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Inv_PLUS(-HV)_PV Sizing_rev.2012-05-03

1Power-One Italy S.p.a.

Via San Giorgio, 642 – 52028 Terranuova Bracciolini – Arezzo – ItalyWebsite: www.power-one.com

Power-One Aurora PLUS and PLUS-HV Series Inverters:guide to the sizing of photovoltaic generators with Aurora Designer and Power-

One String Tool

Author: Gianluca Marri Approver: Antonio Rossi Date: 2012/05/03

Purpose

Guide to the sizing of photovoltaic generators with the Aurora Power-One PVI-XXX.0 Inverter, using theoffline “Aurora Designer” configurator and the online “Power-One String Tool” configurator. Both sizingtools are available on the website: www.power-one.com.

Field of application

The models to which the document refers are the Aurora Power-One PVI-XXX.0 PLUS and PLUS-HV Seriesinverters, as set out in table 1.

PLUS Series(Inverters with 55kW modules)

PLUS Serieswith isolation transformers

(Inverters with 55kW modules)

PLUS-HV Series(Inverters with 67kW modules)

PVI-55.0-TL PVI-55.0 PVI-134.0-TL

PVI-110.0-TL PVI-110.0 PVI-200.0-TL

PVI-165.0-TL PVI-165.0 PVI-267.0-TL

PVI-220.0-TL PVI-220.0 PVI-334.0-TL

PVI-275.0-TL PVI-275.0 PVI-400.0-TL

PVI-330.0-TL PVI-330.0

Table 1: PVI-XXX.0 PLUS and PLUS-HV Series inverters: types




PVI-XXX.0 - PLUS, PLUS-HV: Operating range and output voltage

Power-One’s centralised inverters in the PLUS and PLUS-HV series have a modular structure and theirconverter modules have a single-stage topology. This means that the power converter itself handles allthe functions for power conversion, maximum power point tracking of the photovoltaic generator (MPPTalgorithm) and controlling the current supplied to the grid. This “single-stage transformerless” topologyenables high conversion efficiency levels and demonstrates direct proportionality between the gridvoltage at which the inverter works (AC side) and the minimum input voltage at which the inverter canconvert and output power to the grid. The relationship which ties the minimum input voltage to operatein MPPT and the grid voltage at which it is possible to transfer energy from the photovoltaic field, is thefollowing:

Fig.1: PVI-XXX.0 PLUS and PLUS-HV Series Inverters: Link between Vgrid and Vin

The conclusion is, therefore, that the minimum voltage to operate in MPPT and so to output power tothe grid depends on the AC working voltage of the converter module and that any (upwards) divergencein the grid voltage value from the nominal value (320V AC for 55kW modules which make up the modelsin the PLUS series, 380V AC for 67 kW modules which make up the models in the PLUS-HV series) leadsto a reduction in the operating interval in MPPT with the module at full power.

The figure below sets out the conduct of the converter module as the grid voltage changes.

201,032Vgridmpp(min)Vin,




Fig.2: Voltage range for operations in MPPT as the grid voltage changes

Once the sizing of the photovoltaic generator has been completed and the typical curve of thephotovoltaic generator established, the take-off point of the module may depend on the grid voltage atwhich the module works.

If the grid voltage on which the converter module works is equal to the nominal voltage (320V AC), thevoltage range for operation in MPPT extends up to 485V DC. In these conditions the module canintercept the maximum power point and so extract and convert the maximum power which thephotovoltaic generator makes available.

If the grid voltage at which the converter module works is higher than the nominal voltage (e.g. 330VAC), the voltage range for operation in MPPT falls and does not go below 500V DC. In these conditionsthe module cannot intercept the maximum power point and works at point (B), i.e. at the minimumvoltage which allows power transfer to the grid. In these conditions, the maximum power which the

generator makes available is not extracted: the unextracted power is equal to P indicated in figure.

The grid connection voltage is therefore very important, since it determines the minimum voltage tooperate in MPPT of the converter module. It is necessary to take account of this aspect of the moduleduring the configuration of the photovoltaic generator: a configuration close to the minimum value tooperate in MPPT in nominal conditions could lead to a reduction in production for the mechanismdescribed due to the increase in the grid voltage on the output terminals of the converter module.




Note: As for the PLUS series, when ordering it is possible to choose, in the customisation module, anoutput voltage for converter modules at 300 or 320 V AC: this enables the voltage range to operate inMPPT to be expanded up to 455V DC and so to obtain a better configuration margin.

PLUS Series PLUS-HV Series

Module power 55 kW 55 kW 67 kW

Maximum input voltage 1000V DC 1000V DC 1000V DC

Minimum input voltageto operate in MPPT

465V DC 485V DC 570V DC

Output voltage converter modules 3F / / 300V AC 3F / / 320V AC 3F / / 380V AC

Maximum efficiency converter module 97.5% 98% 97.7%

Accessibility Total frontal Total frontal Total frontalTable 2: PVI-XXX.0 inverters, general features PLUS and PLUS-HV

PVI-XXX.0: Possible configurations

The Aurora PVI-XXX.0 centralised inverters offer three input configuration possibilities in order to meetthe needs of constructing the photovoltaic field.

PLUS Series

A) MULTI-MASTER: the 55 kW modules which make up the inverter act as separate inverters andmanage photovoltaic generators independently from each other.The main advantage of the Multi-Master configuration lies in the configuration flexibility (eachmodule can be configured differently from the others) and in the high number of independentMPPTs which the inverter makes available.The disadvantage lies in the fact that, in the case of breakdown of one of the modules, the wholeproduction associated with the module is lost, due to the complete independence of theconverter modules.

Version withtransformer

Version withouttransformer

Number ofindependent MPPTs

in M-M configuration

AC nominal power ofeach of the available

MPPTs




PVI-55.0 PVI-55.0-TL 1 55kW

PVI-110.0 PVI-110.0-TL 2 55kW

PVI-165.0 PVI-165.0-TL 3 55kW

PVI-220.0 PVI-220.0-TL 4 55kW

PVI-275.0 PVI-275.0-TL 5 55kW

PVI-330.0 PVI-330.0-TL 6 55kW

B) MULTI-MASTER/SLAVE: the 55kW converter modules are connected in parallel in pairs, thusacting as separate 110kW inverters; the configuration is envisaged for machines of power over110kW.




in configurationM-M/S


MPPTs

PVI-165.0 PVI-165.0-TL 2 1x55kW + 1x110kW

PVI-220.0 PVI-220.0-TL 2 2x110kW

PVI-275.0 PVI-275.0-TL 3 1x55kW + 2x110kW

PVI-330.0 PVI-330.0-TL 3 3x110kW

C) MASTER/SLAVE: the 55kW converter modules are connected in parallel, thus acting as a singleinverter with total power equal to the sum of the powers of the modules which make up theinverter.The main advantage of the Master/Slave configuration resides in the presence of the parallelbetween the converter modules: this connection in parallel enables operational redundancy sothat, in the case of a breakdown of one of the converter modules, there is a reduction inproduction only in the case in which the power available from the photovoltaic generatorexceeds the conversion capacity of the modules which remain in service.The disadvantage resides in the reduced configuration flexibility of the photovoltaic generatorand in the need for external protection devices for the inverter (ref. inverter installationmanual).



Number ofindependent MPPTsin M/S configuration


MPPTs

PVI-110.0 PVI-110.0-TL 1 110kW




PVI-165.0 PVI-165.0-TL 1 165kW

PVI-220.0 PVI-220.0-TL 1 220kW

PVI-275.0 PVI-275.0-TL 1 275kW

PVI-330.0 PVI-330.0-TL 1 330kW

PLUS-HV Series

A) MULTI-MASTER: the 67 kW modules which make up the inverter act as separate inverters andmanage photovoltaic generators independently from each other.The main advantage of the Multi-Master configuration resides in the configuration flexibility(each module can be configured differently from the others) and in the high number ofindependent MPPTs which the inverter makes available.The disadvantage lies in the fact that, in the case of breakdown of one of the modules, the wholeproduction associated with the module is lost, due to the complete independence of theconverter modules.



in M-M configuration


MPPTs

PVI-134.0-TL 2 67kW

PVI-200.0-TL 3 67kW

PVI-267.0-TL 4 67kW

PVI-334.0-TL 5 67kW

PVI-400.0-TL 6 67kW

B) MULTI-MASTER/SLAVE: the 67kW converter modules are connected in parallel in pairs, thusacting as separate 134kW inverters; the configuration is envisaged for machines of power over134kW.



in configurationM-M/S


MPPTs

PVI-200.0-TL 2 1x67kW + 1x134kW

PVI-267.0-TL 2 2x134kW

PVI-334.0-TL 3 1x67kW + 2x134kW




PVI-400.0-TL 3 3x134kW

C) MASTER/SLAVE: the 67kW converter modules are connected in parallel, thus acting as a singleinverter with total power equal to the sum of the powers of the modules which make up theinverter.The main advantage of the Master/Slave configuration resides in the presence of the parallelbetween the converter modules: this connection in parallel enables operational redundancy sothat, in the case of a breakdown of one of the converter modules, there is a reduction inproduction only in the case in which the power available from the photovoltaic generatorexceeds the conversion capacity of the modules which remain in service.The disadvantage resides in the reduced configuration flexibility of the photovoltaic generatorand in the need for external protection devices of the inverter (ref. inverter installation manual).


Number ofindependent MPPTsin M/S configuration


MPPTs

PVI-134.0-TL 1 134kW

PVI-200.0-TL 1 200kW

PVI-267.0-TL 1 267kW

PVI-334.0-TL 1 334kW

PVI-400.0-TL 1 400kW




MULTI-MASTER MULTI-MASTER/SLAVE MASTER/SLAVE

Fig.3: PVI-330.0-TL/PVI-400.0-TL: possible configurations

Sizing of the photovoltaic generator to be connected to a PVI-XXX.0 inverter

In order to illustrate the procedure for sizing a photovoltaic plant with an Aurora Power-One PVI-XXX.0inverter, a photovoltaic plant is considered with the following design data as an example:

- no. 966 Sharp ND-F220A1 modules of 220 Wp, for total power of 212.52 kWp- Roof installation- Coeff. Panel derating 0.975 (losses on DC side of 2.5%)- Maximum ambient temperature of +40°C- Minimum ambient temperature of -10°C

Example of configuration with PVI-220.0-TL inverter in MULTI-MASTER mode

The MULTI-MASTER mode is based on the operational independence of the converter modules whichmake up the inverter.

The photovoltaic generators which make up the plant must be independent from each other and thenumber of MPPTs is equal to the number of converter modules which make up the inverter.

Thus, in the case in question, we have 4 independent MPPTs to be configured.




This mode is recommended when the photovoltaic generator is not standard in terms of installationconditions and so makes the divisions into several MPPTs necessary.

Considering the design data we can configure the four 55 kW modules.

By way of example, we will use 4 different configurations for each module, so as to set out some possiblesituations.

PVI-220.0-TL inverter , configuration 55 kW modules:

1st 55kW module => 21 panels for 12 strings (252 panels)

2nd 55kW module => 23 panels for 10 strings (230 panels)

3rd 55kW module => 20 panels for 11 strings (220 panels)

4th 55kW module => 22 panels for 12 strings (264 panels)

Total 966 installed modules

To check the configuration we use the offline configurator Aurora Designer.

AURORA DESIGNER: Use of the offline configurator

The Aurora Designer calculation sheet is a tool with which to size the photovoltaic generator to beassociated with the Aurora inverters.

The configuration is made on the “Input Sheet” by the following steps:

1. Language selection;2. Selection of the panel to be used. Should the panel concerned not be present in the calculation

sheet database it is possible :a. To input it through the “Add Module”, by typing in the requested data in the input fields:

i. Brand: panel brand;ii. Modul Typ: panel model;

iii. STC Power: nominal power in standard test conditions, expressed in W;iv. Umpp: voltage at the maximum power point in standard test conditions,

expressed in V;v. Uoc: open circuit voltage in standard test conditions, expressed in V;

vi. Impp: current at the maximum power point in standard test conditions,expressed in A;

vii. Isc: short circuit current in standard test conditions, expressed in A;viii. Max Syst. Voltage: maximum system voltage of the panel,

expressed in V;ix. Tco Isc: temperature coefficient of the short circuit current, expressed in mA/°K;




x. Tco Voc: temperature coefficient of the open circuit voltage, expressed in V/°K.

Brand EcoPower

Modul Typ EP 230 P60

STC Power 230 Wp

Umpp 30.72 V

Uoc 36.9 V

Impp 7.48 A

Isc 8.01 A

max. Sys.Voltage 1000 V

Tco Isc 4.005 mA/K

Tco Uoc -0.13284 V/K

3. If the aim is for this module to be a permanent part of the database of theconfigurator, send an email to Power-One support to request input of the panel in the databasehttp://it.power-one.com/renewable-energy/submit-your-inquiry

4. Selection of the inverter: select the inverter model for realisation of the plant.

5. Selection of type of panel mounting: the mounting of the panels impacts on the temperatureincrease of the cells compared to the ambient temperature. In the configurator it is possible toselect one of 3 types of mounting:

a. Mounting on solar tracker: in this case the configurator applies +25°C to the cellcompared to the maximum ambient temperature set;

b. Mounting on a structure: in this case the configurator applies +30°C on the maximumambient temperature set;

c. Mounting on roof: in this case the configurator applies +35°C on the maximum ambienttemperature set.




6. Set-up of the minimum and maximum temperatures: the ambient temperatures must be inputand not the minimum and maximum temperatures of the cells of the panels of the photovoltaicgenerator. The configurator will consider:

a. To calculate the level of the minimum ambient temperature, the value of minimumambient temperature set (in other words if a minimum ambient temperature of -10°C isinput, the configurator will calculate the string voltages considering a cell temperature of-10°C).

b. To calculate the level of the maximum ambient temperature, the value of the maximumambient temperature set plus the increase in temperature linked to the type ofmounting chosen (in other words if a maximum ambient temperature of 40°C is inputwith a roof mounting, the configurator will evaluate the parameters with a celltemperature of 40°C+35°C=75°C).

c. To calculate the level of Vmp,typ@25°C ambient temperature, the value of the ambienttemperature of 25°C plus the rise in temperature due to the type of mounting chosen (inother words if a roof mounting is chosen, the configurator will evaluate the parameterswith a cell temperature of 25°C+35°C=60°C).

7. Set-up of the derating coefficient of the panels

The Derating Coefficent of the Panels (DCP) is an estimate of the losses in the DC section of the plant.

This value represents the ratio between the power which is available for conversion at the inputterminals of the inverter and the nominal power installed.

In other words, it takes account of the losses of the DC circuit: we may speak of the efficiency of the DCcircuit, which must not be confused in any case with the efficiency of the PV panels.

The losses which occur in the DC section of the plant ensure that, under standard test conditions , thenominal power installed may not be wholly available for conversion at the input terminals of theinverter.

Among the losses in the DC circuit we may include:

a. Losses for conduction in connection cables;b. Losses for conduction in fuses, disconnecting switches and other protection devices that

may be present;




c. Losses linked to dirt which deposits on the panels;d. Losses for mismatching or losses linked to the imperfect parity among the electric

characteristics of the panels. Nominally, in fact, the panels are all equal to each otherand have the same electric characteristics. However, as revealed by flash tests, thepanels have (albeit minimal) differences in their electric values. Since the photovoltaicgenerator is a collection of panels that are collected in various ways in series/parallel, ifno sorting of the panels is made or no choice of the panels with which to build thevarious strings, it is possible to incur losses connected to these differences (in terms ofcurrent as regards panels in the same string and in terms of voltage between the variousstrings as regards strings in parallel).

8. Configuration of the photovoltaic generator: choice of the number of panels in series andtherefore of strings in parallel for each MPPT (in the case of configuration with independentchannels) or for the individual MPPT (in the case of configuration with parallel channels).

AURORA DESIGNER: Configuration of the individual 55 kW modules

In the section “Step 1 – Input General Data” we select the brand and the model of the panel planned forthe project. Let us select “PVI-55.0 (or 55kW module)”, type of mounting and maximum / minimumambient temperature.

Note: In the case of configuration of a PVI-XXX.0 Multi-Master inverter with more than 2 modules, withAurora Designer it is necessary to configure a 55/67 kW module each time.

Let us configure the 1st module and set a configuration with 21 panels for 12 strings, for a total of 252panels.




Fig.4: Configuration 1st 55kW module with Aurora Designer

In the section “Results – Configuration of the system” let us check the total photovoltaic power installedin the 55kW module (“Total PV Power STC”) and total input power to the inverter (“. Total DC InputPower”).

The second value is duly corrected on the basis of the value set for the “Coeff. of Panel derating”. In thecase of a coefficient equal to 1, “Total PV Power STC and “Total DC Input power” are the same.

On the basis of these values, the configurator returns an estimate of the output power to the Inverter(“Estimate of output power to Inverter”) and a percentage (“Total PV Power STC / Nom-Max AC Power toInverter”) given by the ratio between the power installed and the nominal-maximum power of theInverter.

(in the case of PVI-XXX.0 centralised inverters, the nominal power and maximum power valuescorrespond)

In the section “Results – Voltages and currents” we can check the correctness of our configuration on thebasis of the temperatures which we have set, on the basis of the inverter’s working range.

It can be noted that the configuration of the strings, chosen by us in the example, is indicated as optimal,this is because the voltage “Vmp,typ@25C Ambient Temperature” is equal to 556V DC, in other wordsaround the nominal input voltage of the inverter.




Let us pass on now to the 2nd module and set a configuration with 23 panels for 10 strings, for a total of230 panels.

Fig.5: 2nd Configuration 55kW module with Aurora Designer

In this case the configuration of the strings is not indicated as optimal, but if we check the section“Results – Voltages and currents” it is important to highlight that the configuration of the 2nd module is,nonetheless, correct and functional, since the voltage “Vmp,typ@25C Ambient Temperature” is equal to609V DC, broadly in the work range of the inverter.

The advantage of a higher DC voltage is that, on a constant installed power basis, of reducing thenumber of strings in parallel on the DC side, thus simplifying cabling, reducing distribution losses andoffering the possibility of monitoring the individual string .

Finally the voltage value “Voc,Max@-10C” (951V DC) verifies the chosen configuration, since it is lessthan 1000V.

For the 3rd module, we can set a configuration with 20 panels for 11 strings, for a total of 220 panels.




Fig.6: 3rd Configuration 55kW module with Aurora Designer

The configuration of the strings is indicated as optimal (Vmp,typ@25C Ambient Temperature = 529V DC).

In this specific case let us check, in the section “Results – Voltages and currents”, also the voltagevalue“Vmp,Min@40C” on the basis of the minimum work ranges of the inverter.

In this configuration, the voltage “Vmp,Min@40C” is 497V DC, higher than the “Minimum Voltage tooperate in MPPT” of the Inverter (485V DC).

Note: In the sizing stage of a PVI-XXX.0 inverter, it is advisable to maintain a margin of 15V DC betweenthe “Vmp,Min” and the “Minimum Voltage to operate in MPPT” of the Inverter, in order to prevent anyfall in performance in terms of Voltage of the PV generator.

Finally for the 4th module of the PVI-220.0-TL inverter, we can set a configuration with 22 panels for 12strings, for a total of 264 panels.




Fig.7: 4th Configuration 55kW module with Aurora Designer

The configuration of the strings is indicated as optimal (Vmp,typ@25C Ambient Temperature = 529V DC).

In the section “Results – Voltages and currents” the configurator in the value of installed PV power(58080 w) indicates “ too high? ”.

This is because we have chosen to install a PV power that is higher than the nominal power of theinverter, in fact the percentage (“Total PV Power STC / Nom-Max AC Power to Inverter”) is over 100%.

In addition, in the section “Results – Configuration of the system” under the heading “Estimate of outputpower to Inverter”, the configurator indicates “55000w -power limit reached” and the “Total Number ofPanels” is higher than the “Maximum Number of Panels/Inverter”.

It is important to highlight that the nominal power installed should not cause alarm, but only providesindication of a possible power limitation of the inverter.

In fact the inverter can work with limited power, but it is not cost effective because it entails a reductionin the plant’s energy production.




It is therefore necessary for this operation to be done at a design level, paying due consideration to thecondition of the PV generator.

Example of configuration with PVI-220.0-TL inverter in MULTI-MASTER /SLAVE mode

In this configuration the inverter acts as many separate 110 kW inverters and

the number of MPPTs is equal to the Framework number (pair of 55 kW modules).

This mode is a good compromise between the independence of the photovoltaic generator connected toeach pair of modules and coverage of production in the case of an individual breakdown of the module.

In MULTI-MASTER /SLAVE mode, the inverter under consideration has 2 independent MPPTs to beconfigured.

With the design data, we may imagine the following configuration:

PVI-220.0-TL inverter , 110kW framework configuration

1st 110kW framework => 21 panels for 23 strings (483 panels)

2nd 110kW framework => 21 panels for 23 strings (483 panels)


To check the configuration we can use the online configurator POWER-ONE STRING TOOL(http://stringtool.power-one.com/)

POWER-ONE STRING TOOL: Use of the online configurator

Step 1 – Location

Select language and installation location




Fig.8: Selection of location, temperatures and PV panels with Power-One String Tool

Notes on “View”

Standard: in the configuration matrices allowed for the photovoltaic generator no indications areprovided as to the soundness of the configuration

User Friendly: the configurator, through colour mapping, indicates the soundness of the configuration inregard to the characteristics of the inverter.

Step 2 – Temperatures

Select the type of mounting

Set the minimum ambient temperature (this is also used as a minimum cell temperature tocalculate the string voltages)

Set the maximum ambient temperature (the maximum cell temperature at which the stringvoltages are assessed is calculated by considering the type of mounting selected)




Step 3 – Selection of PV panels

Select the brand and model of the panel chosen to realise the plant(Possibility of changing the parameters of the panel should the desired panel not be present inthe data base)

Step 4 – Inverter selection

Select the model of Inverter

Fig.9: Selection of Inverter with Power-One String Tool

Step 5 – Results

The proposed tables contain all the possible configurations that are acceptable for the selectedinverter, within a load factor between 40% and 130%.

All the proposed configurations are compatible, choose the box with the desired configuration

In the case of PVI-xxx.0 inverters, three configurations are proposed:- Multi-Master- Multi-Master/Slave- Master/Slave

In the view “User Friendly” the cells are coloured and mapped as follows:

Orange cells: the configuration is admitted but there may be one (or more) of the following conditions:

Installed power lower than 70% of the Pdc,max of the inverter

Installed power higher than the Pdc,max of the inverter

Yellow cells: the configuration is admitted and the “typical” take-off point of the photovoltaic generator(Vmp@Tamb,media) is not around the nominal input voltage of the inverter (Vin,nom).

Green cells: the configuration is admitted and the “typical” take-off point of the photovoltaic generator(Vmp@Tamb,media) is around the nominal input voltage of the inverter (Vin,nom).




In the table “Multi-Master /Slave configuration” let us select then the configurations desired for the twoMPPTs.

Fig.10: Selection Multi-Master /Slave configuration with Power-One String Tool

Step 6 - Report

Once the configuration for the plant has been identified, it is possible to create the configurationreport in which the detailed results of the selected configuration are given.




Fig.11: Configuration report with Power-One String Tool

A consideration on the Use factor, in this configuration is 94.2 %.

A value close to 100% indicates a good sizing of the system, but it is worth highlighting that in no casemay the nominal power installed generate alarm, damage or warranty problems.

In fact, in certain situations it can be useful to have a slight oversizing of the system (also around 110-115%) to take account of the losses due to the derating of the DC system.




On the other hand, a system which is excessively oversized would not have damaging consequences forthe inverter but would lead it to work at limited power, i.e. not to transfer to the grid all the poweravailable on the panels and so make poor use of them.

Of course, it is possible to check a Multi-Master/Slave system also using the offline configurator AuroraDesigner.

Let us select “PVI-220.0” as the Inverter and “Independent” as the configuration for the MPPT channels.

Fig.12: Configuration of PVI-220.0 inverter Multi-Master/Slave with Aurora Designer




Example of configuration with PVI-220.0-TL inverter in MASTER/SLAVE mode

The MASTER/SLAVE mode is based on the parallel (DC side) of all the converter modules which make upthe inverter.

This configuration guarantees a high level of immunity against individual breakdowns thanks to theredistribution of the power among the modules making up the inverter, it is necessary, however, tomaintain the same number of panels per string and include a general external DC interrupter switch tocut off the whole field.

In MULTI-MASTER /SLAVE mode, the inverter considered has a single MPPT to be configured.

With the design data, we may imagine the following configuration:

PVI-220.0-TL inverter , Master/Slave configuration

=> 21 panels for 46 strings (966 panels)


To check the configuration let us use the online configurator POWER-ONE STRING TOOL.

We then repeat the previous steps up to Step 5 – Results and in the table “Master/Slave configuration”let us select the configuration desired for the MPPT1.




Fig.13: Selection Multi-Master configuration with Power-One String Tool

As for the power, the mode with an individual MPPT permits automatic redistribution of the poweramong the modules which make up the inverter.

This is the strength of this configuration, which is best used with large photovoltaic generators installedin standard conditions, where total cover of breakdowns is required.

Note: In the case of “grounded” photovoltaic generators the configuration MUST be Master/Slave; noother configurations are allowed.

The presence of the earth connection for all the generators entails the loss of the prerequisite for theMulti-Master and Multi-Master/Slave configurations, which require the photovoltaic generators to beindependent.




Of course, it is possible to check a Master/Slave system also using the offline configurator AuroraDesigner.

Let us select “PVI-220.0” as the Inverter and “Parallel ” as the configuration for the MPPT channels.

Fig.14: Configuration PVI-220.0 inverter Master/Slave with Aurora Designer

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