Category Archives: EuroSun2008-9

Power Purchase Agreements for Solar Thermal. Break Down Barriers to Renewable Energy. Implementation in North America

I. Sinclair

Vice President — Engineering, Mondial Energy Inc., 2240 Queen St. E., Toronto, ON M4E 1G2, Canada
* Corresponding Author, isinclair@mondial-energy. com


Mondial Energy Inc. has pioneered the sale of solar thermal energy through Power Purchase Agreements to the building industry in North America. Requirements to meter remotely energy delivered in real time has bought key advancements in metering and monitoring. This has brought the industry to commercial scale for the first time in Canada. The need to ensure consistent energy delivery and to satisfy investors has resulted in significant improvements in ongoing commissioning and maintenance practices. The data acquired has led to identifying solar thermal as a fuel switching alternative to electrical generation at peak times in Ontario. Keywords: Solar thermal, power purchase agreements, fuel switching, North America

1. Introduction

Until very recently the solar thermal industry in Canada has been struggling to climb out of its position as a niche, cottage industry, primarily serving the residential and small commercial/institutional markets only. This is mostly due to historically low energy prices for both electricity and natural gas in comparison with other World markets. However other important barriers have been owners’ perceptions of risk associated with solar thermal in a primarily cold climate, maintenance concerns and also lack of access to capital.

The introduction of the Power Purchase Agreement model through Mondial Energy Inc. — where the owner contracts with Mondial to pay for, own, install and operate the system, has removed these barriers, while bringing economies of scale to the solar thermal industry. As a result the largest solar thermal hot water systems in Ontario have all been built under this model in the past two years.

This business model is now being adopted by local governments as a way for them to bring renewable energy to their buildings without having to manage the work and associated risk, or provide up-front capital.

A Net Zero Energy House for Southern European Climates: Feasibility Study

A. Augusto1*, G. Carrilho da Gra^a1,2, M. Lerer2
1FCUL, DEGGE, Campo Grande C8, 1749-016 Lisbon, Portugal, 2Natural Works, Lisbon
Corresponding Author, afa@natural-works. com


A Net Zero Energy Building (NZEB) is a building that, on annual basis, draws from outside sources an amount of energy that is equal to, or less than, the energy it produces on site from renewable energy sources. Building energy efficiency is a priority in the EU: buildings represent 40% of the total final energy demand. This study aims to size a renewable energy system based on solar thermal (ST) and photovoltaic (PV) systems that meets all energy needs of an optimized single family house for the Mediterranean climate, combining reduced energy needs with efficient building energy systems. The house yearly heating, cooling, and domestic hot water needs are 14.9 kWh/m2, 1.8 kWh/m2 and 33.3 kWh/m2 respectively. After sizing a set of ST and the PV systems, an analysis was performed to identify the best system configuration from a financial and environmental perspective. The cost and performance of the NZEB system shows low sensitivity to the size of the ST, whenever solar hot water is used to its maximum, with the best cases occurring in a wide range of panel areas: 4-8m2. The introduction in the analysis of the renewable Portuguese micro-generation financial incentives scheme shows great potential for financially attractive NZEB homes.

1. Introduction

Energy use in buildings represents about 40% of the European Union final energy demand [1],as a result building energy efficiency has become a top priority [2]. From a building sustainability perspective the goal is to conceive an efficient building that, on annual basis, draws from outside sources an amount of energy that is equal to, or less than, the energy it produces on site from renewable energy sources. In order to avoid on site electrical energy storage the Net Zero Energy Building (NZEB) approach is gaining support: when a building has a surplus in its electricity production, the surplus is injected into the grid, conversely when its production is not enough to satisfy the demand, the building draws from the grid.

With current technology, the off-grid approach seems difficult to implement [3], both from an economical and technical viewpoint, due to the seasonal mismatch between energy demand and renewable energy supply. In the off-grid case, the excess of renewable energy produced in the building is wasted and cannot be used to balance energy needs during periods of building’s higher energy demand.

For the on-grid NZEB concept to succeed, the building should:

• Be energy efficient / have reduced energy needs (natural lighting and ventilation, passive heating and cooling)

• Have efficient building energy systems (including domestic appliances)

• Have renewable energy systems — solar thermal, PV, etc.

• Be served by a flexible energy infrastructure — the on-site energy production system should be adapted to the local renewable energy potential and to the building’s needs; the distribution system (grid) should be able to supply and receive energy to and from the building.

This study aims to identify the most efficient NZEB configuration for an optimized single family house in the Mediterranean climate (Lisbon). Renewable electrical production will be done using PV since it is the most promising technology for urban and suburban areas. For domestic hot water and, in some cases, space heating, solar thermal panels will be used (the system with faster payback for this application).

Tasks done on solar cooling

Among the topics covered by the partners along the project, can be found: Biomass, thermal and photovoltaic solar energy, wind power, geothermal resources management etc. In CARTIF we have been mainly working on the biomass and solar cooling, topics. For this communication, we are going to focus on solar cooling, describing exclusively those actions done for the diffusion of solar cooling applications.

Cooling with solar energy is an especially attractive idea if we take into account: that the cooling loads coincide with the maximum irradiance; that these utilities can use the residual thermal energy of other processes, thus increasing efficiency; and that, by combining solar heating and cooling at different times of year, the use factor and performance of the utilities can be improved.

1.4. Specialization Training Course

The objective of the course was training on the concepts necessary to design and setting up thermal water heating installations in general and solar water cooling installations more specifically. It was given information about different typologies of facilities, as well as about the various components of a thermal solar system.

The target people in this course were design and installation engineers, technicians and professionals that were interested in this kind of technologies and in particular those who wanted to know something else about applications of solar cooling.

The course was very useful for the participants. Some of them have asked for more information about this technology and are still in contact with us for any other activity related to solar cooling that we should prepare.

The course was divided in two parts, one of them more general related to solar thermal systems, and a second one more specific centred in solar cooling.

De schedule of the course was:

Topic 1: Design and calculation of installations.

This topic was used as introduction for the course, showing different configurations usually adopted for thermal solar installations: Sanitary Water Heat (SWH), Radiant floor and swimming pool, and different combinations of those two. For the dimension process, three different methodologies were shown: usability method, based on the concept of critical radiation, f — chart method, for the dimension of swimming pools and finally, for radiant floor, the Degree-Day method. It was also explained the calculation of pumps, pipes and expansion vessels. At the end of this topic the students should have the skill to calculate installations as well as to apply the usability method to calculate solar cooling installations.

Topic 2: Heat Transfer applied to thermal solar energy.

The solar energy applications are based on the transformation of the solar radiation onto heat, and its posterior transmission to a fluid. Taking this into account, it was considered necessary to describe the basic mechanisms of heat exchange, to understand how the principal elements work: solar collectors and heat exchangers.

Topic 3: Fundaments on cooling.

Solar cooling consists of the production of cold using hot. In this lesson was made an introduction technological and historical of the cold production, being valid too as introduction to the solar chillers operation. There were shown resemblances and differences with respect to the conventional systems. Finally, was explained the psychometric diagram and the calculation of the impulsion temperature for an air thermal conditioner.

Topic 4: Elements of solar installations.

On this topic were described some characteristics of the solar thermal installations. Among other things were described the different kind of collectors, the tanks, heat exchangers, pumps, pipes, insulation, and other elements used on the installations.

Topic 5: Solar cooling concepts.

On this journey were briefly shown different ways to produce solar cold as well as the parameters used to characterize the installations and the most typical configurations.

Topic 6: Adsorption chillers.

We began whit the description of the adsorption process, to show next the more habitual adsorbent substances. Finally are described the adsorption chillers, either with discontinuous cycle, or with recuperation or with phase change.

Topic 7: Absorption chillers.

In this lesson were described the different absorption technologies and the more frequent couples of substances. It was shown too how the working conditions affect to the performance or the power, in order to interpret their interaction with the solar installations.

Topic 8: Desiccant cooling systems.

On this topic, are commented the advantages of the desiccant systems, as well as the elements that form them, either solids or liquids. They are described the different configurations and how they behave against changes on the temperature of the regenerator.

Topic 9: Dimensioning of solar cooling installations.

On this last topic, were described different programs available for the calculation of solar cooling installations: SACE [2], TRNSYS [3] and SolAc [4].

The course lessons were celebrated in a lecture room rented on the Engineers University (ETSII) of Valladolid — Spain (5th-9th of May). There were 17 attendants and the total length was 20 hours.

Other Requirements for Success

Training local entrepreneurs and technicians is necessary to ensure that the system designs are appropriate to local conditions, and to ensure that traditional values and customs are built in to the business culture. Also important is the training of development workers and decision makers to help overcome the barriers to successful and widespread use of renewable energy to meet the basic needs of rural people. The training programs under this project have not effectively address these issues. Because of their significance to the overall success of an energy for sustainable development program, below is a brief comment on these training activities.

Taleghan test Facility site

Taleghan test facility site is a solar test facility site which was planned to be the first solar systems reference in Iran. This test facility site is not completed yet but some of the planned projects were completed and the others are started and the construction is in progress. There are different facilities in this site which include: Fresnel system, Dish Stirling, Solar Power Tower and Parabolic Trough collector. All these systems will be implemented as pilot projects. The Fresnel system and Parabolic Trough Collector with 5m aperture have been implemented.

Some other extra solar facilities for domestic applications were designed and implemented in this site, they are: Solar Dryer, Solar Desalination and Solar Cooker. There is a 30 kW photovoltaic power plant in this site also. The photovoltaic power plant is a grid connected system which injects about 36 GWh into grid annually [4].

Подпись: Fig. 4. Prototype Central Receiver Power Plant Plan[4]

A pilot solar power tower was designed for this site and will be implemented in near future. Figure 4 shows the plan of this solar power tower.

Base line assessment

The first activities carried out within the ProSTO project are related to the analysis of following existing STO cases:

• Region of Baden Wuerttemberg — Germany

• County laws — Ireland

• National law — Portugal

• Codigo tecnico, Decret d’Ecoeficiencia, Ordenanza Solar Termica de Barcelona, Ordenanza de Pamplona — Spain

• Regolamento edilizio Carugate, decreto regione Lazio, decreto Comune di Roma, decreto 311/06 — Italy

The data available through these questionnaires have been used to update the existing document “Best practice regulations for solar thermal”, published by ESTIF in August 2007 [2]. The updated document will be available on the project website, as well.

A European workshop has been organised for the project partners: European experts who have been involved in existing STO implementation presented their experience, the strong point and the weak points of each STO.

The most innovative outcome of the project so far is the analysis of success factors and performance indicators, which will be described in the next paragraph. The success factors and performance indicators are quite clear and almost unanimous, meaning that a good STO could be developed following these guidelines.

2.1 Success factors

Educational activity at schools

100-year of Sergey Korolev, 150-year of Edward Tsiolkovsky and 50-year of the first artificial Earth-satellite jubilees have stimulated us to start a new educational experimental project “Space technologies, ecology and clean energy in schools of the future” for Moscow schools in 2007. The essence of the project is to create an experimental educational platform on the basis of а number of Moscow secondary schools. We are involving schoolchildren in activity associated with high technology of real time monitoring of the Earth surface and solar energy conversion.

Portable, inexpensive receivers (described in section 2.1) were installed in ten Moscow Schools designed to get and process space images of the Earth sending by satellites in real time mode. School students started getting the experience of work with the Earth surface images taken from the space under supervision of their teachers, and later on independently (Fig. 13). They are taught to bind these Earth surface images to the geographic map using specially designed algorithms. Within the project, schoolchildren also acquire basic knowledge related to renewable energy using experimental solar PV modules installed on the roof of school building (Fig. 14).


Pupils monitor, in real time, solar radiation by measuring electricity generated by the solar module and compare these data with information received from satellites according to scheme at Fig.13. A new design (without EVA) of 10 W solar modules with organic-silicon polymers encapsulant (VIESH) was used for school project [2] (Fig.13). The size 500 х 500 mm2 is very suitable for experiments in schools.

Team training and field research

Each work group was composed by 01 professor and 04 Engineering and/or Physics students. The training course had included solar geometry concepts, solar collectors and storage tanks, small, medium and large systems functioning characteristics, attending to variable factors found at each location. With practice classes, students had learned how to use the field research Kit, composed by GPS, tape measure, compassing, turn indicator and digital cameras used to register the visited systems.

All data observed were registered by filling technical and behavioral questionnaires, and by producing two sketches: architectonic and hydraulic. These sketches included verification of collectors orientation, tilt angles, array scheme and distance, main characteristics and identification — also verified for storage tanks -, accessibility and safety conditions, obstacles around solar collectors and auxiliary system’ characteristics. Figure 4 illustrates the field research.


Figure 4 — Field research

4. Obtained results

The concluded part of this project, in which three cities were studied, had summed a number of 274 visited systems, containing 4105 solar collectors. About 8777m2 of collector area were observed for a total hot water storage volume of 492m3. Also, this research had evaluated systems of different functioning period that were divided into 4 groups. This evaluation can be observed at Figure 5 for Belo Horizonte and Campinas cities.

Подпись: Visited installations' age
Подпись: 40 -| 36 36 > 15 years 10 < years < 15 5 < years < 10 < 5 years Unidentified

Belo Horizonte □ Campinas

Figure 5 — Visited installations’ visited

This comparative evaluation is not performed for Rio de Janeiro because there were no low — income households solar systems installed more than 5 years ago; therefore these data were not included in this analysis.

System sizing

The characteristic consumption of the studied buildings was estimated relating the total solar collector areas and volumes for each location. Campinas, where medium and high income households with 1 or 2 storey buildings were visited, presented an average collector area of 8m2/household, storage volume of 600 liters/household and an average hot water consumption of 150 liters/person. The average storage volume found at Belo Horizonte’s systems is 7500 liters/building, 240 liters/household and nearly 60 liters/person. This last number is considered low if compared to high-income households consumption observed at Campinas. This fact was linked to the consumption compensation between the apartments and the small available area to install solar systems that can cause reductions over the f-chart value and increase the auxiliary system consumption. Moreover, there’s a tiny use of hot water in kitchens, which can also raise significantly the systems sizing prediction. At Rio de Janeiro, the average consumption for low — income households studied is 58 liters/person.

Products Quality

The solar collectors inspection had displayed the presence of oxidation, infiltration, painting and insulator deterioration and broken or damaged glasses. At 10 to 15 storey buildings’ systems visited, 12% presented infiltration, 10% painting deterioration and 5% oxidation, showing these three problems as the most common ones. Thus, the infiltration problem can be considered as the most critical, since, in most of the cases, it is the main actor that causes other problems, such as painting deterioration and oxidation.

It is reasonable to associate those problems with low incidence of systems maintenance, proved by the great number of dirty solar collectors: nearly 30% at large and 67% at small systems for medium and high-income households.

Large systems storage tanks presented good functioning, although oxidation problems were detected at the structural base: low (22%), medium (13%) and high (9%). Again, this problem can be a lack of periodic maintenance consequence.

The observed results about equipments approved by INMETRO market, point to an interest growth demonstrated by specialized stores. At Rio de Janeiro nearly 45% commercialize only these products, while at Belo Horizonte this value raises up to 70%. For these stores, 80% of products have the PROCEL Stamp, which is considered the best quality product, classified as “A”.

Auxiliary Heating Systems

Basically, LPG gas predominates at large systems in Belo Horizonte, where 74% of them use this kind of auxiliary heating. Meanwhile, at Campinas, where small residential systems were analyzed, the electric auxiliary heating is the most used, reaching 66% of studied households. At low-income households visited at Rio de Janeiro, which integrated a special program of the electric energy company, all the auxiliary systems are electric, represented by the resistance installed into the storage tank or the electric shower.

Safety, accessibility, monitoring and system’s maintenance

Another problem noticed is the bad conditions of systems accessibility (Figure 6). In large systems, 30% presented elevated and risky access, whereas in small systems this number corresponds to 46%. The lack of monitoring and maintenance might be associated to accessibility difficulties, since this problem obstructs the necessary equipment maintenance.


Figure 6. Solar heating systems accessibility examples

It was detected a general absence of monitoring systems and consumption control of hot water and gas or electric energy. In 90% of small systems, and 71% of large ones this occurrence were presented.

5. Conclusions

Preliminary data results observed in this research demonstrate the need of creation of a Solar Water Heating Systems evaluation program, through quality indicators definition. This strategy would evaluate essential aspects for proper functioning of the solar system, which include: hydraulic array, products quality, auxiliary systems, collectors’ orientation and tilt angles, shading occurrence, accessibility, safety, monitoring and system’s maintenance. At the same time, a Good Practices Manual for Solar Water Heating in Brazil should be developed, with the creation of formal training programs focused on design, installation, operation and maintenance of solar systems. This new program, along with the equipment certification, already established in Brazil, will help the Brazilian solar heating market to grow with sustainability and will contribute for its current national’s scene changing.


[1] PROGRAMA NACIONAL DE CONSERVACAO DE ENERGIA ELETRICA. “Avaliagao do Mercado de Eficiencia Energetica no Brasil: Pesquisa de Posse de Equipamentos e Habitos de Uso da Classe Residencial no Ano Base 2005”.

[2] LEITE, H. G. Consideragoes sobre amostragem. Departamento de Engenharia Florestal, Universidade Federal de Vigosa. 2004.

[3] MINGOTI, S. A.; Analise de Dados Atraves de Metodos de Estatistica Multivariada — Uma Abordagem Aplicada. Editora UFMG, Belo Horizonte, 2005.

[4] DUFFIE, J. A., BECKMAN W. A., Solar Engineering of Thermal Processes, John Wiley & Sons,

INC, 2a Edigao, 1991.

[5] INSTITUTO NACIONAL DE METEOROLOGIA — INMET — pelo site www. inmet. gov. br acessado em junho de 2007.


Cidades, Belo Horizonte — MG, pelo site www. ibge. gov. br Accessed on: Jun. 2007.


The SEE EU Tool project

The project, gathering an educational multi-actor partnership: universities (as newest research and

development dissemination actors, responsible with the training course development — course development, implementation and evaluation), high schools (as teachers’ working real environment — teachers and their students as beneficiaries of the training program), teacher training institutions (as experienced institutions with adults’ training focused on educational activity, involved in the project for specific course delivery and teaching materials development), educational authorities (the actor responsible with the legislation related to organisation, implementation and evaluation of the educational process for the realisation of educational aims at pre-university level, involved in the project in the design and implementation of the training tool), and specialized institution in the content of the renewable energy systems implementation (knowledge-providers). The partnership involves education providers and beneficiaries from eight countries:

• Universities: Transilvania University of Brasov — the coordinator; University of Applied Sciences, Aachen, Germany; Hogeschool Gent, Belgium; Delft University of Technology, the Netherlands;

• High Schools: Marie Curie Highschool, Dzialoszyn, Poland; College for Natural Sciences, Brasov, Romania;

• Teacher training institutions: ASPETE, Patras, Greece; Associazione Kelidon, Milano, Italy; Teachers’ Centre, Brasov, Romania;

• School authorities: District School Inspectorate, Brasov, Romania; Izmir Province National Education Directorate, Turkey;

• Specialized institution: Romanian Agency for Energy Conservation.

The aim of the project is to develop a complex training tool in the field of sustainable energy,

consisting of:

• Teacher training materials: hard copy manual; a user friendly eLearning package — CD supported — for (self)training on experiments containing a laboratory guide, and a practical training kit. The training manual is aimed to ensure the continuation of the project after its end-date, further providing the information;

• A course for in-service training of the high school teachers, in the field of sustainable energy: training methodology, integrating face-to-face training activities with ICT — based ones. This course is aimed to test parts of the training tool in the partnership, with high school — teachers groups.

Also the testing of the training tool parts in the real class environment was envisaged. A specific part of the project is dedicated to evaluating, internally and externally, the project’s activities and outcomes. The teachers’ in-service training course concept is schematically presented in Figure 1. The activities during project life time are distinguished here: the evaluation of the training needs, the in-service training course curriculum design and testing (in-service training course). As a result of the in-service modules, teacher-students have to propose the implementation of the renewable energy systems subjects implementation in the real classroom environment.

• A core of trainers by selecting the human resources for the project, to improve and update the existing infrastructure in the partner institutions for the optimum development of the project and to disseminate the project outcomes through the partners and attendees of the course.

1st International Congress on Heating, Cooling, and Buildings, * 7th to

The Evaluation of Needs


Curriculum design


Curriculum testing implementation



Curriculum implementation


Classroom implementation

Figure 1. The concept of course design in the SEE EU Tool project

The European targets for renewable energy

In a proposed directive on the promotion of the use of energy from renewable sources from the European Union [1], an ambitious target of 20% contribution form renewable energy is set. The current contribution of solar thermal towards the total renewable energy supply is only 32 PJ (2006 figures). This is less than 1% of the total final energy use of renewable energy and only 0.1% of the 25.000 PJ final heat demand in the EU-27 [2]. This is still far from the potential that has been assessed by the European Solar Thermal Technology Platform (ESTTP) of 50% of the total heat demand [3,4].

For reaching the 20% target, a large growth in the use of renewable energy from the current 6% production of renewables is essential. Solar thermal can contribute to this growth, but it is essential that solar thermal heat production is included the national and European energy statistics in a proper way.