Amasonen: A Design Proposal for a Mixed-Use Building with Integrated Solar Cells

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Amasonen

A Design Proposal for a Mixed-Use Building with Integrated Solar Cells

Ellinor Gros

Architectural Engineering, master's level 2018

Luleå University of Technology

Department of Civil, Environmental and Natural Resources Engineering

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AMASONEN

A Design Proposal for a Mixed-Use

Building with Integrated Solar Cells

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I

Title: AMASONEN

– A Design Proposal for a Mixed-Use Building with Integrated Solar Cells

Author: Ellinor Gros, ellgro-3@student.ltu.se Publication: Master Thesis, 30 Hp

Program: Civilingenjör Arkitektur – Husbyggnad, 300 Hp University: Luleå University of Technology

Examiner: Adolfo Sotoca, Professor and Subject Representative at Luleå University of Technology

Supervisor: Berta Morata, Doctoral Student at Luleå University of Technology External Supervisor: Susanne Appelberg, Office Manager and Architect, SAR/MSA, at

Tengbom Linköping

When no other sources are mentioned, images and illustrations are made by the author.

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II

PREFACE

This master thesis comprises 30 Hp and represents the finishing project for the program Civilingenjör Arkitektur, a five-year master’s program in architectural engineering, at Luleå University of Technology. The thesis was conducted in the spring of 2018.

I would like to thank my supervisor Berta Morata for the advice and guidance she has given throughout the project. I would also like to thank my supervisors at Tengbom in Linköping, specifically Susanne Apperlberg, for giving me this project and providing me with the information needed to carry it out, as well as giving me input and advice along the way.

Lastly, I would like to thank all the people who have supported me during this period.

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III

SAMMANFATTNING

Med den växande energikonsumtionen i världen idag, den minskande mängden fossila bränslen och deras negativa påverkan på miljö, är utvecklandet och ett mer utbrett användande av förnybar energi ytterst viktigt. En av de lovande miljövänliga energiresurserna är solenergi. Teknologin för att producera elektricitet från solenergi med hjälp av solceller utvecklas kontinuerligt och växer ständigt på marknaden.

Syftet med detta examensarbete är att illustrera hur solceller kan integreras i en byggnads design, och hur detta kan skapa mervärde för byggnaden. Avsikten är även att ge en indikation på ifall en integrerad solcellsinstallation är profitabel, samt vad som skulle krävas för att få fler byggnadsutvecklare att investera i solenergi.

En studie om solceller utfördes för att erhålla kunskap om de olika sorters solceller och solcellssystem som finns samt deras möjliga integration i en byggnad. Studien inkluderade även en undersökning om varför solcellsinstallationer inte är särskilt vanligt förekommande idag. Fallstudier på projekt med integrerade solceller har även utförts. Detta gjordes för att få en förståelse för hur solpaneler kan användas som designelement. Studien utfördes som en systematisk litteraturstudie genom en kvalitativ metod.

Stads- och platsanalyser genomfördes som ett första steg i gestaltningsprocessen. Analyserna fokuserade på rörelse, grönområden, klimat, funktioner och den arkitektoniska karaktären for staden och platsen.

Studierna gjordes for att bilda en uppfattning om miljön byggnaden skulle placeras i, samt dess förutsättningar. Dessa analyser följdes av volym- och solstudier för att komma fram till en byggnadsdesign som skulle uppfylla beställarens önskemål, medan samtidigt skapa bra ytor för placering av solcellerna.

Examensarbetet resulterade i ett gestaltningsförslag för två multifunktionella byggnader med integrerade solceller. De resulterande byggnaderna är placerade i utkanten av Linköpings innerstad. Byggnaderna är designade för att interagera med de omkringliggande byggnaderna och den resterande staden, samtidigt som de bidrar med något nytt och spännande. Byggnadernas placering och höjd bestämdes genom en kombination av solens rörelse över tomten, för att skapa bra ytor för solpanelerna, samt fastighetens förutsättningar. De integrerade solpanelerna är placerade på tak och fasad. Möjligheten för semitransparanta solceller i fönster och glasräcken undersöks även. Solpanelerna på taken består av solcellstegelplattor och är placerade på den östra sidan av den norra byggnadens tak samt den västra sidan av den södra byggnadens tak. Dessa plattor har även matchande tegelplattor utan solceller inuti, på andra sidorna av taken, vilket innebär att ingen skillnad syns mellan de två sidorna. Fasadpanelerna är placerade så de täcker hela de utstickande trapphusen på byggnaderna. Panelerna är också placerade på de resterande delar av de väggar riktade mot sydväst och sydöst. Här är panelerna, däremot, placerade i ett mönster som matt de rinner ner för väggarna. Panelerna är placerade för att undvika skugga, eftersom skuggning minska solcellernas effekt. Solcellerna är jämna, svarta tunnfilmssolceller och panelerna har matchande glasskivor som är placerade där designen krävde paneler, men placeringen inte var bra ur ett solstrålningsperspektiv.

Resultaten av de grova beräkningarna på projektets solcellsinstallations lönsamhet visar att investeringen skulle ha en återbetalningstid på cirka 15 år. Detta värde inkluderar då det förväntade investeringsstödet från staten på 1,2 miljoner kronor, samt den reducerade kostnaden av de byggnadsmaterial som solpanelerna ersätter. Solpanelerna i gestaltningsförslaget är inte av standardstorlek. Hade de varit det hade

kostnaden för investeringen gått ner, och enligt de grova beräkningarna skulle återbetalningstiden då minska till runt 10 år. Den producerade elen utgör omkring 60 procent av verksamhetselen för byggnaderna. Om semitransparanta solceller inkluderas går värdet upp till runt 80 procent. Trots att den producerade elen inte täcker byggnadens totala elförbrukning minskar den mängden köpt el, som troligtvis inte kommer från en förnybar energikälla. Slutsatsen är därmed att en integrerad solcellsinstallation är ekonomiskt lönsam. Solpanelerna bidrar både till byggnadens estetiska värde och byggnadsfunktioner, samt med elektricitet från en förnybar energikälla. Att investera i en solcellsinstallation sätter också ett bra exempel vilket leder till att fler vågar chansa på solenergi.

Att få mer byggföretag att investera i solceller kan göras genom att öka den nu bristande kunskapen om solenergi och solceller, processen av att designa och installera ett solcellssystem, samt lagarna angående solenergi och solcellsinvesteringar. Ytterligare ett hinder för solenergin är de höga kostnaderna för installationerna. Priserna för solceller sjunker dock kontinuerligt, tack vare utvecklandet av tekniken sant tillverkningsprocessen, samt det växande antalet tillverkare. För att öka hastigheten av denna process borde alltså fler investera i solceller då en förhöjd efterfråga leder till fler tillverkare, vilket i sin tur leder till minskade priser. Staten kan också hjälpa till genom att erbjuda forskningsstöd samt till exempel skattesubventioner för att göra solenergi mer åtråvärd.

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IV

ABSTRACT

With the growing energy consumption in the world today, the decreasing amount of fossil fuels and their negative impact on the environment, developments and greater use of renewable energy resources is crucial. One of the promising environmentally friendly energy resources is solar power. The technology for producing electricity from the use of solar cells is continuously developing and is growing on the market.

The objective of this master thesis is to illustrate how solar panels can be integrated into a building’s design, and what value this gives to the building. The purpose is also to give an indication of whether an integrated solar panel installation is profitable, and what is required for more building developers to invest in solar power.

A study on solar cells was conducted to gain knowledge of the different types of solar cells and systems and their possible integration into buildings. The study also included research on why solar cell installations are not more common today. Case Studies were also conducted on projects with integrated solar cells. This was done to gain an understanding of how solar panels can be used as design elements.

The study was done as a systematic literature study through a qualitative method.

City and site analyses were carried out as a first step in the design process. The analyses focused on the movements, green spaces, climates, functions and architectural character of the city and site. The analyses were done to attain an impression of the environment the building would be placed in, and its requisites.

These analyses were followed by volume and solar studies to come up with a building design that would fulfill the requirements of the client, while creating good areas for placement of the solar panels.

The master thesis resulted in a design proposal for a mixed-use building with integrated solar cells. The resulting two buildings are located in the outskirts of the city center of Linköping. The buildings are designed to interact with the surrounding buildings and the remaining city, while at the same time bringing something new and exciting to the mix. The buildings’ placement and height were decided by the combination of the movement of the sun over the plot, so as to create good areas for the solar panels, and the requisites of the site. The integrated solar panels are placed on the roofs and facades of the buildings.

The possibilities of semitransparent solar cells in windows and glass railings is also examined. The solar panels on the roof consist of solar roof tiles and are placed on the east side of the north building’s roof and the west side of the south building’s roof. These tiles have matching roof tiles without solar cells inside, on the other side of the roofs, meaning that no difference can be seen between the two sides. The façade panels are placed to cover the entire protruding stairwells of the buildings. Panels are also placed on remaining parts of the south-east and south-west facing facades but are here placed in a pattern as though they are trickling down the walls. The panels are placed to avoid shade as shading of the panels reduces their effect. The solar cells are smooth, black, thin-film solar cells and the panels have matching glass panes that are placed were the design opted for panels, but the placement was not good out of a solar irradiation perspective.

The results of the rough calculations on the project’s solar panel installation’s profitability shows that the investment would have a payback time of approximately 15 years. This, when counting in a government support of 1.2 million kroners and the reduced cost for the building cover material that the solar panels

replace. The solar panels in the design proposal are not in standard sizes. Would they have been so the investment cost would have been lower and the payback time, according to the rough calculations, would be around 10 years. The produced electricity constitutes around 60 percent of the operational electricity for the buildings. If semitransparent solar cells are included the value goes up to 80 percent. Although the produced electricity does not cover the complete electricity needs of the buildings, it still reduces the amount of bought electricity. Electricity that would most likely not come from a renewable source. The conclusion is, therefore, that an integrated solar cell installation is economically profitable. The solar panels contribute both the aesthetics of the building and building functions, as well as electricity from a renewable source. Investing in a solar cell installation also sets a good example and will lead to more investors taking a chance on solar power.

Getting more building developers to invest in solar cells systems can be done by increasing the, today lacking, knowledge of solar energy and solar cells, the process for designing and installing a solar cell system, as well as the laws regarding solar power and solar power investments. Another obstacle for solar power is the high costs of the installations. The prices on solar cells are, however, continuously dropping, because of the development in technology and the manufacturing process, as well as the growing number of manufacturers. To increase the speed of this process more building developers should invest in solar cells, as a higher demand will lead to more manufacturers, which will then lead to reduced prices. The government can also help by offering research support and for example tax subventions to make an investment in solar power seem more worthwhile.

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V

INTRODUCTION

The introduction chapter describes the background, purpose, disposition, method, focus and delimitations of the project. The research question of the master thesis is also presented here.

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Background

In today’s society, critical issues are impossible to overcome without energy. The energy consumption in the world is continuously growing. The main source of energy in developed countries today comes from fossil fuels, of which the resources are limited, and their effects are a threat to the environment. Energy supply is therefore one of the most pressing matters of today. (Kosyachenko, 2011)

Due to the extreme use of fossil fuels in the world the amount of carbon dioxide in the atmosphere is rising, leading to climate changes across the globe. The greenhouse effect, together with acid rain and petrochemical smog are well known factors of the unreasonably high use of energy created from fossil fuels. (Green, Andersson, Hedström, & Boström, 2002) These factors are thus strong motives to developing new technologies and finding alternative, environmentally friendly, energy sources. Renewable resources with good potential are wind, water and solar energy. (Liljegren & Marklund, 2009)

With minimal ecological impact and low maintenance costs, solar power is, thus, a promising substitute for fossil fuels. (Kreindler & Tudorache, 2010) The sun emits great amounts of energy every day, all that needs to be done is to take advantage of it. This can be done by the use of solar cells and collectors that convert the solar energy into electricity or heat, respectively. (Green et al., 2002)

The conversion of solar energy into electricity by the use of solar cells is one of the most up-and-coming, yet challenging, energetic technologies. The conversion principle, photovoltaic conversion, is improving rapidly and, thus, becoming more and more popular on the global market. (Kreindler & Tudorache, 2010) The solar cell technology is suitable for urban environments and the conversion efficiency of a solar power installation only depends on its size to a very small extent. Thanks to this, even small installations can be worthwhile, meaning that they can be attractive to even the individual homeowner. The development of solar cells allowing them to be integrated into buildings has opened up great opportunities. Because of this, solar cells can replace traditional building materials for the building envelope, resulting in lower costs of the investment. The development in the appearance of solar cells will most likely also help strengthen their place on the market. (Hemmerle, Weller, Jakubetz, & Unnewehr, 2010)

Purpose

The purpose of this project is to enunciate how to integrate solar cells into the design of a building. This includes investigations of why the use of solar cells on buildings is not very common in Sweden today, and how to change that. A possible part of the reasons for this is believed to be the fact that solar cells have not been very aesthetically appealing. As a result of continuous studies, and the development of new types of solar cells, this fact has changed. There are now numerous formations of solar cells, and ways of which to integrate them into buildings. It is, however, likely that many still hold on to the belief of the negative aesthetic appearance of solar cells. For this to change, more good examples of successful solar power projects, with integrated solar cells, are needed.

The goal with this project is therefore to, with the knowledge gained from the research, create and present a design proposal of a mixed-use building complex with integrated solar cells.

Research Question

The objective of this master thesis is to answer the following research question:

o How can solar cells be integrated into the design of a building, and in what way would this give a surplus value to the building?

With the follow-up questions being:

o How economically supportable is it to invest in an integrated solar cell installation?

o What is required for more building developers to choose to install solar cells on their buildings?

o How should a building be shaped to get the most use out of solar cells?

Disposition

The report is divided into six chapters; introduction, literature study, case studies, design process, design proposal and discussion and conclusion.

Introduction – The introduction chapter describes the background, purpose, disposition, method, focus and delimitations of the project. The research question of the master thesis is also presented here.

Literature Study – This chapter presents theory about solar cells and their integration in buildings aesthetics. The information given in the chapter aims to help answer the research question and aid in the design proposal with the use and integration of the solar cells.

Case Studies – For a deeper understanding of the use of solar cells and how they can be integrated in the design to increase their intake of the sun, several case studies are conducted. The buildings studied are chosen because of their unique or innovative use of solar cells and or their close emplacement to the site of the design proposal.

Design Process – This chapter presents the process conducted to reach the design proposal. Here the different pre-studies and procedures are described as well as the fusion of the literature study and design.

Design Proposal – During this chapter the final building design is described, including functions, building materials, layouts and placement of solar panels. The design proposal is presented both in writing, drawings and illustrations.

Discussion and Conclusion – This chapter answers the research questions and discusses the results of the master thesis. Further improvements of the project, both in terms of design and further research, are described.

Method

This master thesis is divided into two parts; research and design. The knowledge gained in the research is applied to the design proposal. The research is conducted through a literature study and several case studies on suitable projects involving solar power.

The method used in the research is of a qualitative nature. This method is conducted by gathering information through interviews, observations and analyses of previous studies. In comparison to a quantitative method, the qualitative method does not focus on statistical information, but rather information of an abstract nature. (Ahrne & Svensson, 2015)

Case Studies

A number of case studies are made on projects which have solar cells integrated into their design. The projects are chosen due to either their innovative use of solar cells and or their location. The studies are

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3 conducted to gain ideas and a better understanding of possible aesthetic uses of solar cells. Information about the studied projects is gathered from books, articles, and the webpages of the architects or building companies. Each project has thereafter been analyzed by the author through both text and sketches.

Literature Study

A literature study on solar cells and their integration into buildings aesthetics is conducted through the use of a systematic literature study. This is done by searching, critically reviewing and summarizing literature within a chosen subject. A systematic literature study aims to create a combination of data gathered from empirical studies, which are built on information gained from real life experiences. (Forsberg &

Wengström, 2016)

The information used in the study is gathered from books, e-books, reports and scientific articles. The search engines used for the research has been Google Scholar and the university library’s search engine.

The search work is made with terms like “solar cells”, “solar power”, “solar cell aesthetics” and

“photovoltaics”, and searches are done in both English and Swedish. The sources of found literature are analyzed and reviewed to verify the reliability of the information, before having it inserted into the research.

Design Process

The design process is built up of several different steps. The process is an iterative one, beginning with pre-studies of the site and project and leading up to the shaping of the buildings.

City Analysis

A pre-study of the city’s architectural character is conducted, to gain an understanding of the environment the building will be placed in. This is done by an analysis of the city map, together with previous knowledge of the city, to acquire knowledge of the movement in the city. Additional information is also obtained from Linköping’s architecture program for the city center.

Site Analysis

A study of the site is conducted in order to better understand the requisites of the plot. The study is conducted through a study visit during which the site’s climate, functions and its surrounding buildings is analyzed. Additional information is, among others, gained from Tengbom and detail plans of the premises.

Program

A program for the project is conducted to structure up everything that needs to be included in the building.

The program is created to fit the wishes of the client and to achieve an even consumption of electricity during the day. The program is conducted through the use of an early version of the project program for the site, received from Tengbom, which is adjusted to fit the new functions and size of the building.

Volume Study

As a first step of design a volume study is conducted. This is done by an iterative process of sketching and drawing of simple models in SketchUp.

Solar Study

Solar studies are conducted in SketchUp, parallel to the volume study, to check whether or not the volumes received a good amount of sun.

When the final model is complete, a second solar study is conducted in Revit Architecture 2017, to ensure that the rooms get the right amount of sunlight, and to establish which areas are best for the solar panels.

Modelling

Once the final volume of the buildings is complete a more detailed model is created in Revit Architecture 2017. The shaping of the building is done with focus on optimizing it for the placement of solar panels.

The knowledge gained in from the literature study is applied to the buildings shape and design. Drawings of the design proposal are then drawn from this model.

The choice of modeling software is made due to the fact that Revit is a BIM-software, and not simply CAD like many others. Revit is becoming more and more common in the construction industry, and it is therefore good to have plenty of experience in working with this software.

Focus & Delimitations

The design proposal is for a building in Sweden, and the master thesis is therefore conducted to fit the laws and circumstances that exist there.

The design proposal is done to a conceptual stage, therefore details like fire solutions, installations and water drainage system is not dealt with. This is due to the restricted time of the project. Delimitations for building structure and construction method are made so as not to have the project become too extensive.

Therefore, only an overall plan of the building structure, with materials, is made, in the scale 1:50. No further details are made.

As the focus of the thesis lies on the solar panels and their integration into the buildings aesthetics, the main focus is on the outer shell of the building, where the solar are placed. As the inside of a building of a building greatly affects the outside, floorplans for the buildings are made. Because of the limited time of the project, however, the layouts do not have a considerable amount of detail put into them.

As this project is of a conceptual nature no specific manufacturer and distributer of the solar panels is chosen. Only the type of solar panels used is decided. No exact study on how much electricity will be gained from the solar cells is conducted. Rough calculations are done so as to give an impression of the value that the solar cells give.

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LITERATURE STUDY

This chapter presents theory about solar cells and their integration in buildings aesthetics.

The information given in the chapter aims to help answer the research question and aid in the design proposal with the use and integration of the solar cells.

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5

Solar Energy in Sweden

There are several different aspects that decide how much energy can be assimilated from solar radiation by the use of solar cells and collectors. These are the location, the amount of sun hours available, the reduction in the atmosphere, the absorption and refection in clouds, and the angle of the panel in comparison the horizontal plane. Areas around the equator have an angle of incidence of about 90 degrees.

This is also where the distance through the atmosphere is the shortest. Therefore, these areas take in a larger amount of solar energy than those in the northern and southern latitudes. (Andrén, 2011)

Solar radiation can be divided up into direct and diffuse radiation. The amount that reaches the earth in a specific location is mainly affected by the local weather. Direct solar radiation is almost completely absorbed and reflected in clouds. Therefore, most of what hits the earth is diffuse, or indirect, radiation.

The sum of the solar insolation that can be collected is called global radiation, which can be identified as scattered light; direct sunlight that causes sharp shadows. The desert areas of the world get an average of 2500 kWh/m² and year, while the average amount in Sweden, for the southern regions, is 1000 kWh/m² and year, and 800 kWh/m² and year in the north. These numbers refer to a horizontal plane. In Sweden, these number are increased by around 25 percent for an absorbing object with and angle of 30-45 degrees from the horizontal plan and is directed toward the south. The numbers are also affected by the location in the country. The best conditions are on the coast, where an absorbing object directed toward the south, with an angle of 30 degrees, gets the solar energy amount of around 1250 kWh/m² and year. Worst conditions are in the northern inland regions where the same object would have an effect of 900 kWh/m² and year. (Andrén, 2011)

Many believe that Sweden is not a good place for PV-systems because of the rather low number of sun hours. However, the fact is that the efficiencies of solar cells are affected by the temperature, and actually have a lower efficiency at high temperatures. (Skoplaki & Palyvos, 2009) This entails that Sweden, having rather low temperatures, even during the summer, has good conditions for solar cells.

Types of Solar Cells

There are several different ways of converting solar energy into electricity. A wide spread technique, common in power plants, uses sunlight concentrating devices to heat up water. The resulting high- temperature steam operates an electric generator. The use of photovoltaics is another system. This system converts solar radiation directly into electricity and therefore takes away the middle man, water.

(Kosyachenko, 2011)

The conversion of solar radiation into electric power in a photovoltaic solar cell, or PV-cell, happens when a photon entering the cell excites an electron from the valence band into the conduction band, as long as the electron does not recombine either in the volume or the semiconductors surface. If this is true, the photon is absorbed and in doing so contributes to the electric current. (Brendel, 2011)

There are several types of PV-cells on the market today. These differ in both in terms of structure and material. These aspects both affect the appearance and efficiency of the solar cells. The two principal groups of solar cells are the traditional crystalline silicon solar cells, and the newer thin-film solar cells.

(Hemmerle et al., 2010) PV-cells have a lifespan of around 25-30 years depending on the type of cell and the individual product (Brandsma, Kadic, & Nilsson, 2016).

Crystalline Silicon

The typical crystalline solar cell consists of a thin plate of silicone and two metal layers. The first, patterned, layer of metal partly covers the side of the silicon plate that is exposed to sunlight. The plate

and the metal layer are in electrical contact with each other. The second layer of metal covers most of the backside of the plate. An electrical voltage occurs between the two metal layers when the sun hits the solar cell. The cell therefore acts as a battery that is charged for as long as the sun rays hit it. (Green et al., 2002) A single crystalline solar cell is about 10x10 centimeters big and has a thickness of a few millimeters.

These cells are rarely sold individually, but are often assembled in a weather protected packaging, a solar cell module. One of these modules usually contains 36 solar cells. The front of the module is made up of a panel of hardened glass that protects the solar cells behind it. (Green et al., 2002)

The manufacture of the silicon used in crystalline solar cells involves many stages. Quarzite and charcoal are put together in a high-temperature arc furnace from which metallurgical grade silicon can then be obtained. The purification of the metallurgical grade silicon is then commonly conducted by a method of fractional distillation of chlorosilanes. The semiconductor grade silicon is then produced by reducing the chlorosilanes with hydrogen at high temperatures. The semiconductor grade silicon produced can then be processed further depending on what type of solar cell it is to be used for. The two most common crystalline solar cells are the mono- and poly-crystalline solar cells. (Kosyachenko, 2011)

The thickness needed for crystalline silicon to have total absorption of solar radiation is around 1 centimeter. For the material to absorb 95 percent of the solar radiation a thickness of about 300 µm is necessary. An increased level of absorption can be achieved by reflecting light from the, metal covered, back of the solar cell. In an ideal case, the thickness will only need to be half as much. Because such a thick layer is needed for total absorption, many companies compromise and create plates with a thickness of around 150-250 µm, resulting in an absorption of about 94 percent. (Kosyachenko, 2011)

Monocrystalline Solar Cells

The monocrystalline solar cell is the type of solar cell that uses the highest level of purity of silicon, and therefore is one of the most efficient solar cells (Kosyachenko, 2011). The cells are made up of single- crystalline ingots which are obtained through purification of the semiconductor grade silicon. This is usually conducted through a process called the Czochralski technique, which is adapted from the microelectronics industry. During this process the semiconductor grade silicon, or polycrystalline silicon, is recrystallized. (Kosyachenko, 2011) A single-crystalline cylindrical rod is produced, that is slowly pulled out of the silicon melt. The rod is then cut into wafers. This is done to obtain rectangular shaped wafers. Unfortunately, during the cutting, because the kerf is about as thick as the saw, a lot of non- recyclable silicon dust is produced that therefore goes to waste. The offcuts of the cylinder, however, can be melted down and reused. (Hemmerle et al., 2010)

The complete process of purifying the silicon, producing the ingot, and finally cutting them into wafers make up around 40-55 percent of the total cost of the solar module. The monocrystalline solar cells are therefore very expensive to make. (Kosyachenko, 2011) The high efficiency of the mono-crystalline solar

Figure 1: Monocrystalline Solar Cell (Oskar Lürén, n.d.)

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6 cell cannot quite make up for the high production costs, and these cells are nowadays, therefore, being increasingly replaced by polycrystalline or thin-film solar cells (Brendel, 2011).

Polycrystalline Solar Cells

The process of creating polycrystalline solar cells skips the procedure of recrystallizing silicon. The wafers are instead cast into square ingots from liquid silicon. Under strictly controlled temperature conditions the ingots are then allowed to solidify. The result is a multitude of crystals with different orientations.

(Hemmerle et al., 2010)

Because of the simpler production process, the manufacturing costs of this type of solar cells is lower than that of the monocrystalline one (Brendel, 2011). The lower level of purification does however come at a price. Due to crystal impurities, the occurrence of random grains of crystalline silicon and a substantial concentration of dislocations the polycrystalline silicon often has defects. These defects result in a lower efficiency of the cells. The polycrystalline solar cells are thus both less expensive, but also have lower efficiency than the monocrystalline solar cells, resulting in a relatively similar cost per unit of generated power for the two. (Kosyachenko, 2011)

Thin-Film Solar Cells

The thin-film solar cell is an up and coming alternative to the crystalline solar cells, due to its lower production costs. The thin-film solar cell, as its name indicates, has a thinner layer of photoactive material than the crystalline solar cells. (Green et al., 2002) These cells are made up of one or more layers of photoactive semiconductors deposited on to a substrate (Kaya & Sahin, 2009). This substrate can for example be a glass, metal foil or plastic (Kosyachenko, 2011). The substrate helps stabilize the panel to avoid breakage, and in that allows a thinner layer of photoactive material (Brendel, 2011). The size of the produced module is, therefore, not constrained by the size of the silicone plate, but is decided by the size of the substrate, which can be many times bigger. Because the cheap substrate makes up the majority of the module, the material costs for this type of cells are significantly lower than those for crystalline solar cells. (Green et al., 2002)

Unlike the silicon wafers, the thin-film can consist of different types of semiconductors, not necessarily silicon. These direct-gap semiconductors used in thin-film solar cells can absorb solar radiation with thinner layers than the silicon wafer. These materials can obtain almost complete absorption at a thickness of only about 3-4 µm and have an absorption of 95 % at 0.4-0.5 µm. (Kosyachenko, 2011)

Amorphous Solar Cells

The first thin-film solar cell on the market used an amorphous silicon as its semiconductor. Amorphous solar cells have mostly been used in smaller sizes, for example in solar powered watches of calculators,

but are now becoming bigger and bigger. The amorphous silicon is fabricated without melting, which is done when producing silicon wafers. In this form the atoms are more randomly arranged than in a crystalline panel. (Green et al., 2002)

The production of an amorphous solar cell is done by applying a thin layer of a transparent conductor onto a substrate. A laser then carves a pattern into the conductor. The direct-gap semiconductor, amorphous silicon, is then deposited onto the conductor. A pattern is carved into this layer as well, however, this pattern is slightly shifted compared to the underlying layer’s. A layer of metal is placed on top of the semiconductor, with a similar, once again slightly shifted, layer. The shifting in the patterns allows the individual cell surfaces created by the patterns to connect. The substrate is much bigger than a single solar cell and is therefore covered in several cells. The cells automatically connect in series, thus eliminating the process of connecting individual cells to one another, as in a crystalline solar cell module. (Green et al., 2002)

Placement

The angle and rotation of a solar panel has a great impact on its electricity production. To maximize its efficiency a solar panel should be both rotated and angled toward the sun. The ultimate placement therefore depends on where in the world the panel is located. In places north of the equator, solar panels facing south are optimal while in the south of the equator northern facing modules are preferable. In Europe the maximum energy yield is, generally, achieved by a south oriented system with a slight rotation to the west, mounted at a 30-40-degree angle from the horizontal plane. However, smaller deviations from the optimal angle and rotation do not result in any major losses. (Green et al., 2018)

Vertical systems, as on facades, placed directly to the south have a seventy percent efficiency level compared to optimally angled ones. These systems work best during mornings, evenings and during most part of the winter, when the sun is low. Vertical systems facing east or west work well in the mornings and evenings and have an efficiency of 50-60 percent of the maximal. North facing vertical systems, in Europe, do not get any direct sunlight, except for short periods in the early mornings or late nights during the summer. In spite of this, thanks to diffuse radiation, these systems still get an efficiency of 20-30 percent of the maximum, (Green et al., 2018)

The optimal angles for the modules can be calculated more precisely for specific areas. From calculations made in the online software provided by the European Commission, Photovoltaic Geographical Information Systems, the optimal inclination for solar panels in Linköping, where the project is located, is 40 degrees. (European Commission, 2017)

Figure 3: Thin-Film Solar Cell (Nyedal Solenergi, 2015) Figure 2: Polycrystalline Solar Cell

(Oskar Lürén, n.d.)

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7 To ensure an optimal angle of the solar panels throughout the day, the panels can be connected to solar trackers. These track the sun and use the information to rotate and incline the modules so that they are perpendicular to the sun at all times. (Clifford & Eastwood, 2004) By following the sun, the performance of the solar panels is increased by about 40 percent compared to a static panel placed at an optimal inclination. Solar trackers are commonly used in large grid-connected PV-plants. By maximizing the solar collection, the cost of delivered electricity is reduced. (Lorenzo, Pérez, Ezpeleta, & Acedo, 2002)

Due to the large, more advanced, mounting systems for systems with solar trackers, assumptions can, be made that these systems are not ideal for integration in buildings. This assumption can also be drawn by the fact of the continuous movement of the panels, as this impairs their abilities as part of the building envelope. Because of the more advanced technology for mounting of solar cells with solar trackers these systems also have higher investment and maintenance costs than static ones (Hemmerle et al., 2010).

However, this higher cost might be compensated by reduced cost of delivered electricity.

Avoiding shade is very important when it comes to placement of solar panels, as shading can cause drastically reduced electricity production. A shade free placement is very important, especially for the summer months, as this is when the most energy conversion takes place. (Andrén, 2011)

Appearance

The appearance of solar panels varies both between the different types of solar cells as well as within a type of solar cell. The appearance of a solar installation greatly affects the aesthetics of a building and is therefore a very important matter to consider.

The crystalline solar cells have long been the most common type of solar panels and the appearance of the crystalline solar panel is therefore a common general impression of what a solar panel looks like.

Because of the polycrystalline technology, these solar cells are not uniform in color but consist of blue, overlapping triangles that vary in tone depending on light conditions. What is more, as one solar panel is made up of a number of solar cells, placed side by side with some distance between them, the backing material for the panel can be seen. This material is usually in a reflective white color as this ensures low temperatures, thereby optimizing the efficiency. To attain a more uniform appearance, however, the color of the backing material can be chosen to match the surrounding solar cells. (Hemmerle et al., 2010) As opposed to the crystalline solar cells the thin-film cells have a more homogeneous look, as seen in Figure 3, which is commonly seen as a positive aspect in terms of design. Amorphous solar cells are generally black with a red tone to them. (Green et al., 2002) The panels can nowadays, however, come in several different colors, increasing the design opportunities (Hemmerle et al., 2010). However, the color of the panel does affect the efficiency of the panel, as light absorption varies between colors. With this in mind, a black solar panel is the best choice as it will absorb the most amount of light. (Green et al., 2002)

Integration

As an installation of solar cells is fundamentally different to many other, traditional, building materials, products and construction forms, its integration into a building, can be rather complicated. This fact also complicates the buildings integration into its rural or urban environment. (Hemmerle et al., 2010) Because it is a relatively new technique, however, it does offer opportunities for architectural creativity (Green et al., 2002). When designing a new building with photovoltaics, the design freedom is great. As the solar installation and the building can be coordinated and integrated with each other, they can appear as a unified entity. The integration work when adding a solar installation to an existing building is more complicated.

This, because of the fact that there is a limit to the adjustments, both architectural and constructional, that can be made to the building and the solar cell system. (Hemmerle et al., 2010)

To achieve a clear design language, designing with photovoltaics requires a constructional integration that is directly tied to the architecture. The need for a constructional solution that supports the architectural concept is especially high in integrations on facades, where the solar installations are particularly obvious.

As a common covering material for photovoltaic solar cells is glass, the panels often resemble windows.

The modules are reflective, and therefore in great contrast to the commonly opaque surfaces of traditional facades. The shape, size and brightness of the solar panels also contributes to their resemblance of windows. One difference, however, is the depth that they bring. Windows are often set back in the façade and also offers the viewer a small insight into the building, therein giving the façade a third dimension.

The windows also act as important reference points for the users, as they link them to the outside world.

Like windows, solar cell modules divide a façade, but do so only in two dimensions as they are commonly placed as the outermost layer of the building’s envelope. The panels are most often mounted close together.

Thus, the shadows formed in the joints are insignificant, and the panels therefore don’t add any depth to the façade. (Hemmerle et al., 2010)

Roof Installations

The traditional way of mounting solar cells on top of existing roofs, on separate loadbearing supports, is called a stand-off system. However, integrating the solar panels into the roofs, where the panels are part of the building envelope, replacing the cover material, is becoming more and more common. This type of installation is called an integral system. (Hemmerle et al., 2010)

On flat roofs, a stand-off system is preferable, out of an efficiency point of view, due to the fact that an integral system has lower yields because of its low inclination. Yet the integral system does compensate with a lower weight of the installation, together with the reduced erection work. On pitched roofs, the orientation and angle of the solar panels is decided by the roof itself. The highest solar irradiation, for buildings with pitched roofs, is reached on south-facing roof surfaces. South-east- or south-west-facing roof surfaces are also sufficient, although they are not optimal. Structures penetrating and rising above the roof cover, shading the solar panels, diminish the yield of the panels. (Hemmerle et al., 2010)

As the solar installation of an integral system works as the covering system of the roof, it must provide with rainproof roof covering. This can be done either by overlapping the modules, like shingles, or by placing them in plastic housings which have special cover strips placed at the joins. Though these systems are supposed to provide sufficient water proofing, adding a layer of roofing felt or covering sheeting is often advised. This ensures that precipitation driven in between the panels by the wind, as well as condensation, can run off. (Hemmerle et al., 2010)

The integral systems used on roofs can use either standard modules or modules developed specifically as solar roofs. The use of standard modules is widespread and is also much less expensive than those with solar roof elements. However, developments of solar roofs are continuously being made and these systems are therefore becoming more and more common. The solar roof panels can be used in conjunction with practically any type of roof coverings. The modules range in size and appearance, from large-format modules, panels integrated in batten and seam constructions, to solar roof tiles. (Hemmerle et al., 2010) A well-known version of the last mentioned, that has recently been put on the market, was produced by Tesla. The Tesla Solar Roof fulfills all the functional properties of a cover material and the tiles look just like traditional roof tiles. The tiles come in four different styles; textured, smooth, tuscan and slate. Made in tempered glass, the tiles come either with or without solar panels inside, thus making it possible to

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8 integrate solar panels on parts of the roof, without any noticeable difference between the parts. (Tesla, 2018) While solar panels, because of their principal component being glass, are often considered fragile (Hemmerle et al., 2010) the Tesla Solar Roof tiles are said to be three times as strong as regular roof tiles (Tesla, 2018).

Small modules, like the solar roof tiles, require a greater amount of installation work. The advantage of these systems is, however, that complicated roof surfaces are more easily covered with solar cell. As a compromise, a development of modules that replace more than one tile has been made. This lowers the amount of wiring work while at the same time retaining the appearance and functional properties of regular roof tiles. (Hemmerle et al., 2010)

Façade Installations

Solar installations on facades can also be divided into two groups. These are called cold and warm facades, where cold facades only help, or act as, the weatherproofing system for the facades, and warm facades are fully integrated and fulfill all façade functions. (Hemmerle et al., 2010)

The constructions of solar panels onto the facades can be done in several different ways. These forms of constructions can be cladding with ventilation cavity, post-and-rail facades, double-leaf facades and prefabricated facades. South-facing cold facades with ventilation cavities are often preferred as façade installations. The solar modules fulfill the functional properties of a façade material, while the remaining wall elements used, as the structural framing and insulation, can be the same as when using a traditional façade material. (Hemmerle et al., 2010)

As mentioned, a vertically mounted solar panel is not optimal in terms of efficiency. However, this is compensated by the large area that the facades make up, that would otherwise be unexploited, in terms of solar power. (Hemmerle et al., 2010) Helping to make the investment more worthwhile is the fact that integrated façade installations also replace other façade materials bringing down the cost of the investment.

(SolTech Energy Sweden, 2018)

The solar modules can come in both standard sizes and be custom made. The custom-made modules are often more expensive than the standardized ones. To bring down the cost of the investment it is therefore

a good idea to consider the solar installation at an early stage in the design to be able to coordinate it with the building layout and design. (Hemmerle et al., 2010)

Out of a design perspective, the integration into the façade plays a big role. The panels can be chosen to cover the whole façade, or only parts of it. The panels can also be arranged to form a pattern on the building.

Decisions about whether or not to match the panels in color and appearance with the remaining facades and façade areas need to be taken. With thin-film solar panels, matching glass panels without solar panels can easily be made. This increases the design opportunities as the panels do not need to be confined to spaces with good light conditions. All these factors have a great impact on and help create the building’s architectural character.

Transparent Panels

Solar panels can be defined as transparent by two different aspects. Either the whole panel, including the solar cell, is transparent, or only the backing material. Having only the backing material be transparent is a system used for crystalline solar panels. In these partially transparent panels, the several solar cells placed in the panel are opaque, but the gaps in between the cells are transparent, allowing light to shine through.

This is for example, commonly used for canopy roofs. (Hemmerle et al., 2010)

Thin-film solar panels can have the actual solar cells be transparent. The panels can have different degrees of transparency. The transparency level affects the effect of the solar cell, which is linear to the transparency. A solar panel with 50 percent transparency thereby has a 50 percent effect of the maximum.

(SolTech Energy Sweden, 2018)

Figure 5: Cold Solar Cell Facade (SolTech Energy Sweden AB, 2018) Figure 4: Tesla Solar Roof Tiles

(Tesla, 2018)

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9 The semitransparent solar panels can replace regular glass panes in windows, curtain walls, glass roofs and glass railings. The panels both produce electricity and provide sunshade. The wires connected to the cells are concealed in the frames or profiles encapsulating the panels. The possibility of using solar panels as transparent elements opens up a lot of opportunities for building integration. (SolTech Energy Sweden, 2018)

Sunshade Installations

Sun shading systems are ideal placements for solar panels. This, because the position of an external element intended to act as protection from direct sunlight optimal for solar panels as it yields a very high efficiency.

The good ventilation beneath the panels also helps increase the amount of electricity produced. The sunshade installations can either be fully opaque, partially transparent or semitransparent. (Hemmerle et al., 2010)

The sunshade solar installations have two subdivisions; fixed and movable systems. A good and effective type of fixed sunshade system is rigid awnings. Depending on the inclinations the awnings can protect against the sun glare during selected periods of the day. The angle of an awning, on a southern façade that protects primarily from the summer sun is around the same angle as that for optimal effect of the solar cells. Awnings on eastern and western facades are not as sufficient, however, because of the less favorable angle of incident. (Hemmerle et al., 2010)

Movable systems use solar trackers to optimize the energy yields for the solar panels. These systems therefore provide better sun shading throughout the day, as well as more generated electricity. Because of the advanced solar trackers, they have higher production and maintenance costs than fixed systems. A simple form of movable system is sliding shutters. Here, the movable louvres adapt to the angle of the sun.

A good compromise between fixed and movable systems is to a combination of the two. This system combines fixed solar panels with movable shading elements without solar cells. An example of this can be

to have sliding shutters made from expanded metal, which can be pulled out from behind fixed, vertical solar panels. (Hemmerle et al., 2010)

PV Systems

Solar cell systems can be either stand-alone systems, which are independent from all utility grids, or grid- connected systems, that connect to another electricity grid (Hemmerle et al., 2010).

Stand-Alone

A stand-alone system consists of a PV-generator, energy storage, AC and DC consumers and elements for power conditioning. The PV-generator can consist of a number of arrays, which are composed of several solar modules, which, in turn, can consist of one or more solar cells. (Hansen, Sørensen, Hansen, &

Bindner, 2000)

These types of systems are completely independent, and it is therefore necessary to ensure that the electricity consumption does not exceed the electricity production. The energy storage, often consisting of battery banks, which store temporarily additional electricity. This electricity can then be used at times when there is a shortage of produced electricity, for example during the night when the sun has gone down.

(Hemmerle et al., 2010) The batteries make up a costly part of the system, especially when a highly reliable electricity supply, day and night, is required. A good charge controller is thus a good investment.

Intermittency is therefore something that inevitably must be dealt with for stand-alone systems relying on natural energy flows in the environment. (Fthenakis & Lynn, 2018) The energy banks also require high maintenance and often implicates high losses of energy (Hemmerle et al., 2010).

The load for this type of a system can be either DC (e.g. lighting and television) or AC (e.g. heaters or electric motors). The power conditioning system usually made up of a regulator, a converter and blocking diodes, renders an interface between all elements in the PV system, thereby giving protection and control.

(Hansen et al., 2000)

Stand-alone systems are often used in places without comprehensive electricity grid, for example in thinly- populated or third world countries. A stand-alone is also a good option for mobile applications like boats and motorhomes, as well as systems connected to traffic and infrastructure like parking ticket machines and mobile communication transmitters. (Hemmerle et al., 2010)

Grid-Connected

To avoid the high costs, maintenance and loss of energy of storage systems, the PV system can be connected to the electricity grid. The electricity grid can then be seen as a virtual energy storage. In this type of a system, an inverter acts as the interface between the solar installation and the grid. The inverter converts the direct current that the solar panels generate into the customary alternating current which is required in households or industry. The surplus electricity generated, if any, is fed to the grid. At times when the electricity consumption exceeds the amount of generated electricity, the additional electricity needed is drawn from the grid. (Hemmerle et al., 2010)

The grid-connected system can be divided into three concepts; plant-oriented inverter, module-oriented inverter and module-integrated inverter. Which concept to use depends on the size, geometry and arrangement of the PV-system. A plant-oriented concept uses one, central inverter for the entire PV- system, and the modules are connected either parallel and or in series on the DC side. A module-oriented inverter concept has a number of modules connected in series, on the DC side, to several inverters, as well as a parallel connection on the AC side. A module-integrated inverter has one inverter per module, a parallel AC connection, but no DC-cabling. (Meinhardt & Cramer, 2000) The inverter converts DC

Figure 6: Semitransparent Solar Cells in Curtain Wall Facade (SolTech Energy Sweden AB, 2018)

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10 electricity to AC and acts as an energy and system manager. Because of its complex technology the inverter is one of the elements in the system associated with the most waring down and breakdowns. (Hemmerle et al., 2010) The concept of module-oriented inverters, also called string converters, can be regarded as the optimal grid-connected PV systems in Europe. (Meinhardt & Cramer, 2000) The DC wiring system for this concept is rather simple and is therefore a good fit for building-mounted PV systems. As the inverters emit both heat and noise, placing them in cool, dry and dust-free places is preferable, for example in the attic or the basement. This way the noise does not cause any disturbance either. When several inverters are used, they should be placed with some distance between them, to avoid mutual heating effects. It can also be a good idea to divide them up in more than one room. (Hemmerle et al., 2010)

In Sweden today, there is compensation to be received for excess electricity that goes to the electricity grid. The law says that the network operator companies must pay a compensation to the solar plant owner for the excess electricity fed to the electricity grid. The size of the compensation depends on different factors like in which city the solar installation is located and what electricity distributer is used. (Brandsma et al., 2016)

The network operator companies can, however, charge the solar plant owner for an input subscription, which is required for feeding of own electricity to the grid, or for switching the electricity meter. Yet, this charge can, by law, not be claimed if the solar plant owner is a net consumer on a yearly basis, and the solar plant has a maximum effect of 43,5 kW. (Brandsma et al., 2016)

Why Not More Common Today?

The production of electricity through the use of solar power is, currently, the fastest growing type of renewable resource (Liljegren & Marklund, 2009). Even so, it is not nearly as common as it could be.

There are three basic technical prerequisites for solar cells to become of more general use. These are low production costs, high efficiency and reliability (Green et al., 2002). Continuous studies are being conducted on developing and improving solar cells to make them more accessible and cost worthy. Due to the lower production costs compared to monocrystalline solar cells, the polycrystalline solar cell was the most common solar panels on the market in 2011. The market is, however, shifting to make way for the thin-film solar cell. (Kosyachenko, 2011)

Yet another reason why the growth of solar power is not very fast is the large consumption of materials during the production of solar cells. Due to the fact that silicon is an indirect semiconductor a significant thickness of the plate, in a crystalline solar cell, is needed for total absorption of solar radiation.

(Kosyachenko, 2011) The increased amount of production of solar cells causes a shortage of silicon. To save the silicon material thinner layers need to be used in the solar cells. (Brendel, 2011) The amount of material used also directly affects the cost of the manufacture (Kosyachenko, 2011). The thin-film solar cell uses a smaller amount of silicon, and the purification process is not as complicated as that for the crystalline solar cells. The lower amount of material used, and the lower production costs are two of the main reasons why this type of solar cell is growing on the market today. (Brendel, 2011)

The cost of solar cells is also decreasing because of the increased number of manufacturers and the improvement in the manufacturing process. Solar cells are now, therefore, even economically accessible to the individual villa owner in the western countries. Initiatives like competitions between countries about who will be first with a specific amount of solar powered small houses have come up because of this.

These have raised the industry’s confidence in the solar cell technology, which in its turn has increased the production even more. (Green et al., 2002)

Even though the price for solar cells is getting lower, however, not very many office buildings in Sweden are being equipped with solar panels. The reasons for this can be that there is a lack of knowledge about

solar cells in the building industry. This can be both about how they work and the benefits of them, as well as how the procedure of investing in and installing them works. Many times, solar cells are brought in at the wrong point in the building process, often too late. This can lead to higher costs of the investment due to expensive technical solutions that become necessary if, for example the space on the roof where the panels are often placed, is used for installation and fan rooms. To hold budget the solar cells might, therefore, even be taken out of the project completely. Obstacles for architects can be that they lack knowledge about what products there are and what design possibilities they offer. Buyers might be skeptical due to insecurities about the quality of solar cells and their effect on people and the environment.

Ignorance and lack of good experience feedback might also lead to solar cells getting a bad reputation.

Unprofitable existing projects can lead to the belief that solar cells are not profitable. Many buildings with solar cells have a higher cost structure and different systems than “regular” buildings in Sweden, because they are promoted as specialty buildings. Thus, they do not work well as case studies, as they are not comparable to regular buildings. Good examples on successful solar power projects is, hence, a scarce commodity, as is experience feedback from them. (Fahlén et al., 2015)

As electricity generated from solar power is more expensive than that of conventional methods, numerous countries have systems in place to promote the use of solar power. For example, the cities Burgdorf, Switzerland, and Aachen, Germany, use a tax-based system where the users have the opportunity to choose if they want to support renewable resources. If they choose to do so their electrical bill will be increased with about one percent. This percent then goes to the overcharge of electricity from private owned generators of renewable resources. (Green et al., 2002) Other systems involve the subvention from the government of solar cell investments (Fahlén et al., 2015)

In Sweden, the laws and regulations about taxes are open for interpretation and can often be considered as unclear. Because the laws on taxes for the sale of electricity to a customer or connecting to the electricity grid are both complicated and changeable, a long-term investment of a solar cell facility can seem insecure.

What is more, the relatively long payback time of a solar cell investment causes it to be considered as not profitable enough. Since the solar cells do not give any direct output to the building companies, together with the fact that the building industry is so conservative, it does not yet pose as a natural part in projects.

To raise the profitability of solar cells investments and thus, most likely, increase the number of builders willing to take the risk and invest in solar cells, the government could introduce, for example, tax subventions and research support. (Fahlén et al., 2015)

To contribute to the switch in the energy system toward environmentally friendly energy, the Swedish government has deposited funds for support for solar cells. The investment support can be applied for by public organizations, companies and private individuals. From the first of January 2018 the support for all appliers is a maximum of 30 percent and is decided by the eligible installation costs. A solar plant can get up to 1,2 million kroners in support, and the eligible cost can have a maximum of 37 000 kroners plus VAT per kilowatts peak installed. (Gustafsson, 2018)

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CASE STUDIES

For a deeper understanding of the use of solar cells and how they can be integrated in the design to increase their intake of the sun, several case studies are conducted. The buildings studied are chosen because of their unique or innovative use of solar cells and or their close emplacement to the site of the design proposal.

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The Endesa Pavilion

The Endesa Pavilion was built in 2011 by architects Rodrigo Rubio and Miguel Guerrero at the Institute for Advanced Architecture of Catalonia. The building sits on the Marina Dock in Barcelona, Spain, and is a self-sufficient solar prototype. The project was created as part of the International BCN Smart City Congress, and stood for a year working as a control room for the testing and monitoring of other projects with connection to intelligent power management (Institute for Advanced Architecture of Catalonia, 2012).

The building consists of a cuboid with shard like modules shooting out from its facades. These components, which are triangular from a section view, have photovoltaic solar cells placed on their upward facing edges.

The size and placement of the components was devised to maximize the intake of solar energy. The angle of the panels, and so also the modules, therefore depend on their orientation compared with the sun, and the relationship with the surrounding environment. (Contemporist, 2012) The form follows the energy and the façade is therefore more open and active toward the south and more closed and protected in the north (Institute for Advanced Architecture of Catalonia, 2012).

Besides capturing solar energy and protecting from solar radiation, the modules also act as storage space, allowing the remaining space to be obstacle free (Contemporist, 2012). This increases the amount of livable area without increasing the buildings footprint (Hudson, 2012). At night the pavilion is illuminated by lighting fixtures also placed in the façade modules (Vanhemert, 2012).

On the southern façades, the modules are adapted to the summer and winter sun. Here windows are placed underneath most of the modules. During summer, when the inclination of the sun is 70 degrees at its highest, the modules act like visors shading the windows, keeping the interior cool. The winter sun has a maximum inclination of about 30 degrees. The components thus allow the sun to hit the windows during winter, permitting heat gain. (Contemporist, 2012)

Figure 7: Entrance View of the Endesa Pavilion, (Adrià Goula, 2012)

Figure 8: Overview of Modules on the Endesa Pavilion, (Adrià Goula, 2012)

Figure 9: Side View of Modules on the Endesa Pavilion, (Adrià Goula, 2012)

Figure 10: Façade View of the Endesa Pavilion, (Adrià Goula, 2012)