PV IN BUILDINGS FOR MALAYSIA-PROTOTYPE SOLAR HOUSE

PV IN BUILDINGS FOR MALAYSIA: PROTOTYPE SOLAR HOUSELim Chin HawNLCC Architects Sdn Bhd,33-1, Jalan Ara SD 7/3B, Bandar Sri Damansara, 52200 Kuala Lumpur, Malaysia ABSTRACTMost PV installations in Malaysia so far are standalone systems. Grid-connected PV started with some test installations recently. The “Prototype Solar House” located near Kuala Lumpur was built in 2002 as part of an Industry Research and development Grant Scheme (IGS) project. It is unique, since in a typical residential house 3 different grid-connected roof installation with different PV generators (polycrystalline, monocrystalline, amorphous silicon; standard mounting, integration, roof tiles) have been built with emphasis also on architecture and thermal aspects. An innovative monitoring system allows assessing all relevant operating parameters for the PV systems. The installations run very reliable with high efficiency, but some grid specific aspects have been found relevant for proper functioning of grid-connected PV systems in Malaysia. 1. INTRODUCTIONUntil now, most applications of PV technology in Malaysia are concentrating on stand-alone systems. Because Malaysia is located just north of the Equator, there is a high annual irradiation and simulation calculations lead to an expected AC energy output for ideally orientated grid-connected PV systems of around 1200 ... 1300 kWh/kWp [1]. Therefore grid connected PV represents one proper option to contribute to the mix of future energy sources in Malaysia. First demonstration projects on grid-connected PV have been started during the last years [2]. The project “Prototype Solar House” is funded by the Ministry of Science, Technology and the Environment of Malaysia through the Industry Research and Development Grant Scheme (IGS). The project is implemented through joint cooperation between NLCC Architects of Malaysia and Fraunhofer ISE Germany. Under the grant scheme, the Prototype Solar House has been designed and built to demonstrate different Photovoltaic technologies in one living house for urban areas in Malaysia (see Fig. 1).This approach allows to directly compare the different technologies and system concepts with each other and to draw general conclusions regarding PV systems optimised for the local Malaysian conditions.2. TECHNICAL DETAILSThe Photovoltaic installation consists of three Subsystems with a total nominal power of about 3 kWp, which are shown in Fig. 3. All systems are roof-integrated, system 3 is built in a car port roof area.Generator 1 has been equipped with monocrystalline standard BP 275 modules, a module type, which is also being manufactured locally in Kuala Lumpur. The modules have been mounted using special designed mounting methods. Generator 2 was built with Thyssen Solartec® modules, which are single-layered roof elements made of steel with integrated photovoltaic modules, based on the triple-junction thin film silicon technology. Generator 3 is made of polycrystalline photovoltaic roof tiles of the type Lafarge Braas SRT 35. All three PV systems are equipped with the SMA inverter SWR 1100 E. This inverter type has been chosen because of its electrical rating (especially the comparatively broad range for the DC input voltage of 150 .. 400 V) and the availability in Malaysia. The smaller experimental installations on the bungalow besides the Solar House have been equipped with the DMI 450/35 inverter. The inverters have been mounted in a control room of the house, where also the central cabinets have been installed that connect all electric and data lines with each other or to the corresponding units (see Fig. 4).All relevant electrical and environmental data are being monitored and evaluated regularly. The measuring data are currently stored as 5 minutes averages, this value can be changed later if necessary. The overall monitoring concept was planned in a way, that an automatic data collection software is used to transfer the data files from the logger to the NLCC office. During operation it turned out, that this connection is sensitive to overvoltages induced because of thunderstormes nearby the location of the Solar House.A display showing actual and accumulated data has been designed and installed in the control room of the Solar House (see Fig. 5).3. EVALUATION RESULTS3.1 Commissioning and Start-UpAfter installation of the systems, all individual subsystems have been put into operation and checked about the electric performance and the correctness of the measuring equipment using calibrated sensors and meters. During the commissioning it turned out, that some of the inverter were not operating properly. As a reason for this it was found, that the voltage of the electricity grid at the building site for the Solar House is very much influenced by the other loads connected to the same grid segment. Since the house has been built in an industrial area, the voltage was found to be very high (more than 260V) during week-end times or during the night. Since the inverter monitor the grid voltage and switch off for security reasons for very high and very low voltages, during time of very high voltage some inverter went offline and remained in this status for some time. Fig. 6 shows this situation for a certain time period.After discussion with the inverter manufacturer, the problem was solved by adjusting the voltage range for the inverter accordingly. Even though the problem found could be solved relatively easy in the concrete case, it once more became obvious, that a proper installation of significant remote energy generators like Photovoltaic to public electricity grid requires a certain attention to be given to the concrete real parameters of the grid-interface and that a widespread implementation of distributed generators (not necessarily only Photovoltaics!) requires some investigation about the concrete grid properties for the corresponding low voltage grid types.3.2 Energy balance for one year of operationDuring the first year of operation, the total energy consumption in the solar house had been about 3600 kWh and the total energy generation of all PV system parts installed in the project had been around 4000 kWh thus exceeding the energy consumption. For a proper assessment of these values, it must be taken into account, that the Solar Building (2 storeys + attic) had not been occupied all the time but visited frequently, and that airconditioning was frequently switched on in several rooms. Even though the total energy demand was balanced with the electricity production, a significant amount of electricity consumed in the house (about 2550 kWh) was delivered by the public grid. The reason for this is the time difference between the major photovoltaic generation and the consumption of energy in the house. Therefore, more than half of the energy produced has been fed to the grid and “taken back” during different times. This result underlines the importance of the public electricity grid as a “storage” and distribution medium for energy generated by PV installations. With 1017 kWh/kWp the system part with the Thyssen modules generated the highest energy output, while the other system parts generated below 1000 kWh/kWp. The reason for the comparatively low energy output are building aspects of the solar house. The roof parts with the solar generators had to be orientated towards West leading to a loss in the expected energy output of around 100 kWh/kWp compared to South orientation. In addition, shading effects of protruding roof elements during the morning hours lead to further unavoidable energy losses.3.3 Evaluation detailsAs mentioned in Chapter 3.2, special building aspect resulted in shading effects. Fig. 7 shows exemplary, how these shading effects influence the efficiency of the solar generator (Brass Roof Tiles) as a function of irradiation. It must be pointed out, that theefficiency values of the generator efficiency have been calculated using the whole generator as reference area and must not be mixed up with the cell efficiencies, which are significantly higher!Fig. 8 shows the inverter efficiency as a function of DC Power. It can be seen, that maximum efficiency is reached under part load conditions, and that even for relatively low DC Power the efficiencies are very good (this is quite important for the PV generators at the Solar House, since part load conditions are frequently observed at this location).The average daily module temperatures are between about 32°C and 34°C with maximum values up to around 70°C and minimum values of around 23°C. There is a slight difference in the temperatures between the different roof parts depending on the building parts (highest temperature for the attic PV generator). The Performance Ratios have been found to be around 70%.Fig. 9 shows the daily specific energy yield for one system (PV roof part with Thyssen modules) and the corresponding irradiation values. Fig. 10 shows the corresponding Performance Ratios for the same PV system part and the same time period.4. CONCLUSIONOne major goal for the PV project “Prototype Solar House” had been the demonstration of a technically and architecturally sound solution for the integration of proven PV technology into typical living houses in Malaysia. The reason behind this intention was to help pave the way for the application of grid connected Photovoltaic in Malaysia and to emphasize the multi-functional aspects of PV in buildings with a concrete demonstration project. One of the most important multi-functional aspects, that could be successfully demonstrated, is the following: Photovoltaic elements can successfully be used for living houses to replace conventional building elements (like roof tile or sun shading elements) that do not only allow architecturally interesting solutions for the building view but also technically sound solutions for serving as a building element and delivering electricity at the same time. From this point of view, grid connected PV systems in buildings constitute one interesting option for a prospective mix of sustainable energy generation technologies.The evaluation of the measuring data of the Solar House shows, that all PV systems are running very reliable now and with satisfying performance. For the performance evaluation, the concrete building conditions and unavoidable location constraints must be taken into account (comparisons to performances of other systems must notice this aspect). It turned out to be important to characterise the situation about the grid interface carefully to avoid energy losses of the PV system during certain grid conditions (like overvoltages etc.). For the Solar House, during the first year of operation more energy has been produced than had been consumed in the house on an average basis. REFERENCES[1] C. Reise, T. Erge, …Solar Irradiation and Energy Yields for Photovoltaic Systems in Kuala Lumpur“, Fraunhofer ISE, January 2002 (on behalf of NLCC Architects)[2] A. H. Haris, W. F. Anwar, “Experiences in Conducting Research on Pilot Grid Connected Solar Photovoltaic Systems in Malaysia”, 17th European PV Solar Energy Conference, Munich 2001, Germany。