it does not necessarily assure quality

• it prevents technological innovation and development from being applied Quality rules should be:

• clear

• applicable (e. g. if product certification is required, a reasonable amount of certified products should already be available on the market; if it is not the case, allow a time delay for complying with the certification requirements included in the STO)

• comprehensive (include requirements on design and planning, products, installation, operation and maintenance)

• for products: referring to European standards is advisable (e. g. Solar Keymark)

• for installation: you could ask for one or more requirements (e. g. certified installers, maintenance contract, etc.)

• for operation and maintenance: you could ask for one or more requirements (e. g. Guaranteed Solar Results scheme, system monitoring, random checks, maintenance contract, etc.)

• A calculation method should be provided, with the following approach:

• set a simple and clear method

• use, as much as possible, figures which Municipalities are used to (e. g. link the mandatory m2 of solar collectors to m2 of living area or to the number of building occupants)

• develop calculation sheets and provide both designers/building companies and personnel of the Municipalities with them, also training them for a correct use of the tools

2.1.7 Implementation: checks and fees

A good STO should include both checks and fees.

Recommendations for implementing checks:

• the complete approach includes 3 checks: design phase, after installation, during operation

• checks in the design phase:

1. checks work well if calculation methods are simple and the personnel in charge of the checks is properly trained

2. include specific STO checks in the ordinary building check, so no surplus costs for the work of checking should be borne

• checks after installation: the check could consist either of a in-situ inspection or a verification of the certification of the installer

• check during operation: the most effective solution is to foresee random checks and then “advertise” widely when someone not complying with the law is caught and therefore has to pay the corresponding fee

Recommendations for setting fees:

• they are needed to make people understand that this law shall be taken seriously:

• they should be high enough to “scare” building developers

• they should be higher than the additional cost coming from complying with the STO (e. g. the cost of including a solar thermal plant in the building)

2.1.8 Implementation: flanking measures

In general:

• flanking measures should be considered as part of the STO, since, without them, even the “perfect STO” could be ineffective

• they should be planned, worked out and implemented before and during the STO

• need for targeted actions, addressing the main actors involved A list of suggested flanking measures is:

• training for Municipality personnel (more than just a flanking measure, it plays a crucial role!)

• training for installers

• specific training on large scale solar thermal plants for designers

• giving the good example: develop pilot plants in your own public buildings

• information workshops for “external” actors, e. g. building companies, banks, etc.

• comprehensive web site where designers, building companies, installers can find reference documents, guidelines, etc.; a good reference is the “gestor integral” web platform developed by Barcelona Municipality

• information campaign addressing final users

• careful and targeted communication actions (see section “Birth: let everybody know why”)

2.2 Performance indicators

Following difficulties have been faced in carrying out this task:

• since STO is a relatively new mechanism, several of the analysed ordinances are quite recent and therefore no or only a few quantifiable results are available;

• most of the analysed STOs do not foresee a monitoring of their effects, which is a really negative issue, because it is not possible to compare results with the targets set in the preparation phase; this is the reason why the inclusion of a clear monitoring plan has been reported, in the previous section, as a key success factor.

2.2.1 Is it working well?

Buildings:

• number of buildings addressed by the STO (also in terms of m2 of living area and of people addressed by the STO)

• share of buildings addressed on the total building stock

• if the ordinance is not “solar only”: share of buildings (new/refurbished) which chose solar thermal to comply with the law

• real figures for surplus cost in new/refurbished buildings (check that this value is reasonable)

• how many buildings applied successfully for being exempted?

• number of cases where the minimum obligation foreseen has been definitely overcome (e. g. buildings which chose a 50% share of solar thermal on hot water demand, when the STO requirement is 30%)

Checks:

• how many people in the Administration have been trained to perform checks?

• share of negative checks in the design phase

• number of random checks in the installation or operation phase and share of negative situations

• number of sanctioned situations and rate of accomplishment (payment of the fees)

Others:

• how many “external actors” (e. g. building companies, banks, etc.) have been involved in information workshops?

• how many people have been involved in information campaigns addressing final users?

• how many Municipalities replicated a similar ordinance?

• are final users happy with the law? A questionnaire could be developed and spread

2.2.2 Impact on the development of the solar thermal sector

• installed solar thermal plants thanks to the STO (m2, kWth)

• m2 of solar thermal installed in public buildings

• growth of the local and/or national ST market thanks to the implementation of the STO (compare the new growth rate with the rates before the STO was operating)

• number of new companies manufacturing solar collectors and/or plants in your Administration/Country

• number of new certificates issued for solar collectors in the local/national market

• number of people trained on solar thermal (designer, installers, etc.)

• effects on non-obliged segments of the solar thermal market, for instance buildings not included in the scope of the STO (e. g. industrial)

2.2.3 Impacts on the local energy supply

• heat produced by the installed solar thermal systems, quantified through the energy savings (final or primary) and/or the share on the total heat demand or the hot water consumption; the figures could be measured (when metering systems are installed in the plants) or estimated from the m2 installed

• CO2 emissions avoided (calculated from the above parameters)

2.2.4 Impacts of existing stos: some examples

• real figures for surplus cost in new/refurbished buildings:

1. Spain: 0.45-0.59% increase per m2 built

2. Catalunya: 0,32-0,41% per m2 built

3. Barcelona: 0.29-0.38% per m2 built

4. Pamplona: 0.53-0.68% per m2 built

5. Baden-Wuttenberg: 20 to 34 € per m2 living area (<1% of the building cost)

• installed solar thermal plants thanks to the STO:

1. Spain: 4,900,000 m2 installed by 2010 (estimated)

2. Barcelona: from 1999 to 2007, the total installed solar thermal surface goes from 1,350 m2 to 51,436 m2 (real)

3. Ireland: 22,165 m2 of solar thermal will be installed in the Counties involved (estimated)

• number of people trained on solar thermal (designer, installers, etc.):

1. Portugal: 1,000 certified installers and dozens of already planned courses

• heat produced by the installed solar thermal systems:

1. Ireland: primary energy saving of about 270,000 MWh/year (estimated)

2. Spain: 1,536,500 kWh/year (estimated)

3. Catalunya: 84,000 kWh/year (estimated)

4. Barcelona: 32,076 MWh/year (summary 2002-2006, estimated) [1]

2. Barcelona: 5.640 t/year (summary 2002-2006, estimated)

3 Next steps

In order to support the Local Authorities involved in the project and any other European Authority interested in introducing a STO, the ProSTO project is now developing useful tools covering the whole STO process:

• STO best practice database as internet tool, basically showing the examples collected in the first part of the project. Specific characteristics of each individual best practice STOs are presented such as the motivation of local politicians, the experiences made, how the market developed, which flanking measures where implemented, which was the legal base and the administrative procedures of this individual STO, which technical criteria were required for installations etc.

• Production of model documents for STOs:

• The local law document containing the obligation to install solar thermal systems itself

• A document specifying the quality requirements on the products or the quality criteria requirements on the installation.

• A document with calculation procedures

• A document with procedures for quality control

• Elaboration of catalogue with recommendations and references for flanking measures

• STO development blueprint. This is a document with a step-by-step process description on how to develop and implement a STO on local level. The blueprint will be a practical working document guiding through the STO process, making reference to experiences made in the project, available tools, best practice examples and lessons learnt.

4 Conclusions

The market impact of well implemented STOs has shown to be high (up to a factor of ten in one year). In the best case, this action will lead to the implementation of efficient STOs in many European regions or even countries. This can lead to an accelerated growth of the solar thermal market with installation rates estimated up to 20 GWth each year (~0,5 % of Europe’s total heat demand for the residential sector).

Solar thermal ordinances are a powerful tool for promoting solar thermal and other RES in the residential sector. The European Commission is going to introduce a directive which will introduce the mandatory use of minimum shares of RES.

On the other side, STOs need a quite complex process to be introduced, since they affect a large variety of actors and stakeholders.

The ProSTO project is therefore crucial for creating show cases and useful tools for communities undergoing such a process.

References

[1] Longo and Rogall, SWW, April 2004

[2] ESTIF, Best practice regulations for solar thermal, August 2007

1.1. Characteristics of the target populations of the transference

Two different locations were selected to develop the transference actions: the village of Antofagasta de la Sierra and the settlement Los Bajos in Valle Viejo.

Antofagasta de la Sierra: the county is situated between 3200 and 4400 m above sea level in the western part of the province. The limit to the north and east is the province of Salta, and Chile to the west, Fig 1. This county is the largest, but with the lowest population density in the province of Catamarca — covering 28,000 km2 it has only 1,282 inhabitants, 70% of them concentrated in the capital of the county.

The weather is cold and dry, with a minimum temperature below 0°C, a daily thermal amplitude above 30°C, and rains below 200 mm a year.

The village of Antofagasta, the county capital, is 582 km far from San Fernando del Valle de Catamarca; however, it is difficult to reach due to the rough geographical features of the region, so that it takes approximately 9 hours by car to get to the village. The population strongly maintains their rituals and traditions; men are mostly shepherds and women spin and knit wool. The main buildings are a municipal lodging house, a private inn, a chapel, a primary school, a secondary school, and private houses all built with adobe bricks.

“Los Bajos” settlement, Valle Viejo county: this county is situated in the central valley of Catamarca at 520 m above sea level, and it covers 540 km2. It is considered the fourth county among those with the largest population and is 9 km away from the capital of the province. The settlement “Los Bajos” is next to Del Valle river bank.

This social space shares structural poverty characteristics and deficit in the possibilities to have access to goods, services and social rights.

To optimize comprehension among seniors at Escola Tecnica-Grao Duque Henry, the solar still project was taught in five separate disciplines: Computing, Construction Principles, Drafting, Portuguese, and Practical Labs. These lessons were conducted by the project coordinators and Cape Verdean instructors. Computing classes featured instruction in AutoCAD, Word, and Excel, programs relevant to still design and project proposal drafting. Solar technology research, relevant simple physics and

construction processes were taught in the Constructions Principles course. In the Drafting class students brainstormed new still designs. The Portuguese teachers assigned several essays on the solar still to integrate language acquisition and still design. Math skills and the construction process were reinforced in the practical labs. Future projects might feature collaboration with the Physics department.

The need of training in a specific domain is strongly depended on the participants’ willingness to do it. As expected, the teachers are willing to improve their knowledge focusing on renewable energy; they have not been involved in training sessions in the field and here the differences among countries were not significant.

c. Information sources accessed by the teachers

The main information sources are from scientific literature and Internet — based, this fact being the same in all countries involved in the questionnaire.

In the context of a training session, a special attention should be paid to the development of information resources, that should gather information adapted to teachers’ needs.

f Appreciation of the interest related to specific study chapters

The subjects proposed by the questionnaire designers were well appreciated by the respondents and they were proposed as part of in-service training course curriculum, as it will be further presented in the paper.

The output of solar thermal systems is in general not measured but calculated by using the installed capacity. Only for very large systems the output is measured. The assessment of the installed capacity is in general done by a questionnaire to the industry about the collector area that is sold. In a similar way also the area of non-covered collectors is assessed. This method gives a reasonable accuracy. The main differences occur in the life-time that is assumed for the solar systems. Some countries have a methodology to assess the life time and so calculate to total collector area in use.

If this is not done by the countries themselves, it should be done before international comparisons are made. The IEA Solar Heating and Cooling programme assumes a life-time of 25 years [9]. There is little knowledge about the actual systems still in use, but in a fast growing market the errors of misjudging the life-time is very small. There is a need for a better estimation of the life­time of solar thermal systems. This will be country specific, because the types of solar systems and their quality vary widely.

Surveys of the installed collector area are given for the international market by:

• The IEA Solar heating and cooling programme: an overview of the world based on the best data that the experts from the programme can find. The report includes a division between different collector types and a calculation of the produced heat.

• Eurostat: the official statistics

• The IEA statistics office: They have the same data as Eurostat

• Estif: The Estif data focus on market development. Estif includes expected market development

• EurObserv’ER: They follow the official statistics but publish the available data quicker than Eurostat. The aim is to follow the targets set by the EU.

In general the figures have an acceptable accuracy. The data is not as good as for example the electricity produced by wind power, but more accurate than the energy produced by wood stoves in households.

2.4 Methodology and Aims

The methodology is essentially an integration of information gleaned by means of questionnaire, interview and occupant diaries, together with observation and measurement:

Questionnaire: This established routines in the home, including those relating to heating, ventilation and utility activities (e. g. washing and drying clothes). It also included attitudinal responses to availability of sunlight, private outdoor space and disturbance from neighbours (mainly noise transmission). Finally it included a perceived stress scale, a positive and negative affectivity scale and a series of questions to establish personal well-being.

Interview: Face to face recorded interviews with occupants both facilitated completion of questionnaires and allowed elaboration of detail and attitudes.

Diaries: A number of occupants opted into keeping detailed diaries, recording for example habits relating to opening of windows, setting of thermostats and utility activities.

Observation: This included digital photographs, ambient weather at time of inspections, perceptions as to air quality, occupants’ habits and any relevant ‘quality of life’ factors.

Measurement: These may be categorized as a) measurement from scaled drawings; b) spot measurement of temperature, relative humidity (inside and outside) and carbon dioxide (CO2); c) ditto durational measurements (not in all case studies); and d) ambient meteorological data.

Axiomatically, there are a large number of variables, some of which are induced by occupants and some by the authors of the buildings at the time of building and since. Nevertheless, the aim is twofold: firstly to ascertain if there is an apparent association between sunlight/energy — efficiency attributes and perceived stress, positive and negative affectivity, and health/wellbeing; secondly to do the same in relation to other physical environmental indicators such as temperature (comfort) CO2 and humidity (air quality and risk of mould or dust mite propagation). In the second instance, one has to regard the solar and energy — efficiency attributes as integral; while, in the first instance, it is accepted that many other factors may function as stressors, as well as influencing health and well-being. However, the positive and negative affectivity questions are based on emotions, and as such should connect more with the senses as perceptual systems [6]. It also clearly distinguishes between positive and negative emotions, whereas the perceived stress questions are all intrinsically concerned with negativity; and questions about ailments in the well-being set relate to independent issues such as age. Thus, it is more reasonable to expect tangible associations between availability of sunlight and affectivity than it is with the other two scales.

Together with establishment of Masters’ courses at each of the three African universities, organization of sensitization Workshops is one of the major activities in the PREA project.

All six Workshops have meanwhile been conducted in the three African countries, namely South Africa, Tanzania and Uganda. They were conducted in October 2006 and October 2007, in each session with short intervals in between. All workshops had a common title, “Sustainable and Energy efficient Building in Africa” but were further differently subtitled to reflect areas of local focus which are slightly different from country to country among the three participating African countries.

2006 Workshops

The Workshop in South Africa took place at the Midrand near Johannesburg on 3-4 October 2006. Its subtitle was “DMEs Energy Efficiency and Renewable Energy Targets: Addressing South Africa’s Energy Crisis through Built Environment Interventions”, where DME stands for Department of Minerals and Energy. The particular local situation in South Africa addressed at this Workshop was the fact that the country did not produce enough electricity to meet the growing demand, giving rise to what is locally termed as an “energy crisis”. That is why this phrase was used in the Workshop subtitle. The workshop which was supported by the Development Bank of South Africa (DBSA) was attended by 150 participants.

The Workshop in Tanzania, subtitled “Addressing Tanzania’s Energy Crisis through Design and

Settlement Development” was organized at the Landmark Hotel in Dar es Salaam on 10-11 October 2006. It was attended by 32 official participants from various government offices and professional organizations and individual professionals. In addition 10 students also attended the Workshop where 16 papers were presented 6 of which were from project partners and 10 from other attendees.

In Uganda, the workshop was subtitled “Promoting Sustainable & Energy Efficient Urban &

Building Design practices in Uganda”. It was organized on 13-14 October 2006 at the Hotel

Africana in Kampala and was attended by 35 participants who included government officials mostly policy and decision makers, professionals including Engineers and Architects, university academic staff members and some students. Eleven papers were presented; of which six came from project partners and five were presented by government officials and professionals. The Ugandan Ministry of Energy and Uganda society of Architects were also represented and their papers were presented.

2007 Workshops

In South Africa the workshop was subtitled: “Socio-Economic Priorities in Renewable & Sustainable Energy Initiatives in the Built Environment in South Africa”. It was organized on 10 — 13 October, 2007 at the Sustainability Institute, Lynedoch, Stellenbosch. There were 55 participants.

In Tanzania the workshop was subtitled: “Potentials for Renewable Energy in Buildings in Tanzania“. It was organized on 15 — 16 October, 2007 at Blue Pearl Hotel, Ubungo Plaza, Dar es Salaam. There were 42 participants.

In Uganda the workshop was subtitled: “Sustainable Built Environments”. It was organized on 22 — 23 October, 2007 at Grand Imperial Hotel, Kampala. There were 72 participants.

The critical situation of electricity supply and the need for new and sustainable energy resources has been underlined by the long almost daily power cuts, especially in Tanzania and Uganda in the last few years. Coincidentally, as if to underline the fact for the Workshoppers, long duration power failures occurred during the course of the events in both Tanzania and Uganda. Water shortages in Dar es Salaam were also indicative of this power problem.

As a form of side activities, some exhibitions served at these workshops made by manufacturers of sustainable energy and building products as well as service providers in the sustainable buildings industry, such as sales representatives and installers of renewable energy products, e. g. PV modules, Solar water heaters etc. One of the other highlights of the Workshops is that they served to bring together all parties involved and interested in renewable energy activities such as businesses and respective departments and individuals in local academic institutions. Certificates were issued to Workshop participants. These certificates had some extra value because in some cases such as Uganda and South Africa they could be used to gain some professional development points which is a requirement of some professional bodies from their members in those countries.

The final proceedings with the presentations, speaker CVs and papers, as well as photos from each event were compiled onto CDs for distribution to the participants of the workshops. Also the final proceedings from 2006 and 2007 are available from the PREA website (http://prea. ises. org) by clicking on the respective workshop, i. e. 2006 or 2007 and then “Final Proceedings”.

Each of the European partner universities contributed to the workshops as expert speakers (with the exception of ULR, France). The European partners were engaged in the development of the programmes during the project meetings and contributed by sharing their knowledge as speakers during the events on their relevant topics of expertise.

Evaluation reports of the workshops were carried out and lists of participants from all six workshops are available. Many of the lessons learnt during 2006 were put into development of the programme and structure of the 2007 workshops. For instance break-away sessions were organised on specific issues as well as more time allotted to discussions — the most important means of participant involvement in the workshops.

Overall the workshops both in 2006 and 2007 were very successful. Participants in all three countries represented a diverse group, from professionals and decision makers to consultants and students.

Generally the participants were enthusiastic and eager to leam about and share their own thoughts and experiences on sustainability in the built environment and renewable energy. Discussions were engaging and brought to light many local issues about housing and energy situations in each country. The second set of workshops also saw the return of many participants from 2006.

Some barriers for the development and diffusion of the technology have been identified, such as:

• systems’ costs, which are extremely high compared to standard cooling appliances

• few experiences and realised applications

• lack of monitoring data and follow up activities

However, regardless of the relatively small number of SAC systems already installed, a trend toward the increase of the SAC market has been registered.

1. Scarce availability of information and knowledge

Difficulties have been encountered in the collection of market data and information in the partner countries (both from a technical and economical point of view; they are also due to the different quality and definitions of relevant information). Nevertheless, precious information was collected which allows a better planning and strategy for the project development.

Moreover, lack of knowledge has been registered among technicians, investors and market actors. At the same time also a strong interest among these target groups has been recognised. This underlines the importance of developing tailored training materials and courses as well as the continuous exchange with stakeholders and within the project consortium.

2. Public interest

There is an increasing interest on SAC technology also in the general public. Reasons can be identified inter alia in the climate change (which has become perceptible also in Northern European countries), in new building regulations including EE and RES minimum requirements, in rising prices for oil and electricity and in environmental awareness.

This is also attested by the interest and several contacts through the project website.

As consequence the awareness campaign is of special importance.

References

[1] Hans-Martin Henning (Ed.), Solar Assisted Air-Conditioning in Buildings — A Handbook for Planners, Springer Wien/New York; ISBN 3-211-00647-8

[2] Promoting Solar-Air Conditioning. Supported by the European Commission. www. raee. org/climatisationsolaire

[3] Hans-Martin Henning, Solar Assisted Air-Conditioning of Buildings — An Overview, Journal of Applied Thermal Engineering, 27 (2007), 1734-1749.

[4] Task 38, Solar Air-Conditioning and Refrigeration, located in the Heating & Cooling (SHC) Programme of the International Energy Agency IEA. www. iea-shc-task38.org .

[5] Edo Wiemken (Ed.) (2008), Best Practice Catalogue on Successful Running Solar Air-Conditioning Appliances, http://www. solair-proiect. eu/uploads/media/Best Practice Catalogue EN. pdf (05.08.2008)

[6] Edo Wiemken (Ed.) (2008a), Survey of Available Technical Solutions and Successful Running Systems. Cross-Country Analysis, http://www. solair-proiect. eu/uploads/media/Survey cross country. pdf

(05.08.2008)

[7] R. Battisti et al. (2008), Market Report for Small and Medium-Sized Solar Air-Conditioning Appliances. Analysis of Market Potential, http://www. solair-proiect. eu/uploads/media/Market analysis EN. pdf

(05.08.2008)

A polyfunction community center equipped with the modern technologies described in the technology transfer section was established in the village. Site for the center was determined by the community leaders involving women, and the NGO CARITAS. It is envisaged that as the center evolves the community will use the facilities more and more for education, especially information technology, improved health services, education and training, adult education classes, especially women literacy education, career development and job preparation services for young women, local access to business opportunities and telecommunications, support for micro-credit programs, civic/cultural education, radio and television news reception, and democracy and public information. It is also anticipated that as funds become available, the Center will be equipped with a special radio receiver, required to capture satellite signals from WorldSpace Foundation, (WSF).

1.1.1. Battery Charging Facility

Affordable stand-alone battery-only system design for residential lighting and other small load are made available to the inhabitants of the rural community. Those who can acquire these relatively inexpensive small systems for their homes, as well as owners of solar powered rechargeable lanterns, have the opportunity for recharging their batteries and lanterns at a charging station provided from the village power.

The background to this work is the assumption that solar electricity will play an important role in the future electricity system. If solar electricity will stand for a large part of the electricity production, the situation may arise instantaneous that the access of solar electricity exceed the demand, and if the produced electricity not can be stored or exported, this electricity will be seen as an overproduction which can not be used.

The goal with this study is the following:

• Calculate how much solar electricity that can be installed in Sweden without overproduction of solar electricity. The basis is use of Swedish climatic data and today’s electricity consumption.

• Calculation of how large the overproduction are if the more solar electricity is produced, that is if we allow the solar electricity production instantaneous exceed the electricity consumption.

• In the calculations solar radiation data from several sites are used for studying how the solar electricity production may vary in different sites. This can answer the question if low production in some parts of the country (for example due to overcast weather) is compensated by more clear weather in other parts of the country.

• Calculation of the optimal direction of PV modules in Sweden if large areas are installed. This can answer the question if it is possible to direct the modules to other directions than south to maximize the electricity production without causing overproduction of electricity.

• The calculations will be performed with several years of climatic data to see the difference between the years.

One limitation with the study is that the calculations are performed only for Swedish circumstances and with Swedish data, although the Swedish electricity grid today is a part of a larger North European electricity system. One reason is that this was a limited study, and calculations with data for a larger region should demand a lot of expensive data. However, it can be assumed that when overproductions will arise in Sweden, which is during daytime in summer, the situation often will be similar in neighbour countries, which limits the possibility for export of excess electricity produced by PV technology.

Furthermore, two simplifications are used in the calculations.

• It is assumed that it is possible to distribute the produced solar electricity in the electricity grid without restrictions

• It is assumed that all electricity produced by PV installations up to the point when the production equals the consumption can be consumed. This means that it is assumed that all other electricity production in Sweden can be shut down when this occur.

The last simplification is questionable, since there in reality always are electricity productions which can not be turned of without loosing production, and this is further discussed in chapter 4. However, the main goal with this study is to find the approximate size on how much PV that can be installed, and for this the approximations are acceptable.

1. Method

The climatic data used are hourly mean values for ambient temperature, direct and diffuse radiation for five Swedish sites (see table 1), spread over the country. We assume that the distribution of PV installations in the future will be according to the population distribution, and therefore the different climatic data are weighted according to how large parts of the Swedish population that live near the different sites. Climatic data for the full years 1988-1991 was used.

To get data for the electricity use, we use hourly data from [1] for 1996-2005. The optimal should have been to use data for the same years as we had climatic data, but when we study the profile of the electricity usage between different years, the difference is small. If we compare a certain period for several years (for example the first week in a certain month), the large difference is not between years, but between weekdays (Monday-Friday) and weekends (Saturday-Sunday). A typical profile for the electricity usage was therefore created from the data, and it was assumed that this profile was representative for the years of climatic data that where studied (1988-1991).

ш

5

0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 1. Average electricity use in Sweden during 1996-2005. During the weekends, the

electricity use decrease. Data from [1].

In the calculations, the simplification is done that the PV modules have 10% system efficiency, independent on module temperature and irradiation level. By comparing the calculated produced electricity with the assumed used electricity the same hour, it is possible to calculate how large PV area that correspond to the need during critical hors (daytime, summer). It is also possible to calculate what happens if another distribution of modules over Sweden is assumed (other to what corresponds to the population distribution), what happens if the PV modules is directed to other directions than south, and what happens if the PV area in Sweden is larger than the area needed to precisely avoid overproduction.

2.

Result

Figure 3 shows the electricity production from grid-connected solar electricity during four years when the solar cell area has been chosen so the electricity production during sunny summer days exactly matches the electricity demand (marked with stars in the figure). This area corresponds to 128 Mm2 PV area (referred to as A0 in this text). It is assumed that this area is divided between the sites according to the population distribution and that the modules have optimal tilts and azimuths according to table 1. If we assume that the modules are equal distributed over the five sites, the maximum possible electricity from the sun before overproduction starts is the same (approx. 9,5% of the total electricity consumption in the country), which is shown in table 2. Furthermore it is seen that the maximum possible solar cell area before overproduction starts is 5-10% larger if the PV modules are divided between the sites, compared to concentrating all the PV production at a single site. This effect is due to a more uniform production since local extreme weather conditions are dampened with country wide PV production.
/

25

О о

0_

о ш

Figure 4 shows how large part of the Swedish electricity production that can be covered if the solar cell area is larger than A If the total solar cell area is 2 * A almost 18% of the electricity need (blue line) can be covered by solar electricity while the overproduction is slightly less than 6%. If the PV area is 3 * A 23% of the electricity need can be covered, while the overproduction is

amply 18%, etc. Figure 5, which can be of academically interest, shows how a large part of the electricity production that can be covered in the total PV area is substantially larger than A0. The

maximum amount of the Swedish electricity use that can be covered direct by PV (without storage), is by natural reasons 50% since the PV cells don’t give any output during night-time, but then over 90% of the possible generated solar electricity can not be used due to overproduction.

100

90

80

70

60

50

40

30

20

10

0

In [2] results are also presented on how sensitive it is to direct the PV modules direct to south. For ’’small” PV areas, below A the output will be only 75% if the modules are directed to east and

west, compared to if they are directed to south. When the total PV area starts to exceed 2 * A the

direction of the PV modules get less important, but still the largest output is if the modules are directed to the south. The calculations also show that if the total PV area is equal to or larger than 4

• A it is favourable to direct the PV modules (with equal areas) to south-east and south-west instead of south since this generates a more even electricity production over the day.