International Journal of Sustainable Energy, Volume 29 Issue 4 2010

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Performance and economic evaluation of the first grid-connectedinstallation in Colombia, over 4 years of continuous operationA. J. Aristizábala; E. Banguerob; G. Gordillob

a Departamento de Ingeniería Electrónica, Universidad Central, Bogotá, Colombia b Departamento deFísica, Universidad Nacional de Colombia, Bogotá, Colombia

First published on: 28 May 2010

To cite this Article Aristizábal, A. J. , Banguero, E. and Gordillo, G.(2010) 'Performance and economic evaluation of thefirst grid-connected installation in Colombia, over 4 years of continuous operation', International Journal of SustainableEnergy,, First published on: 28 May 2010 (iFirst)To link to this Article: DOI: 10.1080/1478646X.2010.489948URL: http://dx.doi.org/10.1080/1478646X.2010.489948

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International Journal of Sustainable EnergyiFirst, 2010, 1–13

Performance and economic evaluation of the first grid-connectedinstallation in Colombia, over 4 years of continuous operation

A.J. Aristizábala*, E. Banguerob and G. Gordillob

aDepartamento de Ingeniería Electrónica, Universidad Central, Cr. 5 21-38, Bogotá, Colombia;bDepartamento de Física, Universidad Nacional de Colombia, Cr. 30 45-03, Lab. 111B, Bogotá, Colombia

(Received 17 December 2009; final version received 21 April 2010 )

In January 2004, the Photovoltaic System Laboratory of the Universidad Nacional de Colombia installedthe first grid-connected system in the country. A sophisticated monitoring system was implemented formeasuring and analysing the performance and power quality of the building-integrated photovoltaic (BIPV)system. The meteorological and solar radiation data at the site of installation were also analysed forcorrelation with system performance. On the basis of 4-year monitoring results, the performance of theBIPV system was analysed from a component perspective (photovoltaic array and power conditioningunit) and global perspective (system efficiency, electrical energy, power quality, etc.). Energy analysis andeconomic evaluation revealed that, to get a trade-off between energy and economic viability, the BIPVsystem installations must be heavily subsidized.

Keywords: monitoring system; photovoltaics; solar irradiance; BIPV system; virtual instruments

1. Introduction

Development of photovoltaic (PV) systems has been increasing worldwide since PV systems havebecome widespread, as a result of more active governmental policies towards renewable energysources (Hashimoto 2003, Weiss et al. 2003, Palz 2006, Protogeropoulos 2006) and also due tothe fact that PV generation has a far smaller impact on the environment than traditional methodsof electricity generation (Zweibel 1990).

At present, the cost of PV generation in Colombia is higher than that of conventional generation;however, Colombia’s complex topography makes the implementation of transmission and distri-bution systems in remote areas very difficult and expensive. These facts justify the use in Colombiaof distributed generation models, of which the building-integrated photovoltaic (BIPV) systemsare the most attractive representatives. Therefore, in the future, when massive grid-connectedPV systems will be interconnected with the distribution networks, the establishment of optimumdesign technologies for reliable PV systems will play an important role.

In this context, the first grid-connected BIPV system was installed in 2004, at the UniversidadNacional de Colombia, located in the city of Bogotá, Colombia, at 4◦35′ latitude and 2.580 km

*Corresponding author. Email: [email protected]

ISSN 1478-6451 print/ISSN 1478-646X online© 2010 Taylor & FrancisDOI: 10.1080/1478646X.2010.489948http://www.informaworld.com

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2 A.J. Aristizábal et al.

altitude. Until now, the PV plant has been operating continuously and its performance has beenreliable. A sophisticated monitoring system has been implemented and installed, to measure andanalyse the general performance of the PV system as well as to investigate the influence ofthe meteorological conditions on its operational characteristics. Based on the 4-year monitoringresults, the performance of the BIPV system has been analysed for component perspective (PVarray and power conditioning unit (PCU)) and global perspective (system efficiency, electricalenergy, power quality, etc.). An energy analysis and economic evaluation allowed us to establishthat, to get a trade-off between energy and economic viability, the BIPV system installations mustbe heavily subsidized.

2. System description

The grid-connected BIPV system, installed at the Universidad Nacional de Colombia, includesa PV array of 12 modules of crystalline silicon (BP Solar-270F), each one of 70 Wp and a PCUXantrex Sun Tie-1000 model of 1000 W. Since the DC input of the ST-1000 inverter is between 48and 85V and the voltage at the maximum power point (VMPP) of the module is 17V, the PV arraywas built interconnecting four modules in series and three in parallel. Under these conditions, thenominal power of the PV array is around 840 Wp.

Figure 1 shows a diagram of the whole system including the monitoring system. The electricalenergy was measured using three two-phase energy meters. M1 measures the electric energygenerated by the PV array, M2 measures the energy imported from the grid to the building andM3 is a bidirectional meter which measures the difference between the energy consumed and theenergy produced by the PV plant that returns to the grid.

The PV system is fully monitored and supervised to evaluate and analyse the general perfor-mance and the power quality of the PV system. For that, the following items were measured fromJanuary 2005 to today:

• DC power supply by the PV array and AC power supply by the PV system.• Inverter efficiency and system conversion efficiency.• Electric energy generated by the PV array and electric energy produced by the BIPV system

which is exported to the grid.

Figure 1. Block diagram of the grid-connected system, including the devices constituting the monitoring system.


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• Parameters determining the power quality (% total harmonic distortion (THD), harmonic com-ponents, frequency, voltage, flickers, power factor, active power, apparent power and reactivepower).

• Global solar irradiance in the inclination plane of the panels and ambient temperature.

3. Monitoring system

3.1. Data acquisition system

The monitoring system was developed using the virtual instrumentation concept (Bishop 2007).For that, a data acquisition board and the signal conditioning extensions interfaces (SCXI) systemof the National Instruments Company were used as hardware and the Laboratory Virtual Instru-ment Engineering Workbench (LabVIEW) package (The Institute of Electrical and ElectronicsEngineers 2000) was used as software. The system includes also sensors and transducers formeasuring the parameters required to determine the performance and the power quality of the PV-system. Figure 2 displays a block diagram of the system used to monitor the general performanceand power quality of the BIPV system. The equipment implemented to analyse the power qualitygenerated by the PV system was developed taking into account the IEEE standard 929-2000 (TheInstitute of Electrical and Electronics Engineers 1992).

The technical specifications of the sensors, transducer and devices constituting the monitoringsystem are as follows.

(i) Solar irradiance sensor: Piranometer Kipp and Zonen SP-LITE (response time <1 s, sensi-tivity of 72 μV/W/m2, spectral range 0.4–1.1 μm, stability < ±2%/year, nonlinearity <1%up to 1000 W/m2).

(ii) Temperature sensor: 10k Thermistor (time constant of 2.5 s, dissipation constant of8 mW/◦C, tolerance 0–70◦).

(iii) DC current transducer: FLUKE i410 DC Clamp (output signal, 1 mV/amp, working voltage600Vrms, load impedance >1 M�//100 pF, DC accuracy 3.5% + 0.5A (0–400A).

(iv) AC current transducer: FLUKE i200s AC clamp (load impedance >1 M�//100 pF, crestfactor <3, output signal 100 mV/A, accuracy <2%+5A, current range: 0–200A).

Figure 2. Block diagram of the monitoring system.



Figure 3. SCXI data acquisition system.

(iv) Data acquisition system: Figure 3 shows a block diagram of the data acquisition system.This is formed by the following devices.• Analogue inputs module SCXI-1125: It consists of eight programmable isolation ampli-

fiers. Each channel can be programmed independently, for input ranges from ±2.5 mVto ±5V. With the SCXI-1313 high-voltage attenuator terminal block, the input rangeis extended to ±300V. Each channel includes a programmable low-pass filter that canbe configured for 4 Hz or 10 kHz. Each channel is individually isolated with a workingcommon-mode voltage of 300Vrms between channels or channel to ground.

• High-voltage attenuator terminal block SCXI-1313: It is shielded and has screw terminalsthat connect to the SCXI-1125 input connector. Each SCXI-1313 channel has a precisionof 100:1 resistive voltage divider that can be used to measure voltages of up to 300Vrms

or ±300VDC with the SCXI-1125. The user can individually bypass these dividers forlow-voltage measurement applications. The terminal block has 18 screw terminals foreasy signal connection. One pair of screw terminals connects to the SCXI-1125 chassisground. When used with the SCXI-1125, the remaining eight pairs of screw terminalsconnect signals to the eight analogue inputs.

• SCXI 1000 chassis: It includes circuits to control the SCXI-1313 and SCXI-1125 modules,supply the power for the operation of the SCXI system and provide a low noise ambientfor signal conditioning.

• DAQ PCI-6221: Sixteen analogue inputs at 833 kS/s, two analogue outputs, 16-bitresolution, nominal range ±10V.

3.2. Virtual instruments

The signal measuring and the acquisition, processing, storing and reporting of the whole data wereachieved through a virtual instrument (VI) developed with the help of the LabVIEW package.The data were stored in the computer hard disk in a universal format, allowing their subsequentprocessing with LabVIEW or any other known electronic spreadsheet.

The monitoring of the whole system was performed with several sub-VIs, which are integratedto the main VI through the source code contained in the block diagram. The numerical data and



graphics generated with each sub-VI can be visualized on the computer screen by activatinga window displayed in the upper side of the frontal panel of the main VI. The sub-VIs weimplemented for monitoring the PV plant are given as follows.

3.2.1. VI for monitoring system variables

This VI allows measuring the AC voltage and current signals generated by the inverter, andvisualizing them in the front panel as well as the corresponding rms values.

3.2.2. VI for monitoring the power quality of the BIPV system

This sub-VI allows measuring and processing the AC voltage and current signals to analyse thepower quality, according to IEEE 929-2000 Standard. They are %THD, harmonic components,frequency, voltage, flickers and power factor. To carry out a deeper analysis of the power quality,the VI was furnished with tools to measure additional parameters dealing with the diagnosis.They are active power, apparent power, reactive power, distortion, k factor, peak factor, shapeand telephone interference factor. Harmonic components were determined through the Fourieranalysis of the AC signal generated by the inverter, carried out using a tool available in theLabVIEW package.

3.2.3. VI for monitoring the PCU efficiency

This VI picks up the DC current and voltage values at the PCU’s input as well as the currentand voltage at the PCU’s output; next, through proper processing, it determines the inverter’sefficiency. This VI determines the PV array efficiency as well.

3.2.4. VI for monitoring the solar irradiance and ambient temperature

This VI has been implemented for measuring the global solar irradiance and ambient temperatureat a rate of 1 datum/s, followed by storage of the mean value calculated over 1 min. Additionally,the VI allows displaying numerical data and graphics of the irradiance and temperature dailyvariations (between 5 am and 7 pm) on the computer screen. The data are stored in an Excel formatand processed to provide information concerning the mean (daily, monthly, yearly) irradiance andambient temperature, as well as the number of hours of standard irradiance.

4. PV system performance results

4.1. PV array performance

The PV system was monitored from January 2005 to present. The main performance monitoringresults of the PV array are shown in Figures 4 and 5.

The main features of the results in Figures 4 and 5 are as follows.

• The total output energy generated by the PV array during the first 4 years was about4461.4 kWh/year, with average daily energies of 39.98, 37.05, 34.9 and 36.78 kWh during2005–2008, respectively.



Figure 4. Yearly profile of the mean daily DC energy production of the PV array in Bogotá, together with the PV arrayconversion efficiency for each month of years 2005–2008.

Figure 5. Yearly profile of the mean daily solar radiation in Bogotá, together with the mean daily ambient temperature,in Bogotá for each month of years 2005–2008.

• The conversion efficiency of the PV array varied from 10.3 to 12.2%, due to the nonlinearbehaviour of the I–V characteristic of the PV array under the meteorological conditions of thesite and also because the conversion efficiency depends on the module temperature.

• February and September are in general the months with the highest solar irradiance in Bogotá,with values of around 4000 Wh/m2-day, whereas April and May are the months with the lowest



Figure 6. Variation of the efficiency of the ST-1000 PCU as a function of the input power level.

average of daily irradiance, with values around 2500 Wh/m2-day. These results also revealedthat the annual daily averages of solar irradiance in Bogotá, during 2005–2008, were 3635.8,3169.1, 3904.2 and 3542.6 Wh/m2-day, respectively, which are values relatively low for aregion near the equator. This particular behaviour seems to arise from the fact that Bogotá islocated in the Andean Range, characterized by sudden atmospheric changes and intermittentcloud cover.

• The annual daily averages of ambient temperature in Bogotá were 14.76, 13.69, 16.75 and16.14◦C in 2005–2008, respectively, with a variation range between 13 and 17.5◦C.

4.2. PCU performance

Figure 6 shows the variation of the efficiency of the ST-1000 PCU as a function of the input powerlevel, over a range varying between 50 and 750 W. Figure 7 compares the average values of themonthly efficiency of the PCU, calculated from data obtained during years 2005–2008.

The results of Figure 6 show that the ST-1000 inverter achieves an overall efficiency of 90%above 500 W; however, the efficiency decreases significantly when this power level decreases,indicating that the maximum efficiency of the ST-1000 inverter can be achieved when the inputpower is close to its nominal value. On the other hand, it is observed that the behaviour of theefficiency vs. power level curve is different from that reported by the manufacturer for the ST-series inverters (Trace Engineering, 2000), probably as a consequence of the incorporation of atransformer to fit the PCU output voltage to the nominal voltage of the grid. The results of Figure 7reveal that the monthly average of the inverter’s efficiency over the 4 years of monitoring is about83%, varying between 76 and 88.6%.

4.3. PV system performance

Figure 8 displays the variation of the average values of daily AC energy production of the BIPVsystem, together with the average values of the system efficiency, for each month of years 2005–2008, respectively. The main features of these results are the following.

• The highest value of daily AC energy production was of 4.1 kWh-day, which was registeredin January 2006, whereas the lowest value of daily AC energy production was 1.5 kWh-day,registered in April 2007.



Figure 7. Average values of the monthly efficiency of the ST-1000 PCU over 4 years of monitoring period.

Figure 8. Daily AC energy production of the PV system together with the system efficiency, for each month of the years2005–2008.


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Table 1. Values of total energy produced by the BIPV system, global irradiance and the parameters YR, YF and PR, for each month of years 2005–2008.

AC energy (kWh) Irradiance (kWh/m2) YA YF YR PR(%)

Month 2005 2006 2007 2008 2005 2006 2007 2008 2005 2006 2007 2008 2005 2006 2007 2008 2005 2006 2007 2008 2005 2006 2007 2008

Jan 62.9 60.4 39.1 44.2 4.43 3.68 4.06 3.98 98.063 100.3 171.9 123.89 74.88 71.9 46.54 55.1 124 110 122 119 0.6 0.65 0.38 0.46Feb 46.4 40.2 83.5 56.3 3.52 4.07 5.91 4.57 120.23 175.3 150.23 165.78 55.24 47.9 99.4 67.45 109 122 177 137 0.51 0.39 0.56 0.49Mar 43.1 38.7 83.1 67.4 3.32 2.67 3.31 3.89 115.45 131.25 132.78 124.67 51.31 46.1 98.92 78.78 100 80.1 99 117 0.52 0.57 0.88 0.68Apr 42.6 35.2 46.1 34.1 3.25 2.64 3.17 2.79 130.54 106.38 96.84 110.32 50.71 41.9 54.88 44.8 101 79.2 95 83.8 0.5 0.53 0.57 0.53May 48.5 40.1 41.6 38.9 3.6 2.62 2.85 2.42 165.74 91.4 91.55 94.54 57.74 47.7 49.52 49.69 108 78.69 86 72.7 0.53 0.6 0.57 0.68Jun 54.2 53.7 61.3 43.6 3.42 3.1 3.01 3.83 144.45 104.22 95.77 102.3 64.52 63.9 72.97 54.49 106 93 90 115 0.61 0.68 0.8 0.47Jul 59.5 56.8 30.4 52.5 4.04 3.48 3.13 4.17 155.41 129.29 106.84 136.8 70.83 67.6 36.19 63.57 121 104 94 125 0.58 0.65 0.38 0.51Aug 40.7 35.4 49.4 41.3 6.65 3.36 4.49 4.54 127.23 134.7 128.5 132.6 48.45 42.1 58.8 52.14 110 100 135 136 0.44 0.42 0.43 0.38Sept 48.7 46.5 52.1 40.2 3.06 3.63 5.11 5.59 94.78 121.81 122.18 128.4 57.98 55.4 62.02 51.02 95 109 153 168 0.61 0.5 0.4 0.3Oct 52.7 42.1 41 39.8 3.77 2.6 2.96 5.12 159.23 146.9 96.96 136.2 62.74 50.1 48.8 50.61 113 78 89 153 0.55 0.64 0.54 0.33Nov 68.4 59.1 54.1 56.5 4.39 2.76 4.38 3.54 95.54 156.9 125.29 112.1 81.43 70.4 64.4 67.65 136 83 131 106 0.6 0.84 0.49 0.64Dec 57.2 54.5 58.2 58.4 4.43 3.35 4.47 3.94 132.78 163 97.31 154.2 68.1 64.9 69.28 69.59 137 100 134 118 0.5 0.65 0.51 0.59

Total 624.9 562.7 639.9 573.2 47.88 37.96 46.85 48.4 1359.4 1561.4 1416.2 1521.8 743.9 670 761.7 704.9 1360 1137 1405 1452



• The total accumulated energy generated by BIPV system during the years 2005–2008 was624.9, 562.7, 639.9 and 573.2 kWh-year, respectively, with a mean daily energy produced overthe 4 years of 2.75 kWh/day.

• The conversion efficiency of the BIPV system varied between 8.2 and 10.9 % and its mean valueover the 4 years of monitoring was 9.4%. The low values of the BIPV system efficiencies, whencompared with those of the PV generator, is caused by losses associated with power dissipationin wires which transport the current between PV generator and PCU, as well as with lossesproduced during DC to AC power conversion and those caused by under-sizing of the PVgenerator.

The performance of the PV system was analysed using the European Guidelines Document(Commission of the European Communities 1997) and the IEC Standard 61724 (InternationalElectrotechnical Commission 1998). Key parameters are: energy yields (PV generator yields YA,reference yield YR, final yield YF) and performance ratio (PR = YF/YR). Reference yield is definedas the solar irradiance in the inclination plane of the PV generator in a frame of time, dividedby the solar irradiance under standard conditions (de Cardona and López 1999). Final yield isdefined as the energy generated by the system in a period of time, divided by the nominal powerof the PV generator.

Table 1 lists the values of the AC energy produced by the BIPV plant and of parameters YA,YR, YF and PR, for each month of years 2005–2008.

The total annual final yield for the PV plant installed at the Universidad Nacional de Colombiawas 743.93, 669.8, 761.7 and 704.9 kWh/kWp-year for 2005–2008, respectively. The first, thirdand fourth values are in accordance with those obtained for grid-connected PV systems installedin several IEA-PVPS countries, which vary between 700 and 1840 kWh/kWp-year (Jahn andNasse 2002).

The calculated performance ratio of the PV system varied between 0.38 and 0.88 during the4 years we monitored it. Those low values of YF and PR obtained for the PV system installed inColombia could be attributed to the power losses caused by the incorporation of a transformerbetween the PCU and the common coupling point (CCP), used to fit the inverter output voltage(220–240VAC) to the nominal voltage of the grid (208VAC), and to the low PCU efficiency causedby the under-sizing of the PV array.

It is observed that, in general, the difference between YA and YF, known as capture losses(Jahn and Nasse 2002) is too high; this behaviour is basically caused by the incorporation of thetransformer used to fit the PCU output voltage to the nominal voltage of the grid.

5. Power-quality results

The quality of the electric power generated by the grid-connected PV system was studiedthrough measurements carried out during the 4 years of monitoring. The results indicate thatthe power generated by the PV system fulfilled all the requirements demanded by the existingnational and international standards and regulations. The quality parameters analysed showed thefollowing values.

• No flickers were ever present.• The operating voltage was always between the values established by the standard. The output

voltage of the PV system varied between 95 and 103% of the nominal voltage.• The frequency was always according to the standard. The highest registered frequency was

60.001 Hz and the lowest 59.998 Hz.• The lowest power factor was 0.925.• The highest %THD was 4.16%.



Table 2. Installation costs and money saved during the 4 years of operation.

Money saved: first 4 yearsInstallation costs (US$) US$/kWh of operation (US$)

PV generator 6.500 0.15 950Inverter 1.600Other costs (structure, distribution

board, electrical ground connections,energy meters, labour etc.)

2.200

Total installation costs 10.300

6. Economic evaluation

Previous to the economic evaluation of the installed PV power plant, we will give informationregarding the installation’s costs and the economic benefits determined by money saved along the4 years of operation, assuming the tariff for residences of strata 5 and 6 (Table 2).

The profitability and economic viability of any power supply technology is determined by thenet present value (NPV) and its ability to produce electrical energy at a cost than can competewith other generation sources.

The profitability and economic viability of any power supply technology is determined by theNPV and its ability to produce electrical energy at a competitive cost.

To establish if the electrical energy produced in Colombia with BIPV systems is economicallycompetitive with the energy generated through conventional sources, it is necessary to comparethe mean cost of PV energy (Cme) with the current average tariff in the country.

For grid-connected PV systems, the NPV and the mean cost of PV energy (Cme) calculated foran installation of 1 kWp are given by the following relations (Caamaño 1998)

NPVkWp = Pnom.G · YF · FA(rre, N) · per · (FP + (1 − FP) · (y(x)/x))

CGkWp · (1 + FDI · FCI + Finst. − FCE)

− pnom.G · (Ffin + fOMS · FA(r, N)) (1)

with

x = EFV

Ecand y(x) = EER(x)

Ec+ 1

Cme = CkWP · x · [Ffin + fOMS · FA(r, N)]YF · N

+ per · [1 − FP · x + (FP − 1) · y(x)](2)

where Pnom.G is the nominal power of the PV generator, FA(rre, N ) the actualization factor oftotal profit, 1 year after initial outlay (depends on discount rate rre and lifetime N ), per the energypurchase price, pvr the energy sale price, FP the pvr/per, EFV the energy generated by the PVsystem, EER the energy imported from the grid, EC the energy consumed by the load, Ffin thecosts associated to financing mechanisms, taxes, subsidies, depreciation, etc., fOMS the costs ofoperation and maintenance of the PV system, CGkW the cost of PV generator, FDI the PCU sizingfactor, FCI the cost of PCU to cost of PV generator ratio and Fins the costs of installation of thePV system.

Since in Colombia there are no subsidies for investments in renewable energy projects, orregulatory norms giving economical incentives to investments in PV generation, as those adoptedin Europe, at present the cost of PV generation in Colombia is not competitive with the conventionalenergy sources.



Figure 9. Variation of (a) NPV and (b) mean cost of energy as a function of the subsidy to the initial inversion. FactorFP as the parameter.

From an energy analysis and economic evaluation of the BIPV system we installed in BogotáColombia, carried out through calculations of the NPV and the mean cost of PV energy (Cme),using experimental data obtained during the 4-year monitoring period, we have established underwhat conditions a BIPV system project could be profitable and competitive with conventionalelectricity generation.

Figure 9 shows the NPV and the mean cost of energy (Cme) in dependence of the subsidy givento both, the initial investment and surplus of kWh photovoltaically generated, determined by thefactor FP.

The results of Figure 9 show that the economic viability of the operation of a BIPV system isachieved if the initial inversion is subsidized in an amount greater than 50% and the surplus of kWhphotovoltaically generated subsidized in an amount corresponding to FP > 3. On the other hand,taking into account that the residential tariff in Bogotá (for stratum 4) is 0.15 USD, Figure 9(b)shows that the PV generation is economically competitive with the conventional generation if theinitial inversion is subsidized in an amount greater than 50% and the surplus of kWh is subsidizedin an amount corresponding to a FP = 3.



At present, the PV generation in urban areas of Colombia is more expensive than theconventional generation; however, PV generation is most competitive in remote areas wheresmall amounts of energy are required far from the grid, because the implementation of transmis-sion and distribution systems in remote sites demands very high investments. As well as economicbenefits, there are also social and environmental benefits which should be taken into account whenchoosing between systems.

7. Conclusions

Results of operational performance of the first grid-connected BIPV system installed in Colombia(located in Bogotá, at 4◦35′ latitude and 2.580 m altitude) over 4 years of monitoring time wereobtained with a sophisticated monitoring system, designed and implemented by us using thevirtual instrumentation concept. These results allowed evaluating the general performance andthe quality of the electric power generated by the PV plant.

Through an energy analysis and economic evaluation of the performance of the installed BIPVsystem, carried out through calculations of the NPV and the mean cost of PV energy (Cme),using experimental data obtained during the 4-year monitoring period, we have established thatthe economic viability and the ability to produce electricity at a cost that can compete withthe conventional generation are achieved if the initial investment is subsidized in an amountgreater than 50% and the surplus of kWh photovoltaically generated is subsidized in an amountcorresponding to FP > 3.

Acknowledgement

This work was carried out with the financial support from COLCIENCIAS and the Universidad Nacional de Colombia.

References

Bishop, R., 2007. Learning with LabVIEW 8. 1st ed. Boston: Prentice Hall.Caamaño, E., 1998. Edificios Fotovoltaicos Conectados a la Red Eléctrica: Caracterización y Análisis, Tesis Doctoral.

Universidad Politécnica de Madrid, Escuela Técnica Superior de Ingenieros de Telecomunicaciones, Madrid, España.Commission of the European Communities, 1997. Guidelines for the assessment of photovoltaic plants. Paris: Doubleday,

Document B, version 4.3.de Cardona, S. and López, Ll., 1999. A general multivariate qualitative model for sizing stand alone photovoltaic systems.

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Protogeropoulos, C., 2006. The new law for renewable energy sources in Greece and measures for the developmentof photovoltaic applications in the country. In: 21st European photovoltaic solar energy conference, EuropeanCommission, 4–8 September 2006, Dresden, Germany. Munich: WIP Renewable Energies, pp. 2913–2918.

The Institute of Electrical and Electronics Engineers, 1992. IEEE recommended practices and requirements for harmoniccontrol in electrical power systems. IEEE Std. 519-1992. New York: IEEE-SA Standards Board.

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