1066 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 53, NO.

4, AUGUST 2006

Intelligent PV Module for Grid-Connected

PV Systems
Eduardo Román, Ricardo Alonso, Pedro Ibañez, Member, IEEE, Sabino Elorduizapatarietxe, and Damián Goitia

Abstract—Most issues carried out about building integrated enough. As a result, it becomes necessary to group PV modules
photovoltaic (PV) system performance show average losses of until the desired current and voltage levels are achieved.
about 20%–25% in electricity production. The causes are varied, The efficiency of commercial PV modules is about
e.g., mismatching losses, partial shadows, variations in current–
voltage (I–V ) characteristics of PV modules due to manufac- 14%–16%. However, PV systems show additional losses that
turing processes, differences in the orientations and inclinations are important in many cases. If not considered during the PV
of solar surfaces, and temperature effects. These losses can be design phase, unreal estimations will be foreseen, and public
decreased by means of suitable electronics. This paper presents image of PV energy could be damaged. Issues carried out by
the intelligent PV module concept, a low-cost high-efficiency dc–dc the University of Tokyo over 71 Japanese PV systems [1] have
converter with maximum power point tracking (MPPT) func-
tions, control, and power line communications (PLC). In addition, shown losses of up to 25%.
this paper analyses the alternatives for the architecture of grid- Causes are varied, ranging from load mismatching (although
connected PV systems: centralized, string, and modular topolo- most PV systems have maximum power point tracking (MPPT)
gies. The proposed system, i.e., the intelligent PV module, fits incorporated), differences in current–voltage (I–V ) character-
within this last group. Its principles of operation, as well as the istics, shadows and obscurances, dust, losses in PV inverter,
topology of boost dc–dc converter, are analyzed. Besides, a com-
parison of MPPT methods is performed, which shows the best low-radiation losses, and MPPT losses. Different European
results for the incremental conductance method. Regarding com- surveys (Netherlands and Germany are the pioneers) verify
munications, PLC in every PV module and its feasibility for these data [2].
grid-connected PV plants are considered and analyzed in this The situation of losses becomes worst in complex config-
paper. After developing an intelligent PV module (with dc–dc urations such as those integrated in roofs and facades. Great
converter) prototype, its optimal performance has been experi-
mentally confirmed by means of the PV system test platform. This number of modules brings a huge complexity, in addition to
paper describes this powerful tool especially designed to evaluate the mentioned losses in PV systems. The complexity represents
all kinds of PV systems. also an additional problem in maintenance and control opera-
Index Terms—Communication system fault diagnosis, dc–dc tions since a failure in one PV module placed at a big facade is
power conversion, frequency-shift keying (FSK), photovoltaic difficult to detect.
(PV) power systems, pulsewidth-modulated (PWM) power A predictive maintenance comprises localization and defin-
converters. ition of related faults. Localization of failures in a PV system
is very important in any condition and even more in building
I. P HOTOVOLTAIC (PV) S YSTEMS IN integrated PV (BIPV) systems. Thus, a quick detection of
B UILDING E NVIRONMENT failures would avoid energy losses due to malfunctions of PV
systems.

R ENEWABLE energy sources (RES) are considered as

a technological option for significantly contributing to
the sustainable energy supply in Europe. PV energy generates II. A LTERNATIVES FOR G RID -C ONNECTED PV S YSTEMS
electricity from solar radiation and, at present, represents one
Introduction of PV energy into the building environment is
of the RES emerging technologies due to the continuous cost
relatively novel. First, systems consisted in a great number
reduction and technological progress.
of modules, series and parallel connected to a unique large
The minimum element in the manufacturing of PV systems
inverter (central inverter). At present, technology has evolved
is the PV module. A typical panel is composed of 30–36
toward architectures consisting of a group of series-connected
series-connected solar cells, with an open-circuit voltage (Voc )
panels and a PV inverter (string technology). The number of
near 20 V and a short-circuit current (Isc ) around 3–4 A. For
modules is around 20–30 per inverter, and there will be as many
most applications, e.g., integration in building environment and
inverters as the application needs (< 5 kW per inverter). This
autonomous applications, the power of one PV module is not
architecture improves PV system performance in the presence
of irregular situations, in comparison with central inverter archi-
Manuscript received December 15, 2004; revised April 27, 2005. Abstract tecture. Mismatching and shadowing losses are reduced since
published on the Internet May 18, 2006. This paper was presented in part at
the 30th Annual Conference of the IEEE Industrial Electronics Society, Busan, the number of PV modules that work under a single MPPT
Korea, November 2–6, 2004. converter is lower.
The authors are with the Energy Unit, ROBOTIKER-TECNALIA Re- However, there are other technologies, such as those that in-
search Centre, 48170 Zamudio, Spain (e-mail: eroman@robotiker.es; ralonso@
robotiker.es; pedro@robotiker.es; sabino@robotiker.es; dgoitia@robotiker.es). corporate modules with a PV inverter—a dc–ac converter—for
Digital Object Identifier 10.1109/TIE.2006.878327 each (ac modules) [3], and their numbers are increasing. They
0278-0046/$20.00 © 2006 IEEE
ROMÁN et al.: INTELLIGENT PV MODULE FOR GRID-CONNECTED PV SYSTEMS 1067

Fig. 2. P –I characteristics of shaded and unshaded PV modules.

Fig. 1. Configurations for BIPV systems. (a) Centralized system. (b) AC

modules. (c) Modular system.

are called modular systems, and at present, they show a great

number of advantages and a few disadvantages against string
architecture. Within the field of modular systems, research
activities are focused on the dc–dc converters but applied to the
PV module [4].
Our research group is developing an intelligent PV module
that incorporates a dc–dc converter with integrated MPPT
function. Its most suitable application will be the integration
in the built environment—mainly roofs and facades—as they
seem the most complex PV systems. Fig. 3. PV series string P –I characteristics.
Fig. 1 shows the three different technologies that are consid- unshaded module (900 W/m2 ), presents a power maxima of
ered to be most suitable for BIPV applications. 82 W. However, a shaded module (500 W/m2 ), which corre-
Up to now, performed analysis shows that modular systems sponds to the dashed curve, limits its maximum output power to
have less cabling losses, although those systems are more 44 W. Additionally, note that the optimal power and current are
expensive. However, comparison between both technologies different from each other. Negative values of power in the right
cannot be made only in terms of economical reasons. There are part of the curves show the conduction of the associated bypass
also improvements in the performance of PV modular systems diodes when the passing current is greater than the short-circuit
against partial shadows or modules mismatching. current of the PV module. In this case, the PV module operates
as a load for the system, instead of as a generator, resulting in a
III. I NTELLIGENT PV M ODULES loss of power and energy.
Considering the aforementioned possibilities, this paper dis-
A. Principles of Operation
cusses the performance of two different topologies, namely
The PV array analyzed in this document consists of 20 PV 1) the centralized topology, in which all PV modules are
modules connected in series for a residential rooftop applica- connected in series to a single inverter with a centralized MPPT,
tion. Unfortunately, avoidance of partial shading in this en- and 2) the modular architecture, in which the PV array is
vironment is not always feasible. Trees, buildings, television arranged in a series string of intelligent PV modules with its
aerials, and other roof structures result in a substantial reduction own MPPT.
in system performance. In the proposed case, part of the array With the centralized MPPT, all PV modules connected in
is installed near a chimney that causes significant shading over series are forced to drive the same current. If they cannot
five of the 20 PV modules. drive this current, then their associated bypass diodes conduct.
Fig. 2 shows a Matlab simulation plot of output power for Although diodes protect PV modules from “hot-spot” effects,
an 80-W PV module (BP 580F) under two different sunlight they introduce multiple maxima on the array power–current
conditions. The solid curve, which represents the output of an P –I curve, as shown in Fig. 3, resulting in problems with
1068 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 53, NO. 4, AUGUST 2006

MPPT. Even if the MPPT reaches the greatest power maxima,

i.e., 1213 W at 4 A, the shaded PV modules would be acting as
passive loads, significantly reducing the efficiency of the whole
PV system.
With the intelligent PV modules, there is no interconnection
between PV modules, but there is interconnection between
the associated dc–dc converters. Therefore, each PV module
can operate at its own optimal power and current, and all the
available energy in the PV array can be delivered. Losses from
shading of a single PV module are limited to that module;
any unshaded modules nearby are unaffected. In the example,
whereas unshaded modules generates 82 W operating at 4 A,
shaded modules outputs 44 W at 2.25 A. Hence, PV array
supplies 1450 W, which is almost 20% more than that with the
centralized MPPT.
Fig. 4. Prototype of the intelligent PV module electronics.
Apart from shading, any other reason of mismatching be-
tween PV modules causes very minor losses and these turn
out to be more proportional to the degree of mismatching in a
modular system than for an equivalent central inverter system. used with low series resistance and equivalent series resistance
(ESR), respectively.
MPPT controllers find and maintain operation at the max-
B. Converter Topology and MPPT Strategy imum power point (MPP) using an MPPT algorithm. Many
As stated, the proposed intelligent PV module is basically a such algorithms have been proposed in the literature [5], [6].
standard PV panel incorporating a dc–dc converter with MPPT However, it is difficult to find standardized comparisons or
controller. appropriate methods for determining MPPT performance apart
With respect to the dc–dc converter topology, the boost from [7], where methods to measure the accuracy, error, and
converter, which is also known as the step-up converter, is efficiency of MPPT algorithms are presented.
considered the most advantageous in this application because Using these guidelines, a wide variety of available MPPT
of its simplicity, low cost, and high efficiency. techniques and possible modifications and improvements were
The conversion ratio between input and output voltages of the discussed. The scope of the study was limited to those algo-
ideal boost converter varies with the duty ratio D of the switch, rithms thought to be applicable to low-cost implementations
according to the following equation: with microprocessor control.
Despite their simplicity, analog methods, which use the
1 voltage and the current from the PV module directly to control
Vout = Vin .
(1 − D) the operating point, were discarded in the study due to their
excessive dependence of environmental influences. Many other
Since D ∈ [0, 1], the boost converter always provides a algorithms, like short-current pulse-based method [8] or two-
higher output voltage than its input. This characteristic is es- stage methods [9], were not simulated either because of their
pecially convenient to achieve the bus voltage required by the uncertain efficiency or clear complexity.
inverter from the output voltage of fewer PV modules and also After this first analysis, only two hill-climbing methods were
to work with lower string output currents and, consequently, to seriously considered, namely: 1) the perturb and observe (P&O)
reduce cabling losses. At worst, when a significantly shaded or method and 2) the incremental conductance method. Whereas
failed module is unable to generate the string output current, the former continues to be by far the most widely used method
this will be short circuited, and the remaining modules will be in commercial PV MPPT, the latter usually appears in the
able to reach the required string voltage. Anyway, this situation literature as a progress in efficiency. In fact, the incremental
only occurs for significant mismatches in power outputs if a conductance method was developed to avoid the drawbacks of
suitable voltage boost is being used [4]. the P&O method.
Finally, the small necessary size of its components, i.e., With the aim to realize a comparison between them, these
capacitors and inductor, to manage power of up to 100 W makes two optimized algorithms were simulated bearing in mind the
boost converter suitable to be mounted behind the PV panel available hardware and its limitations, such as the resolution
most likely in its junction box. Fig. 4 shows the aspect of a of measurements or the precision in the control of the signal
prototype of the intelligent PV module electronics. pulsewidth modulation (PWM).
The components of the dc–dc converter have been care- Matlab simulation results show a bit better performance ob-
fully selected trying to enhance their performance. Thus, both tained with the incremental conductance method under random
the MOSFET STP50NE10L (100 V, 50 A, 20 mΩ) and the variations of insolation, temperature, and charge. Fig. 5 shows
Schottky diode MBR1060 (60 V, 10 A) have been chosen to that the incremental conductance method (solid line) reaches
minimize conduction and switching losses since these cause the optimal operating point more quickly than the improved
most of them. Additionally, inductor and capacitors have been P&O method (dashed line) and, moreover, eliminates the
ROMÁN et al.: INTELLIGENT PV MODULE FOR GRID-CONNECTED PV SYSTEMS 1069

Fig. 5. Efficiency of MPPT algorithms: incremental conductance method and

P&O method. Fig. 6. Experimentally measured efficiency of the intelligent PV module.

continuous oscillation of the operating point around the point

of maximum power.
The incremental conductance method is based on the fact that
the derivative of the output power P with respect to the panel
voltage V is equal to zero at the MPP. The P –V characteristics
in Fig. 2 show further that the derivative is greater than zero to
the left of the MPP and less than zero to the right. Appropriate
equations lead to the MPP condition in terms of PV module
voltage V and current I, i.e.,

dI I
=− .
dV V
Therefore, enough information is gathered to determine the
relative location of the MPP by measuring only the incremen-
tal and instantaneous module conductances dI/dV and I/V ,
respectively. Herein lies a primary advantage of this method
over the P&O algorithm. Incremental conductance can actually
calculate the direction in which to perturb the operating point Fig. 7. Simulated efficiency of the intelligent PV module with synchronous
to reach the MPP. Thus, under rapidly changing conditions, it rectifier.
should not track in the wrong direction, as P&O can.
Another advantage of this MPPT algorithm is that it should In spite of all these considerations, this first prototype has
not oscillate around the MPP once it reaches MPP since it not reached the proposed efficiencies over 95% yet, as shown
can determine when it has actually reached MPP. However, in Fig. 6. In any case, higher efficiencies can be achieved with
the maximum power condition is only rarely achieved since it a synchronous rectifier, which is currently under development.
is very difficult to adjust V to the exact VMPP when using a Simulations have been carried out on the synchronous rec-
constant adjustment step width. tifier, and the results (Fig. 7) show efficiencies in the range of
A solution to this problem would be to add a small marginal 95%–97%, with a maximum value of 98%. Thus, an efficiency
error e to the maximum power condition such that the MPP is increment of 2%–3% has been achieved in simulations, which
assumed to be found if would surely lead to the excellent behavior of the intelligent PV
modules.




dI I

Another important point of view is that related to the eco-



dV + V
≤ e. nomic aspects of the proposed prototype. In this sense, one of
the most challenging objectives of this development has been
The value of e must be determined experimentally with con- the reduction of its cost. As can be observed in Table I, the
sideration of the tradeoff between the problem of not operating price for the electronics scarcely exceeds 50 euros.
exactly at the MPP and the possibility of oscillating around it. At first sight, it seems to be an excessively high price.
It will also depend on the chosen perturbation step width and However, the cost of this distributed solution (0.53 euro/Wp) is
the resolution of the current and voltage measurements. below the final target of 1 euro/Wp, established for the elements
1070 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 53, NO. 4, AUGUST 2006

TABLE I
BUDGET OF A 100-W DC–DC CONVERTER

of the balance of systems (BOS; electronic components of a PV

system), and it could be even more attractive in time. Some con-
siderations have to be taken into account. First, the cost of this
hardware can be lowered if it is standardized, integrated, and
packaged within the junction box of a PV panel. Second, the
advantages of greater reliability and efficiency would increase
the amount of energy delivered and, thus, the return payback
on the installation investment. Finally, better data gathering
and monitoring could displace additional hardware that might
otherwise be required. Fig. 8. PLC communications in intelligent module.

C. Power Line Communications (PLC) communication channel. A preliminary measurement has been
performed with the spectrum analyzer to find out the viability of
One of the most innovative aspects of intelligent PV modules the proposed method. Considering this analysis, the following
arises from the possibility of communications with a central conclusions can be obtained.
control unit. Each PV module incorporates an electronic circuit
• Switching frequencies (fsw ) appear in the harmonics of
that can report its operation point (input and output voltages and
100 and 260 kHz. The options for selection of the carrier
currents), the dc–dc point, and other parameters. All collected
frequency (fc ) should be centered around 150 kHz.
data provide an innovative control and maintenance system. On
• Maximum signal level is 65 dBµV.
that basis, PLC communications will be used to perform a full
• Minimum noise level is approximately 37 dBµV.
monitoring and to assist other tools in performing a predictive
maintenance of the PV plant. On the other hand, commercial component features have to
Communication protocol MODBUS-RTU follows the ar- be considered for FSK communications. The most important
chitecture of master–slave, half-duplex. The master (control features are those related to the injection level of the FSK
system) inquires and the desired slave (PV module) answers. signal (around 100 dBµV) and the minimum carrier-to-noise
Several possibilities have been considered about the physical (C/N) relation for proper reception (15 dB). Their combination
means. The first option was by means of a separate RS485 provides a good margin for the selection of fc , even if this fc
twisted pair cable bus. The main disadvantage is the great num- coincides with the fsw . In this case, 20 dB over the minimum
ber of PV modules, and hence the complexity of wiring, since C/N is achieved. If better selection is performed, up to 63 dB
each PV module has two additional wires for communications. will be obtained (48 dB > minimum C/N).
Another possibility has been the wireless communication An additional circuit has been necessary to adapt the dc–dc
through a selected frequency. In this case, viability of proposal converter modules to PLC. The circuit is described in Fig. 8. L1
was not clear, and economical reasons rejected its utilization. and C1 (output capacitor of the boost converter topology) avoid
Finally, the selected option has been PLC. This option offers the communication signal entering panel circuitry and prevent
the most integration: no additional wire or communication dc–dc harmonics interfering with the communication signal. C1
channel is needed. Frequency-shift-keyed (FSK) modulation acts as a short circuit for the communication frequency, and L1
has been selected since it implies good behavior against in- has been selected to provide a little impedance that allows the
terference, it allows baud rates of about 600–4800 b/s, and minimum voltage level to be read in the FSK transceiver, which
the cost of electronics components is relatively low. For the is placed at each dc–dc converter. The value of L1 follows
intelligent PV module, communication costs are expected to two main aspects, namely 1) the maximum current driven and
represent about 5–7 euros (10%–15% of electronics total cost; 2) the line impedance (impedance of the wiring: approximately
see Table I). 200 m). T1 and C2 act like a filter that performs like a short cir-
There are several problems to be considered, such as the cuit for the frequency range used for communications. Finally,
great number of solar panels or the average noise level of the T1 allows injection and extraction of communication signal.
ROMÁN et al.: INTELLIGENT PV MODULE FOR GRID-CONNECTED PV SYSTEMS 1071

contains the different components of the PV system as well as

by the set of all the necessary measurement instruments.
As it can be seen in Fig. 11, the mechanical support consists
of two identical structures. Each of them can hold two PV
panels by means of two independently abatable frames. This
characteristic makes it well suited to experiment with different
inclinations and orientations. A switching board provides a
wide set of variations in the interconnection of the four PV
modules.
Voltage, current, radiation, module, and environmental tem-
perature sensors are used to precisely monitor the operation of
the whole PV system components during experiments. Finally,
the data acquisition unit Agilent 34970 A easily allows the
recording and visualization of all this information.
Since it would be hard, if not impossible in terms of
cost, to operate under controllable conditions, an additional
Fig. 9. Power losses in PLC. (a) Series association. (b) Parallel association.
(c) Series-parallel association. tool is required to evaluate the obtained results independently
of the operational conditions. With this aim, ROBOTIKER-
Injection efficiency depends on the selection of capacitors, TECNALIA Research Centre has developed SIMSOLAR, a
inductances, and transformer, as well as on the number and PV system simulation program that allows the user to specify
impedance of dc–dc PV modules (load of the circuit). different operational conditions for each PV module. Thus, the
To guess if communications for a specific PV system experimental results can be evaluated by comparing them with
will be possible, a study about the losses introduced by the the theoretical forecasts.
association of several PV modules with dc–dc converter and The software used for the simulation program is the Matlab
PLC communications has been carried out (Fig. 9). The fol- package with its SIMULINK toolbox suitable for dynamic
lowing losses can be demonstrated: system simulation. As a result, the described PV system test
platform has served to verify the optimal performance of the
P = 20 · log(2/(n + 1)) for the series or parallel association of
intelligent PV module.
n PV modules;
The next step will be to test this device in a real scenario
P = 20 · log(2/(n + m)) for the parallel association of m
by integrating it in a 5-kW PV plant located on the facade of
strings of n PV modules for each one.
ROBOTIKER-TECNALIA Research Centre’s facilities.
For instance, PV systems with 15 dc–dc series connected
will introduce 17.5-dB losses, and the group of five strings of
E. Future Research Strategies
20 modules for each one (100 PV modules) leads to 22 dB.
Two kinds of tests have been performed to show the viability The next step in the research of intelligent PV modules is the
of the PLC proposed solution, which is described in Fig. 10. monitoring of modular PV plants. Data obtained from the main
The kit is composed of four PV modules with dc–dc converter parameters of each PV module will be stored in databases for
incorporated and two evaluation kits based on the ST7538 their later analysis and processing. The implementation of an
FSK transceiver. Several architectures have been proposed: intelligent failure detection system will allow users to enhance
four series, four parallel, and two series and two parallel. The PV plants maintenance operations in the base of provided data.
features for these FSK communications tests were as follows: These novel detection strategies will be applicable in great PV
carrier frequency fc = 132 kHz and baud rate = 2400 b/s. plants, such as BIPV, in which the number of modules makes it
Second tests were performed with dc–dc prototypes with almost impossible to detect exactly the failure situation.
FSK communications already included in their printed circuit Once an abnormal situation is detected, the control and moni-
boards (PCB) instead of using demonstration boards. Commu- toring system is intended to act in consequence. One interesting
nication parameters were selected by programming, following application could be the remote power control of intelligent PV
the previous guidelines. In this case, minimum receiving sensi- modules. If the control system detects an excess of power above
tivity is established in 1 mVrms . the maximum input power in the PV inverter, a command will
Both test setups have demonstrated that the transmission and be sent to the whole PV modules in the sense of reducing the
reception of the communication signal from the dc–dc converter amount of delivered power and fixing it to a percentage of their
is possible. maximum output power (e.g., 80%–90%).
Finally, a survey on the performance of modular PV sys-
tems has to be carried out regarding PV inverter and possible
D. PV System Test Platform
modifications of power architecture that arises from the use
After the realization of a prototype, it essential to analyze the of intelligent PV modules. Several tests have established that
device performance. The PV system test platform is a powerful two consecutive MPPT algorithms (PV inverter and dc–dc
tool especially designed to evaluate the intelligent PV module. converter) can lead to work in local MPP if a good sizing is
This platform is constituted by the mechanical support that not addressed.
1072 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 53, NO. 4, AUGUST 2006

Fig. 10. PLC test platform.

At present, intelligent PV module is a more efficient and

cheaper global term solution for BIPV systems, and it provides
a great level of independence from an architectonic point of
view. In this sense, it should be economically feasible. For
a 100- to 200-Wp module, the electronics will be around
0.25–0.5 euro/Wp, which is less than the long-term objective
of 1 euro/Wp for the BOS components.

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[1] K. Kurokawa, H. Sugiyama, and D. Uchida, “Sophisticated verification of
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[2] Analysis of Photovoltaic Systems, International Energy Agency-
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[3] C. P. M. Dunselman, T. C. J. van der Weiden, S. W. H. de Haan, F. ter Heide,
Fig. 11. PV system test platform. and R. J. C. van Zoligen, “Feasibility and development of PV modules with
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Solar Energy Conf., Amsterdam, The Netherlands, Apr. 1994, pp. 313–315.
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ROBOTIKER-TECNALIA Research Centre, within a strate- [5] N. A. Lícia, C. F. Braz, and R. S. Selenio, “Control integrated maximum
gic research program cofunded by the Basque Country gov- power point tracking methods,” in Proc. 16th Eur. Photovolt. Solar Energy
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[6] D. P. Hohm and M. E. Ropp, “Comparative study of maximum power point
carries out a research activity focused on the electronics applied tracking algorithms,” in Proc. Photovolt.: Res. Appl., Apr. 2003, pp. 47–62.
to PV modules as a measure to improve the PV systems [7] M. Jantsch, M. Real, H. Häberlin, C. Whitaker, K. Kurokawa, G. Blässer,
behavior and to reduce the losses in PV systems. P. Kremer, and C. Verhoeve, “Measurement of PV maximum power point
tracking performance,” in Proc. 14th EU-PVSEC, May 2001.
This paper has described an innovative concept of PV mod- [8] N. Toshihiko, S. Togashi, and N. Ryo, “Short-current pulse-based
ule: the intelligent PV module solution. It is based on the design maximum-power-point tracking method for multiple photovoltaic-and-
and development of a PV module-integrated microsystem. The converter module system,” IEEE Trans. Ind. Electron., vol. 49, no. 1,
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developed electronics consists of a dc–dc converter with MPPT [9] K. Kenyi, T. Ichiro, and S. Yoshio, “A Study of a two stage maximum power
control and other general functions, such as power condition- point tracking control of a photovoltaic system under partially shaded
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In the cases of undesired PV system performance (partial
shadows, mismatching), electrical losses are reduced and sys-
tem efficiency is enhanced, as the dc–dc converter allows each Eduardo Román was born in Barakaldo, Spain,
PV module to work in its MPP independently from the rest of in 1975. He received the B.Sc. degree in telecom-
munications engineering (speciality in radiocom-
the PV panels. munications) from the University of the Basque
Several MPPT algorithms and configurations for dc–dc con- Country, Bilbao, Spain, in 1999. He is currently
verters have been considered and simulated, which show the working toward the Ph.D. degree in the field of pho-
tovoltaics in the Faculty of Engineering, Electronics
best results for the incremental conductance MPPT method and and Telecommunications Department, University of
boost configuration for the dc–dc converter topology. Experi- the Basque Country.
mental results have shown a maximum efficiency of 95%. He is currently a Development Engineer with the
Energy Unit, ROBOTIKER-TECNALIA Research
The proposed system also allows the communication of Centre, Zamudio, Spain, working in the field of renewable energy sources. He
every PV module’s electrical parameters to a central control was a grant holder of the Semiconductors Group, Electronics and Telecommu-
unit. PLC has been proven to be a suitable solution and of- nications Department, University of the Basque Country, in collaboration with
several projects related to photovoltaic (PV) energy. Since 1999, he has taken
fers the possibility of carrying out a PV system predictive part in many PV-related projects. His other research areas are in the fields of
maintenance. electronics and power electronics.
ROMÁN et al.: INTELLIGENT PV MODULE FOR GRID-CONNECTED PV SYSTEMS 1073

Ricardo Alonso was born in Barakaldo, Spain, in Sabino Elorduizapatarietxe was born in Erandio,
1979. He received the B.Sc. degree in telecommu- Spain, in 1955. He received the B.Sc. degree from
nications engineering from the University of the the University of the Basque Country (UPV/EHU),
Basque Country, Bilbao, Spain, in 2002, where Bilbao, Spain, in 1984. He is currently working to-
he was collaborating within the Electronic Design ward the Ph.D. degree at the Faculty of Engineering,
Group. He is currently working toward the Ph.D. University of the Basque Country.
degree in the Faculty of Engineering, Electronics and He has experience with industrial electrical and
Telecommunications Department, University of the industrial electronics companies. Currently, he is a
Basque Country. Lecturer with the University of the Basque Country
Since 2003, he has been with the ROBOTIKER- (UPV/EHU). Since 1999, he has been a Senior Re-
TECNALIA Research Centre, Zamudio, Spain, search and Development Engineer, mainly in pho-
where he is currently a Development Engineer in the Energy Unit. His main tovoltaic systems, with the Energy Unit, ROBOTIKER-TECNALIA Research
research interests focus on renewable energy systems, including the develop- Centre, Zamudio, Spain.
ment of communication and power electronics.

Pedro Ibañez (A’99–M’04) was born in Bilbao,

Spain, in 1964. He received the M.Sc. and Ph.D.
degrees in electrical engineering from the University Damián Goitia was born in Ordizia, Spain, in 1958.
of the Basque Country, Bilbao, Spain, in 1988 and He received the B.E. degree in industrial engineer-
1991, respectively. ing from the University of Mondragon, Arrasate-
From 1988 to 1997, he was an Assistant Profes- Mondragon, Spain, in 1985.
sor of electronic technology with the Electronics He was with Fagor Automation, where he de-
and Telecommunications Department, University of signed machine-tool computer numerical controls,
the Basque Country. In 1997, he became an Asso- and with the Electronics Department, Labein Tech-
ciate Professor. Since 1992, he has been with the nology Centre. Since 2000, he has been with the
ROBOTIKER-TECNALIA Research Centre, Zamu- ROBOTIKER-TECNALIA Research Centre, Zamu-
dio, Spain, where he is currently the Technology Director of the Energy Unit. dio, Spain, where he is a Senior Research and De-
He has worked on many projects related to electronics systems, digital control velopment Engineer in the Energy Unit. He has been
systems, and power converters for energy applications. He has participated in charge of several projects, such as electronic voting systems and equipment
in more than 30 research projects supported by public institutions (including for efficiency improvement of large photovoltaic systems. His current research
the European Union) and private companies. He has authored or coauthored interests are in the development of control electronic circuits applied to bar
of more than 30 papers and conference communications in national and processing machinery for the construction industry and in monitoring systems
international forums. for renewable energy source test benches.