Category Archives: EuroSun2008-11

Which way should it face?

Influences of climate, load profile and energy storage on the optimum inclination and orientation for thermal and photovoltaic solar energy

collectors

Brian Norton

Dublin Energy Lab Dublin Institute of Technology Dublin, Ireland president@dit. ie Abstract

Climatic and operational factors influencing the optimal orientation of solar energy, primarily photovoltaic, collectors are discussed in the context of relevant previous research. An example is provided of how being in a climate with diffuse components of insolation and winter loads that are generally high gives rise to an optimal inclination with a far greater slope angle than the latitude.

Keywords: Photovoltaics, system design, climate, inclination, orientation.

1. Introduction

When building integrated photovoltaics (BIPV) walls, roofs, and awnings provide fully — integrated electricity generation while also serving as part of the weather protective building envelope [1 — 4]. BIPV can also serve as window shading devices, semi-transparent glass facades, exterior cladding panels, skylights, parapets or roofing systems [5 — 19]. BIPV system output depends on [20 — 22] (i) the availability of and access to solar radiation as determined by climate, inclination and orientation of available building surfaces [23, 24], (ii) PV efficiency and its degradation with time [25], (iii) efficiency of balance of system components. [26], coupling to the electrical network, electrical wiring resistance and voltage drop in diodes [27,28] and (iv) shading, over-shading [29] and accumulation of dirt, dust or snow.

2. Design Issues

Grid-connected PV system economic viability depends on electrical loads and utility prices [30, 31]. PV output varies according to their specific spectral selectivity as direct and diffuse insolation spectra alter with air mass and relative humidity [32; 33, 34], so better spectral matching raises PV efficiency [35]. Larger air mass at low sun angles (the incident spectrum being towards red) decreases PV efficiency. [36]. PV surface reflection loss depends orientation, inclination and location [34, 37, 38]. Measured yearly reflection losses have ranged 6.7% to 10. 8% [39, 40]. Reflection losses are lessened by the inclusion of anti­reflection coatings. Accrual of dirt on a PV surface reduces insolation transmission annually by 2% to 8% [37, 41, 42] but in dry summers could be over 20% [43; 44] depending on the PV surface, local dust sources, cleaning frequency (by rain or manually) [45] and PV surface

inclination [46]. The annual system performance ratio [1] of a roof-mounted BIPV at latitude of 54°N was 18.1% lower than the maximum [47]. At 35.7°N latitude maximum annual energy was obtained for the surface with tilt angle 29°. [48]. For both these locations, these more-inclined optimal inclinations show the contribution diffuse insolation can make to the total solar energy incident annually on a BIPV array. As illustrated in figure 1, there is a broad trend in Europe for diffuse components to be larger (i. e., the clearness index is lower) at higher latitudes [24].

image2

Figure 1. Annual variation of clearness indices with latitude for representative European

locations [24]

For seasonally-tracking arrays, annual PV output can be 94% to 96% of the maximum annual PV output when optimum tilt angle is selected only once a year and 99% of the maximum annual PV output if the optimum angle is adjusted twice a year [49]. Different methods are available to obtain optimum tilt of a PV system based on the latitude, local climates, insolation conditions and energy demand [47, 50 — 56] and location-pecific measurements have been reported of the seasonal dependence of PV system performance [57 — 64]. An autonomous solar energy system is defined as not being grid-connected: such are common from free-standing urban street furniture such as solar powered parking charge maters and solar lit and powered ticketing in bus shelters to remote systems ranging from buildings in isolated locations to solar water pumps in deserts [65 — 66]. Such systems satisfy a particular temporal load pattern in the specific weather variations associated with the prevailing climate. From a solar energy system design perspective, climate and load primarily determine the optimal inclination of collection. This interaction is, however complex as the load a function of the climate either directly or indirectly, in time or magnitude. Using a validated simulation model, the maximum annual system performance ratio of a roof mounted BIPV system at a latitude of 54°N in the UK was found to be for a south-facing surface inclined at 20°.[47]. Figure 2 shows the breakdown of influences that cause the optimal inclination in this particular example to 30° different from the latitude

Direct

The example in figure 3 does not have energy storage. The function of energy storage is to enable loads to be met by solar energy systems nocturnally and, more generally, when insolation would be insufficient. The optimal inclination with appropriately sized storage would be the optimal plane position for the collection of both the prevailing direct and diffuse insolation components. Similarly, with storage, there is seldom benefit from non-equatorial — facing (i. e., south-facing and north-facing in the northern and southern hemispheres respectively) orientations. However in applications that make transient use of solar energy such as cooking, incorrect inclination and orientation can lead to poor performance.

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65. Odeh, I., Y. Yohanis and B. Norton, Influence of pumping head, insolation & PV array size on PV water pumping system performance, Solar Energy. 80, 51-64, 2006

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Simulation based energy consumption calculation of an office building using solar-assisted air conditioning

S. Thomas* and P. Andre

Department of sciences and environmental management, University of Liege 185 Avenue de Longwy, 6700 ARLON, Belgium Corresponding Author, sebastien. thomas@ulg. ac. be

Abstract

To minimize environmental impact and CO2 production associated with air-conditioning system operation, it is reasonable to evaluate the prospects of a clean energy source. The targets of the study are to evaluate cooling energy consumption to maintain thermal comfort in an office building and to point out solar energy to satisfy these cooling needs. Simulations were carried out with three different cooling systems in the same operating conditions to determine as accurately as possible the potential use of solar energy. For comparison purpose, the base case is a classical air-conditioning system (heat pump for cooling, gas boiler for heating). Two other configurations were simulated: a classical vapour compression system fed by photovoltaic panels and electricity grid as back-up and, absorption chiller fed by solar thermal panel field and by gas boiler. In the three chosen locations (Paris, Lisbon and Stockholm), results shown that installing photovoltaic panels on the roof is really interesting from the primary energy consumption point of view.

Keywords: Solar cooling, absorption, photovoltaic, TRNSYS

1. Introduction

The present energy context is characterized by the imminent end of the era of fossil fuels and the environmental impact of their operation. Energy demand growth, local pollution, global climate change, … are problems that must be taken into account. It seems urgent to reconsider our way of life and design equipments as to minimise their energy consumption. Most air-conditioning equipments are currently electrically driven vapour compression systems. According to the International Institute of Refrigeration (IRR) [1], 15% of the world’s electricity is used for refrigeration and cooling. Moreover, the growth of cooling needs and consequently electricity consumption for cooling is an indisputable fact.

Using renewable energy such as solar energy is really feasible for air conditioning in building. Different technologies exist and can be compared based upon different characteristics: energy consumption, cost of the whole equipment, … The study is dedicated to office buildings which require especially high comfort levels and have often high heat gains due to glazed facades and electrical equipment. Small scale (round 5-10 kW) applications became recently market available. For large scale absorption and adsorption chillers the technology is more mature because of existing system driven by waste heat (coming generally from a cogeneration unit). In this work the emphasis is put on available technologies, key equipments are market available and data is taken directly from manufacturer.

The comparison exercise is realized on a theoretical office building. To point out use of solar energy in this building, three test cases have been defined. The first one is used as reference as it is a usual system implementation in real office building. For each case, three locations have been simulated using Meteonorm data files: Paris (Montsouris station), Stockholm (Arlanda station) and Lisbon.

Case

Heating

Cooling

Energy

source

Equipment

Energy source

Equipment

1

Gas

Boiler

Electricity

Vapour compression system

2

Gas

Boiler

Sun, Electricity as back-up

Vapour compression system, PV panels

3

Gas, Sun

Boiler, solar thermal panels

Sun, Gas as back-up

Absorption chiller, solar thermal panels

Table 1. Three cases heating and cooling system

Especially for the last two cases, several aspects are to be addressed in order to provide a suitable solar air conditioning solution:

• Solar collectors

• Refrigeration equipment (chiller)

• Building

• Climate

Simulation of all these elements as well as links between them requires a very flexible simulation software. The dynamic simulation environment TRNSYS [2] is applied in this study. It makes possible the whole system simulation as well as the implementation of new models.

Comparison of hot water use between different days of the week

Подпись: Mon Tue Wed Thu Fri Sat Sun Figure 6. Measured variation in energy use for hot water between different days of the week for June and October, year 2005 and 2006 respectively.

The variation in measured hot water use was also investigated on a daily basis to examine a possible difference between different days of the week. The results are found in Figure 6 for two different months the two years of available data. The trend is similar for both years and the variation between different days is small. Measured data seem to follow a similar pattern for 2005 and 2006 respectively, where the daily use is lower in 2006. Data for a certain month, however, does not coincide for the two years under investigation.

4. Discussion

The measured hot water use in the 24 apartments is similar for the two years investigated so far. The minimum in load is located in July and August, although the use is generally lower during 2006. As was also concluded in the analysis in [7] this indicates the impact of individual habits on the consumption profile. Individual habits, and the energy use in the wider context of everyday activities, can be further investigated by time diaries, which constitute the foundation of the presented model.

According to the results obtained in this study, when comparing the modelled profiles with measured, the model gives a similar, but somewhat lower hot water use. The overall load profiles, on the other hand, follow more or less the same pattern. The difference between winter time and summer time may imply that the model describes winter time better. Measurements in Malmo, Sweden, however shows morning peaks at 6-8 a. m. in weekdays and 9-10 a. m. in weekend days [9], which may indicate that the difference between summer and winter months is rather due to the routines of the particular inhabitants. The number of measured households is however too low to draw any evident conclusion.

The magnitude of the hot water use can be further compared to the study performed by the Swedish Energy Agency which shows a surprisingly low DHW use of 0.9 MWh per person and year for apartments [1]. In that study only four apartments were measured. The fact that the model predicts an energy use between that measurement study and the one investigated in this paper, and closer to the more extensive one, indicates that the model assumptions are in the right range.

The modelled profiles will be used in future studies on solar heating by introducing different profiles in dynamic simulations in the simulation tool TRNSYS. The possibility to utilize solar heat will be investigated as depending on different behaviours found in the material on time-use. Furthermore, the advantages with individual as well as joint solar heating system for a residential area will be investigated to further raise the question of tap water supply systems for low-energy buildings.

The current model only generates average profiles for one weekday and one weekend day and is not taking seasonal and weekly variations in load into account. An improvement would be to introduce those variations in the model, for example by statistical means similar to those used in Jordan et al [2]. By letting the daily individual distribution be the foundation, but vary it with day of the week and time of the year, realistic yearly profiles can be generated from single days.

More extensive measurement surveys, including a statistically significant number and distribution of households, as well as measuring hot water use in the same households as where time diaries are recorded, would be desirable to enable a more thorough validation of the model. This kind of studies are however not available at present. Although there may be deviations between the model and measurements the modelled profiles constitute an improved description of hot water use in households compared to the very simplified load profiles that are normally used.

5. Conclusion

Comparisons between modelled profiles and measurements in 24 apartments show good agreement both in magnitude and the typical distribution in time. This indicates that the model describes Swedish domestic hot water use rather well and that time-use data can be utilized for cheap and straightforward

energy estimations in households, either as an alternative, or as a complement, to detailed hot water measurements.

Detailed investigations of variations in hot water demand over the year show a clear minimum in demand during summer due to vacation periods. The average hourly distribution over the day more or less coincide between different months, and there is only a small difference in load between the days of the week, although absence and different habits seem to influence the weekly distribution between summer and autumn.

7. Acknowledgement

The work has been carried out under the auspices of The Energy Systems Programme, which is primarily financed by the Swedish Energy Agency. We also want to thank Mimer, Malarenergy, Eskilstuna Kommunfastigheter and Eskilstuna Energi och Miljo for support. Thanks to Joakim Widen, Uppsala University, for converting the original time-use data to matrixes to be used in this paper.

References

[1] Wahlstrom A, R. Nordman and U. Pettersson (2008) Matning av kall- och varmvatten i tio hushall, SP Technical Research Institute of Sweden and the Swedish Energy Agency, ER 2008:14, ISSN 1403-1892. In Swedish.

[2] Jordan U. and K. Vajen, Influence of the DHW load profile on the fractional energy savings: A case study of a solar combi-system with TRNSYS simulations, Solar Energy 69 (2000) 197-208.

[3] Wollerstrand J. (1997). District heating substations: performance, operation and design. Doctoral thesis from Department of Heat and Power Engineering, Lund Institute of Technology, Sweden.

[4] Holmberg S (1987). Flow rates and power requirements in the design of water services. Doctoral thesis from Department of Heating and Ventilation Technology, Royal Institute of Technology, Sweden.

[5] Lundh M., Wackelgard E. and K. Ellegard (2008) Design of hot water user profiles for Swedish households based on time diaries, International Conference on Green Energy with energy management and IT,

Stockholm, Sweden, March 12-13 2008.

[6] Widen J, M. Lundh, I. Vassileva, E. Dahlquist, K. Ellegard and E. Wackelgard (2008) Constructing load profiles for household electricity and hot water from time-use data — modelling approach and validation. Submitted to Energy and Buildings.

[7] Vassileva I., C. Bartusch, E. Dahlquist (2008) Differences in electricity and hot water consumption in apartments of different sizes, International Conference on Green Energy with energy management and IT, Stockholm, Sweden, March 12-13 2008.

[8] Ellegard K. and M. Cooper (2004) Complexity in daily life — a 3D visualisation showing activity patterns in their contexts. eIJTOUR (Electronic International Journal of Time Use Research), Vol 1.

[9] Bagge H. (2007) Energy Use in Multi-family Dwellings — Measurements and Methods of Analysis, Licentiate Thesis, Department of Building Physics, Lund University, Sweden.

ICS-SWH Design

The tested aluminium ICS-SWH was designed and manufactured with 3mm thick aluminium sheets incorporating fins to improve the thermal efficiency and structural stability of the heater.

Подпись: Figure 1: Solar water heater assembly, a: Plain view, b: Explode view

The water tank was placed in a hard wooden box insulated with layer of fibre glass wool on all sides and bottom as shown in Figure 1. A gap of 35mm between the absorber plate and glazing was used to reduce heat losses by restricting air movement.

HCPV system design

1.1. Concentrating and tracking system

With the intention of creating a practical and economical solar concentrator that can provide high- concentration sunlight, a parabolic dish that was developed to collect radio transmissions from cable television satellites in past has been converted into a highly reflective concentrator. The diameter of the parabolic dish is 1.2 meter and its focal length is 0.456 meter and the projected aperture area is about 1.1 square meters. As a reflecting surface we used reflecting film which is cheap and easy to buy locally.

It is well known that concentration necessarily leads to an unavoidable reduction of the angular aperture (acceptance angle) [6,7] of any collector system. Concentrators are thus limited to collecting only those rays coming from a narrow solid angle cone centre on the solar disc, i. e. mainly beam radiation. Therefore, whenever a system is intended to operate with an effective concentration ratio larger than 6 X [7], it must be provided with sun tracking to collect a reasonable fraction of this available beam radiation. Point-focus optics generally require that the concentrator track about two axes so that it is always pointed at the sun, and the focused light falls on the cell. From a mechanical standpoint, two-axis tracking is more complex than one-axis tracking; however, point focus systems are also capable of higher concentration ratio and hence lower cell cost.

A two axes sun tracking system will be applied to increase the solar system efficiency. As we know, the greater the accuracy in computing the sun position, the greater the margin of tolerance will be for other sources of error, such as optical and mechanical, that may arise within the concentrating system. Blanco et al. [8] reviewed the solar literature concerning determination of the sun position published in the last decades. In their paper, they introduced the new, more accurate and simpler algorithm that will be used here. Moreover, a programmable logic controller system will be designed and constructed.

The CPV receiver is composed of solar cells, electrical connections and vessel to provide liquid to cool the cells. The design concepts of the CPV receiver are given in Fig. 1. High performance photovoltaic cells will be used to make the system efficiency higher. Moreover, solar cells will be immersed in a dielectric liquid that will provide an effective cooling to the solar cells. The liquid enters the vessel with the temperature Tfi and leaves at the temperature Tfo. Heat from solar cells is

transferred to the liquid through convection and conduction. The size of the vessel will be changed with the solar modules to provide effective cooling.

A Gis-Based Decision Support Tool For Renewable Energy. Management And Planning In Semi-Arid Rural Environments Of

Northeast Of Brazil

Part I — General Description And Methodology

C. Tfba1*, A. L. B. Candeias2, N. Fraidenraich1, E. M. de S. Barbosa1, P. B. de Carvalho Neto3

and J. B. de Melo Filho3

1Departamento de Energia Nuclear da Universidade Federal de Pernambuco
Av. Prof. Luiz Freire, 1000 — CDU, CEP 50.740-540, Recife, Pernambuco, Brazil

2

Departamento de Engenharia Cartografica da Universidade Federal de Pernambuco
Av. Academico Helio Ramos, s/n — CDU, Recife, Pernambuco, Brazil
3Companhia Hidro Eletrica do Sao Francisco — DTG — CHESF
Rua Delmiro Gouveia, 333 — Bongi, CEP 50761-901, Recife, Pernambuco, Brazil
Corresponding Author.tiba@ufpe. br or chigueru. tiba@pa. cnpq. br

Abstract

This work describes the development of a management and planning system on a GIS (Geographic Information System) platform destined to decision makers that is, administrators, planners or consultants in renewable energies. It was conceived to deal with the management and planning of solar photovoltaic systems, biomass and aeolics in rural regions of the Northeast of Brazil. The prototype of the GIS tool covers an area of 183, 500 km2 and is made up of three principal blocks: management of installed renewable systems, inclusion (planning) of new renewable systems and updating of the data banks. The system was developed mainly for PV systems as a support tool for management and planning of the Energy Development Program for States and Municipalities (PRODEEM), a program for inclusion of large scale solar photovoltaic energy, in the rural environment, conducted by the Ministry of Mines and Energy of Brazil. Due to the limitation of space, only a general description and the methodology used for its development will be described here. A detailed description of the functionalities of the SIGA SOL 1.0 (Geographic Information System Applied to Solar Energy, in Portuguese) will be presented in Part II of this work.

Keywords: GIS, Planning and Management, Photovoltaic Energy, PRODEEM

1. Introduction

Determination of the maximum usable hot water volume

In order to evaluate the system behaviour under different draw off volumes and to determine the maximum usable hot water over a whole year, several simulations have been carried with a collector tilt angle of 42° under the climatic conditions of Rome. It has been assumed that hot water is only needed in the evening in between 6.00 — 8.00 pm. The system is included into an existing hot water system consisting e. g. of a gas boiler for hot water and room heating or a simple electronic hot water boiler.

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An automatic tempering valve at the hot water outlet of the storage prevents the users from scalding themselves. A selector valve automatically takes the hot water from the backup heating if the hot water temperature turns below 45°C. Figure 6 shows a schematic drawing of the system.

The daily draw off pattern was varied in the range of 120l/d.480l/d. As a first result of these variations it can be seen that the hot water draw off out of the 180l storage is limited to about 35,000l/a respectively the draw off gets saturated at about 240l/d, because of the climatic

conditions. With a draw off profile of only 120l/d, an annual solar hot water fraction of about 66% can be achieved. In terms of saved energy this equals a reduction of about 95l of fuel oil. With a hot water demand of 180l/d, it is still possible to cover nearly 50% of the annual hot water demand or an equivalent of 125l of fuel oil with only one collector of about 2m2 and a 180l storage tank.

4. Conclusion

The paper presents the implementation of a double mantle heat exchanger into the simulation environment CARNOT and first simulation results calculated with the new storage type.

The developed double mantle heat exchanger storage is based on the TRNSYS double mantle heat exchanger storage but was enhanced by the possibility of including user settable material and geometric data.

Concerning the system simulation, some “to dos” remain, like the validation of a modified “thermosiphonic pump”, which is able to calculate the fact of reverse thermosiphoning e. g. at night. In order to improve the system and to identify other main influencing variables, further simulation runs have to be carried out, e. g. with regard to overheating.

References

[1] S. Gurtner, F.-D. Treikauskas, W. Zorner: „Prufstand fur Thermosiphonanlage am Kompetenzzentrum Solartechnik an der Fachhochschule Ingolstadt“, 16. Symposium Thermische Solarenergie, Kloster Banz / Staffelstein (Germany), May 2006, p. 118 — 122.

[2] S. Brandmayr, W. Zorner: “Thermosiphon Systems: Market, State-of-the-Art and Trends“, 3rd European Solar Thermal Energy Conference (estec2007), Freiburg (Germany), June 2007, p. 182 — 188.

[3] N. N.: “Matlab/Simulink user manuals”, The Mathworks Inc., http://www. mathworks. com, Natick (USA), 2002.

[4] B. Hafner, J. Plettner, C. Wemhoner: “CARNOT Blockset: Conventional And Renewable eNergy systems OpTimization Blockset — User’s Guide”, Solar-Institut Julich, Aachen University of Applied Sciences (Germany), 1999.

[5] A. Carillo Andres, J. M. Cejudo Lopez: “TRNSYS model of a thermosiphon solar domestic water heater with a horizontal store and mantle heat exchanger”, Solar Energy, Vol. 72/2 (2002), p. 89 — 98.

[6] G. L. Morrison, D. B.J. Ranatunga: “Thermosyphon circulation in solar collectors”, Solar Energy, Vol. 24 (1980), p. 191 — 198.

Application of Sensitivity Analysis to Parameters of Large Solar Water Heating Systems

O. Kusyy*, K. Vajen, U. Jordan

Kassel University, Institute of Thermal Engineering, Kassel, Germany
* Corresponding Author, solar@uni-kassel. de
Abstract

In this paper the application of sensitivity analysis to the investigation of solar water heating systems is considered. Two global sensitivity analysis methods are described and applied to different solar heating systems. The first one is the Morris method that only ranks parameters by importance and the second one is the Fourier amplitude sensitivity test (FAST) that quantifies the influence of the parameters on the target functions. The both methods were implemented into the GenOpt (Generic Optimization) software and coupled with the TRNSYS simulation program.

Keywords: Sensitivity analysis, Fourier amplitude sensitivity test, Morris method

1. Introduction

In recent years, many middle to large solar heating systems were installed all around Europe and especially in Germany. A proper design of such systems is decisive for their functionality. Underdimensioning or poor selection of design parameters as well as the control strategy could lead to an overall poor efficiency of the systems. During the designing process, the advanced numerical optimization methods should be used in order to find the optimal parameter values that provide the best efficiency of the system. Considering that the target functions depend on a high number of optimization parameters and that the global optimization algorithms require large number of system simulations, the task of optimization turns to be very computationally expensive. In order to decrease the number of optimization parameters and, thus, make the optimization faster, the sensitivity analysis of parameters could be used prior to optimization. Only the most influential parameters are then selected for optimization. Another straightforward application of the sensitivity analysis is analysis of uncertainties, that is, how uncertainties in parameters influence the uncertainty of the target function. Here two sensitivity analysis methods are described and applied to the analysis of two solar heating systems. For the first system the influence of the operation parameters on the cost function is investigated by the qualitative Morris method. A more comprehensive Fourier amplitude sensitivity test is applied to the investigation of the influence of the design parameters on the solar fractional savings function of the second system. In this paper only the exemplary examples of applications of the both methods are considered. The methodological application of the methods is planned but not yet realized.

Flat plate and vacuum tube collectors

In general the output of the solar cycle is calculated using the formula:

Подпись: (1)Q = Q u — CL — Q

out abs heat pipe

The solar irradiation absorbed by the collector is:

Подпись: (2)Qabs = Edir ‘ П ‘ Aaperture ‘ F dir (0) + Ediffuse ‘ П ‘ Aaperture ‘ F diffuse

The calculation of the direct irradiance EdlI and the diffuse irradiance Ediff on the collector is based on the relevant meteorological values on the horizontal plane. Shading of the horizon can also be considered in these calculations.

The angle of incidence on the collector is [2]:

Подпись:0 = arccos(-sin^C cosys cos(aS — aC) + cosyC sinYS)

For vacuum tube collectors the angle of incidence 0 is divided into a longitudinal 0 and a transversal angle of incidence 0t referring to the collector axis According to [3] the following formulas can be used:

0 =|rC + arctan(tan(90°-ys) • cos(aS — aC)) and

arctan(cosfS • sin(aS — aC))
cos#

Подпись: 0tThe incidence angle modifier for the direct irradiance IAMdir of the vacuum tube collector is now defined by a longitudinal share IAMdirl and a transversal share IAMdir, t :

IAMdh(0) = IAM„„(А,)• IAMdlJ01).

The angles aS and yS describe the position of the sun according to DIN 5034 (aS: 0°=N, 90°=E, 180°=S, 270°=W. yS: 0°=horizontal, 90°=vertical) and aC and yC the orientation of the collector axis (aC: 0°=S, 90°=W, 180°=N, 270°=E. yC: 0°=horizontal, 90°=vertical).

The collector heat losses are calculated with the following formula:

Подпись: (6)Q heat = П • Aaperture •(k! •AT + k2 •AT2 )

The pipe losses are defined using the mean collector temperature Sc and the ambient temperature Sa as follows:

Подпись: (7)a pip,=V-te — sa )+k2′( — 20 °c)

with

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and

 

image065 image066 image067

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Typically the calculation is done for a whole year including also the night hours without heat input to the collectors. During these hours the whole system cools down and in the morning the whole system has to be heated up to design temperature. For this calculation the heat capacity of the pipes, the heat transfer fluid and the collectors are considered. Collector parameters are input values and stored in the collector database. They may be obtained from collector manufacturers or from [4].

Local management functionalities

The local management is regarded in 4 distinct blocks:

Photovoltaic systems installed in the municipality;

Identification of a determined model and manufacturer for each component;

Identification of a determined model and manufacturer of photovoltaic modules;

Operational situation of all the components of the installed photovoltaic systems;

Identification of the nearest training and maintenance center.

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image135image136(d)

Figure 3 — Macro-spatial functionalities of the SIGA-SOL, PV management by type of application and

Подпись: Ч.-Т Подпись: (b)

filtering of some specific aspects

(a)

Figure 4 — Macro-spatial functionalities of the SIGA-SOL, PV management, photovoltaic system
components and a more detailed filtering by a menu

Fig. 6 (a) shows the photovoltaic systems installed in the municipality of Ibimirim in the state of Pernambuco and in (b) which are the models of PV modules that were used in the systems. Fig. 7 (a) shows the operational state of PV system components installed in Pernambuco and in (b) the nearest maintenance centers.