Ultimo aggiornamento: 17 luglio 2026 | Versione 1.1

In sintesi: la norma IEC 62548 in termini di ingegneria pratica

La norma IEC 62548 è un riferimento internazionale fondamentale per la progettazione di impianti fotovoltaici.

L'attuale pubblicazione principale è IEC 62548-1:2023, con l'Emendamento 1 pubblicato nel 2025.

In termini di ingegneria pratica, la norma IEC 62548 affronta i principali argomenti di progettazione degli impianti fotovoltaici, tra cui:

• Cablaggio dell'array CC
• Tensione massima di sistema
• Progettazione di stringhe in parallelo
• Protezione da sovracorrente
• Commutazione e sezionamento
• Disposizioni per la messa a terra
• Coordinamento dei dispositivi di protezione

Il principio più importante è semplice:

Un impianto fotovoltaico deve essere progettato per le sue massime condizioni elettriche e ambientali possibili, non solo per i suoi valori di funzionamento normali.

Gli ingegneri devono considerare la tensione a circuito aperto in condizioni di clima freddo, la corrente inversa dalle stringhe in parallelo, la capacità di commutazione in CC, le condizioni dei cavi e il coordinamento delle protezioni.

La norma IEC 62548 deve quindi essere considerata come un quadro di riferimento per la progettazione di impianti fotovoltaici piuttosto che come una lista di controllo di prodotto.

Questa guida illustra la norma in termini di ingegneria pratica.

Indice dei contenuti

1. Cos'è la norma IEC 62548?
2. Versione attuale della norma IEC 62548
3. Cosa copre la norma IEC 62548?
4. Tensione massima dell'impianto fotovoltaico
5. Stringhe fotovoltaiche e progettazione di impianti in parallelo
6. Protezione da sovracorrente e fusibili gPV
7. Progettazione dei cavi CC fotovoltaici
8. Commutazione e sezionamento CC
9. Messa a terra ed equipotenzialità
10. Protezione contro le sovratensioni e norma IEC 61643
11. Progettazione del quadro di parallelo fotovoltaico (Combiner Box)
12. Coordinamento dell'inverter
13. Ispezione e documentazione
14. Errori comuni di progettazione secondo la norma IEC 62548
15. Flusso di lavoro di progettazione pratica
16. Lista di controllo ingegneristica IEC 62548
17. Domande frequenti
18. Raccomandazioni ingegneristiche finali

1. Che cos'è la norma IEC 62548?

IEC 62548 è comunemente utilizzata quando si discute della progettazione elettrica e della sicurezza degli impianti fotovoltaici.

La pubblicazione attuale è intitolata:

IEC 62548-1: Impianti fotovoltaici (PV) – Parte 1: Requisiti di progettazione

La norma affronta i rischi di progettazione derivanti dalle caratteristiche specifiche dei sistemi fotovoltaici in corrente continua (DC).

Gli impianti fotovoltaici differiscono dai circuiti elettrici convenzionali perché possono:

• Generare tensione ogni volta che è disponibile una luce solare sufficiente
• Produrre una tensione a circuito aperto più elevata a basse temperature
• Includere stringhe multiple in parallelo
• Utilizzare lunghi percorsi di cavi CC in ambienti esterni
• Operare a 1000V o 1500V CC
• Rimanere sotto tensione dopo la disconnessione della CA

Queste caratteristiche influenzano la selezione di:

• Cavi
• fusibili gPV
• Interruttori CC
• Isolatori
• Dispositivi di protezione contro le sovratensioni
• Scatole combinatore
• Connessioni dell'inverter

La norma IEC 62548 fornisce un quadro a livello di sistema per affrontare queste problematiche.

Il suo valore non risiede semplicemente nell'identificazione di prodotti conformi.

Lo standard aiuta i progettisti a comprendere come l'intero impianto fotovoltaico debba essere progettato in modo coordinato Sistema di protezione elettrica per impianti fotovoltaici.

2. Versione attuale della norma IEC 62548

Molti articoli tecnici meno recenti fanno ancora riferimento a IEC 62548:2016.

Per l'attuale lavoro di ingegneria, la pubblicazione di riferimento è:

L'attuale pubblicazione consolidata è IEC 62548-1:2023+AMD1:2025.

Il termine generale IEC 62548 rimane ampiamente utilizzato nel settore e nelle ricerche online.

Tuttavia, la documentazione tecnica dovrebbe identificare l'edizione effettiva utilizzata per un progetto.

Ciò è particolarmente importante in:

• Capitolati d'appalto
• Documenti tecnici EPC
• Dichiarazioni di conformità
• Rapporti di progettazione
• Registri di ispezione

Gli ingegneri devono inoltre verificare se il progetto utilizza un'adozione nazionale o regionale dello standard IEC.

Una dichiarazione generica come:

Progettato secondo la norma IEC 62548

potrebbe essere meno precisa rispetto all'identificazione dell'edizione pertinente e dello standard adottato.

3. Cosa copre la norma IEC 62548?

La norma IEC 62548-1 si concentra principalmente sulla progettazione di impianti fotovoltaici.

Il suo campo di applicazione include argomenti principali come:

• Cablaggio dell'array CC
• Dispositivi di protezione elettrica
• Sezionamento
• Disposizioni per la messa a terra

In termini pratici di sistema, la norma segue l'impianto fotovoltaico fino all'apparecchiatura di conversione della potenza finale, solitamente l'inverter.

Non si deve presumere che copra ogni sottosistema in un progetto solare.

Ad esempio, l'accumulo di energia a batteria introduce problematiche separate come:

• Corrente di guasto della batteria
• Gestione della batteria
• Protezione del bus DC
• Propagazione termica

I requisiti più ampi dell'installazione fotovoltaica dovrebbero essere coordinati anche con IEC 60364-7-712:2025 e le norme elettriche nazionali applicabili.

Ciò porta a un importante principio ingegneristico:

Non ci si dovrebbe aspettare che una singola norma IEC definisca ogni requisito di protezione per un intero impianto solare.

La norma IEC 62548 si occupa principalmente del livello di progettazione dell'impianto fotovoltaico.

Altre norme forniscono requisiti più dettagliati per specifiche apparecchiature o funzioni di installazione.

4. Maximum PV Array Voltage

Maximum PV voltage is one of the first design parameters that should be established.

Do Not Design Only from MPPT Voltage

The normal MPPT operating voltage of an inverter is not the same as the maximum voltage that a PV array can produce.

The maximum design voltage depends on factors including:

• Module open-circuit voltage
• Number of modules in series
• Module temperature coefficient
• Minimum expected temperature

Cold weather is particularly important.

As module temperature decreases, open-circuit voltage generally increases.

A string that appears acceptable under standard test conditions may exceed a device voltage limit under cold operating conditions.

Check the Complete DC Circuit

The maximum voltage assessment affects:

• Moduli fotovoltaici
• Connettori
• DC cables
• fusibili gPV
• Portafusibili
• DOCUP
• Sezionatori DC
• Interruttori automatici
• Scatole combinatore
• Inverter inputs

A system described as “1500V DC” is not automatically suitable for 1500V operation simply because the inverter or SPD carries a 1500V rating.

Every relevant component in the DC path must be suitable for the calculated conditions.

The complete electrical path must be reviewed, not only the main equipment.

5. PV Strings and Parallel Array Design

Series-connected modules primarily influence voltage.

Parallel-connected strings significantly affect current and fault conditions.

Normal String Current Is Not Enough

The engineer should review module data including:

• Maximum power current
• Short-circuit current
• Tensione massima di sistema
• Manufacturer protection limitations

However, normal operating current does not fully describe the fault condition.

Reverse Current from Parallel Strings

Consider one PV string operating independently.

Its available current is limited by the electrical characteristics of that string.

Now consider multiple strings connected in parallel.

If one string develops a fault, healthy strings may contribute reverse current toward the damaged circuit.

The designer should assess whether this current could exceed the safe limits of:

• Moduli fotovoltaici
• Cavi di stringa
• Connettori
• Other connected components

This analysis directly affects the need for string overcurrent protection.

More parallel strings do not simply mean that a larger fuse should be installed.

The fault architecture must be evaluated.

6. Overcurrent Protection and gPV Fuses

Overcurrent protection is one of the most important areas of PV array design.

What Is a gPV Fuse?

A gPV fuse is designed for photovoltaic DC circuit protection.

PV fuse-links for string and array protection are specifically addressed by IEC 60269-6.

PV circuits can involve:

• High DC voltage
• Corrente di esercizio continua
• Reverse current from parallel strings
• High enclosure temperatures
• Outdoor thermal cycling

These operating conditions differ from many conventional AC applications.

Understanding the difference between a gPV fuse and a standard fuse is important because ordinary AC fuses should not automatically be used as substitutes in PV DC circuits.

Does Every PV String Need a Fuse?

No.

The need for string protection depends on factors such as:

• Numero di stringhe in parallelo
• Corrente inversa potenziale
• Module limitations
• Portata di corrente dei cavi
• Equipment withstand capability

The correct process is:

Analyze the fault condition first. Select the protective device second.

Key gPV Fuse Selection Parameters

A gPV fuse review should include:

Rated DC Voltage

The fuse and fuse holder must be suitable for the maximum relevant DC voltage.

Corrente nominale

The fuse should carry normal PV operating current without nuisance operation while still protecting the circuit during abnormal overcurrent.

Module Limitations

The module manufacturer’s protection limits should be checked.

Capacità di rottura

The device must be capable of interrupting the applicable fault current.

Installation Temperature

Fuse behavior can be influenced by actual enclosure temperature.

A combiner box in direct sunlight may operate at a much higher internal temperature than the outdoor ambient temperature.

Coordinamento della protezione

A fuse should not be selected independently from the protected circuit.

The protection relationship can be simplified as:

PV Source → Cable → Equipment Limit → Protective Device

The protective device should operate before an unacceptable current condition causes serious damage to the protected circuit.

This is why fuse selection is an engineering coordination problem rather than a simple current-rating comparison.

For common 1000V PV string applications, engineers can also review KUANGYA’s 10×38 gPV fuse link for solar systems.

7. PV DC Cable Design

PV cable design is directly related to protection.

A fuse or breaker cannot correct fundamentally incorrect conductor selection.

Current-Carrying Capacity

Cable sizing should consider:

• Design current
• Temperatura ambiente
• Cable grouping
• Metodo di installazione
• Temperatura dell'involucro
• Solar exposure

The design should reflect realistic installation conditions.

Tensione nominale

Cable insulation must be suitable for the maximum PV circuit voltage.

This becomes increasingly important in 1500V DC systems.

Cable Routing

PV cable routing should consider:

• Mechanical protection
• Sharp edges
• UV exposure
• Water accumulation
• Connector strain
• Maintenance access

Positive and negative conductors should also be routed in a way that avoids unnecessarily large loop areas.

Cable management is not only an installation-quality issue.

It influences long-term electrical reliability.

Connector Compatibility

PV connectors are a common failure point.

Physically mating connectors should not automatically be assumed to be electrically compatible.

Differences in:

• Contact materials
• Contact geometry
• Mechanical tolerances

may increase contact resistance.

This can lead to:

• Local heating
• Insulation damage
• Arcing
• Long-term failure

Connector selection and installation should therefore form part of the PV electrical design review.

8. Switching and DC Isolation

Safe isolation is a major requirement in PV array design.

Purpose of a DC Isolator

A DC isolator provides a means of separating part of the PV DC circuit.

It may support:

• Manutenzione
• Ispezione
• Inverter replacement
• Combiner box servicing
• Emergency procedures

The device must be suitable for the actual PV DC application.

A DC Isolator Is Not Automatically a Circuit Breaker

The two devices perform different functions.

A DC isolator primarily provides an isolation function.

An overcurrent protection device responds to abnormal current conditions.

A circuit breaker may provide switching and protective functions according to its design.

Engineers should select the device according to the required function rather than using the terms interchangeably.

Verify DC Switching Capability

PV DC switching is technically demanding because DC current does not have the natural periodic zero crossing found in AC systems.

The designer should verify:

• DC voltage rating
• Current rating
• Pole configuration
• Wiring arrangement
• Switching duty
• Idoneità ambientale

Some multi-pole DC devices require a specific connection arrangement to achieve their intended rating.

Requirements for switches, disconnectors and switch-disconnectors are addressed by IEC 60947-3.

Incorrect wiring may reduce interruption capability.

Isolation Must Be Practical

A disconnect shown on a single-line diagram may still be poorly positioned in the actual installation.

Engineers should ask:

• Is the isolator safely accessible?
• Is the isolated circuit clearly identified?
• Can maintenance personnel control reconnection?
• Does the arrangement support real maintenance work?

These factors should be evaluated together during Selezione del sezionatore CC, rather than checking voltage and current labels independently.

Safe isolation is both an electrical and operational design issue.

9. Earthing and Bonding

PV arrays may include extensive conductive structures such as:

• Module frames
• Mounting rails
• Electrical enclosures
• Cable management systems

The earthing and bonding strategy should be coordinated with:

• Electrical installation design
• Inverter requirements
• Lightning protection
• Applicable local regulations

Where protective bonding is required, the continuity of the bonding path should be maintained throughout the life of the installation.

Potential long-term problems include:

• Collegamenti allentati
• Corrosione
• Dissimilar metals
• Danno meccanico

Earthing Does Not Replace Surge Protection

A good earthing arrangement does not eliminate the need for correctly selected SPDs.

Similarly, an SPD does not correct a poor bonding system.

These functions interact but are not interchangeable.

10. Surge Protection and IEC 61643

PV arrays often include long outdoor conductors.

These conductors can be exposed to transient overvoltages caused by:

• Nearby lightning
• Direct lightning effects
• Electromagnetic coupling
• Switching events

IEC 62548 should be used together with more specific SPD standards where detailed surge protection design is required.

The IEC 61643 series includes:

• IEC 61643-31 for SPDs used on the DC side of PV installations
• IEC 61643-32 for PV SPD selection, installation and coordination

For a wider explanation of the standard family, SPD classifications and selection parameters, read our complete IEC 61643 surge protective device guide.

Key PV SPD Parameters

Important selection parameters may include:

• Tensione massima di funzionamento continuo
• Voltage protection level
• Corrente nominale di scarica
• Maximum discharge capability
• SPD type
• PV system topology

Selecting a product simply because it is described as a “solar SPD” is not sufficient.

Installation Location Matters

SPD performance depends partly on installation.

Long connection conductors can add additional voltage during a fast transient event.

Connection paths should therefore be kept appropriately short and direct.

Long cable distances between the PV array, combiner equipment and inverter may also require protection at more than one location.

Surge protection should be evaluated across the complete electrical path.

For 600V to 1500V photovoltaic applications, KUANGYA provides a Type 2 PV surge protective device for combiner boxes, inverter DC inputs and PV distribution cabinets.

11. PV Combiner Box Design

Il Scatola combinatore FV is a major coordination point in multi-string systems.

It may include:

• fusibili gPV
• Portafusibili
• SPD DC
• DC switching devices
• Barre di distribuzione (busbar)
• Terminali
• Apparecchiature di monitoraggio

The combiner box should reflect the overall PV array protection strategy.

String Input Design

Recensione:

• Number of incoming strings
• Corrente di stringa
• Reverse-current conditions
• Fuse requirements
• Cable entry
• Polarity identification

Output Circuit

The combined output may carry significantly more current than one individual string.

The designer should verify:

• Busbar rating
• Output cable rating
• Terminal rating
• Switching-device rating

Internal Temperature

Heat can be produced by:

• Fusibili
• Portafusibili
• Terminali
• Barre di distribuzione (busbar)
• Switching devices

Solar radiation can further increase enclosure temperature.

Component ratings and derating should reflect the actual internal operating environment.

IP Rating Is Not Enough

A high ingress-protection rating is important, but it does not prove that a combiner box has been correctly designed.

Electrical safety also depends on:

• Internal spacing
• Gestione termica
• Component coordination
• Passaggio dei cavi
• Connection quality

The complete assembly should be evaluated.

12. Inverter Coordination

L'efficacia solar inverter protection requires the PV array voltage, current and external protection architecture to coordinate with the inverter or other power conversion equipment.

Important inverter parameters may include:

• Maximum DC input voltage
• MPPT voltage range
• Maximum input current
• Maximum short-circuit current
• Number of MPPT channels
• Number of inputs
• Internal DC protection

Do Not Confuse MPPT Voltage with Maximum Input Voltage

The MPPT range describes the inverter’s normal operating range.

It is not the same as the maximum permissible DC input voltage.

Cold-weather open-circuit voltage must be checked separately.

Check Current Limits

Modern PV modules may have relatively high operating and short-circuit currents.

A string arrangement can be acceptable from a voltage perspective while exceeding the inverter’s current limitations.

Both voltage and current must be reviewed.

Verify Internal Protection

Some inverters include:

• SPD DC
• Interruttori CC
• Fuse functions
• Insulation monitoring

These functions should be checked against actual manufacturer documentation.

Do not assume every inverter provides the same internal protection architecture.

13. Inspection and Documentation

Documentation, commissioning tests and inspection for grid-connected PV systems are addressed more specifically by IEC 62446-1.

Correct design does not eliminate installation errors.

Documentation, commissioning and inspection are therefore essential.

Important system documentation may include:

• Single-line diagrams
• String configuration
• Module data
• Inverter data
• Protection-device ratings
• Cable information
• Isolation points
• Earthing arrangements

Documentation should match the installed system.

Commissioning Inspection

Inspection should look for:

• Polarità errata
• Collegamenti allentati
• Cavi danneggiati
• Incorrect protection ratings
• Incorrect switch wiring
• Poor cable support
• Water-entry risks

The objective is to verify both electrical design and installation quality.

Developing Failures

Many PV electrical failures develop gradually.

Gli esempi includono:

• Increasing connection resistance
• Terminal heating
• Connector deterioration
• SPD end-of-life
• Ingresso di acqua
• Corrosione

Preventive, corrective and performance-related maintenance practices are addressed by IEC 62446-2.

Periodic inspection can help identify problems before they become major failures.

14. Common IEC 62548 Design Mistakes

Mistake 1: Referring to IEC 62548 Without Checking the Edition

The project should identify the applicable publication and edition.

Mistake 2: Calculating Voltage Only from Normal Operating Conditions

Cold-weather open-circuit voltage must be evaluated.

Mistake 3: Assuming Every String Needs the Same Fuse Arrangement

String protection should reflect the actual fault architecture.

Mistake 4: Selecting a Fuse Only by Current Rating

Voltage, module limitations and installation conditions also matter.

Mistake 5: Using an AC Switch in a PV DC Circuit

The device must be suitable for the actual DC switching duty.

Mistake 6: Selecting Every Component Only by the Label “1500V”

Voltage rating alone does not define complete suitability.

Mistake 7: Ignoring Long Cable Routes

Cable length affects voltage drop, surge exposure and mechanical design.

Mistake 8: Assuming the Inverter Provides All Protection

Internal protection must be reviewed against the external array design.

Mistake 9: Choosing a Combiner Box Only by String Count

Current rating, thermal design and protection coordination also matter.

Mistake 10: Treating Compliance as a Product Certificate Exercise

Individually compliant components do not automatically create a correctly coordinated PV array.

15. Practical IEC 62548 Design Workflow

A practical PV array design workflow can be organized into eight steps.

Step 1: Collect Module Data

Record:

• Voc
• Isc
• Vmp
• Imp
• Temperature coefficients
• Tensione massima di sistema
• Relevant fuse limitations

Step 2: Define the Array Architecture

Determine:

• Modules per string
• Numero di stringhe in parallelo
• MPPT allocation

Step 3: Calculate Maximum Voltage

Consider project temperature conditions and module characteristics.

Check all relevant DC equipment.

Step 4: Evaluate Current and Fault Conditions

Recensione:

• Corrente di stringa
• Short-circuit current
• Parallel current contribution
• Inverter current limits

Step 5: Define Overcurrent Protection

Assess whether string protection is required.

Select appropriately rated gPV fuses or other protective devices.

Step 6: Design Cabling and Isolation

Recensione:

• Cable rating
• Current capacity
• Routing
• Caduta di tensione
• DC isolation points

Step 7: Assess Surge and Combiner Protection

Coordinate:

• PV SPDs
• Design della scatola combinatore
• Fuse protection
• Switching devices

Corretto DC fuse and DC SPD coordination is essential because overcurrent protection and transient overvoltage protection address different fault conditions.

Step 8: Verify the Complete DC Path

Recensione:

PV Module → String → Cable → Protection → Combiner → Isolation → Inverter

No component should be evaluated independently from the surrounding circuit.

16. IEC 62548 Engineering Checklist

PV Modules and Strings

• Module electrical data reviewed
• Modules per string confirmed
• Parallel string quantity confirmed
• Temperature coefficients checked
• Module protection limitations reviewed

Voltage Design

• Maximum open-circuit voltage calculated
• Minimum temperature considered
• Inverter maximum DC voltage verified
• All DC equipment voltage ratings checked

Current and Overcurrent Protection

• String current reviewed
• Short-circuit current reviewed
• Reverse current evaluated
• String fuse requirement assessed
• gPV fuse coordinated with the protected circuit

DC Cabling

• Cable voltage rating suitable
• Current capacity checked
• Installation temperature considered
• Cable routing reviewed
• Mechanical support reviewed

Switching and Isolation

• Isolation points identified
• DC voltage rating confirmed
• Current rating confirmed
• Pole configuration verified
• Device location supports maintenance

Protezione dalle sovratensioni

• Surge risk assessed
• PV SPD type reviewed
• SPD voltage characteristics coordinated
• Installation location checked
• Connection path reviewed

Scatola combinatore

• String input quantity correct
• Fuse ratings coordinated
• SPD suitable for the system
• Output current verified
• Thermal design considered
• Environmental protection suitable

Coordinamento dell'inverter

• Maximum DC voltage checked
• MPPT range checked
• Input current checked
• Short-circuit input limits checked
• Internal protection functions verified

17. Frequently Asked Questions

What is IEC 62548?

IEC 62548 is commonly used to refer to the international design requirements for photovoltaic arrays.

The current core publication is IEC 62548-1.

What is the current version of IEC 62548?

The current core edition is IEC 62548-1:2023, with Amendment 1 published in 2025.

The applicable edition and national adoption should be verified for each project.

Does IEC 62548 cover battery energy storage?

The main scope focuses on PV array design.

Battery energy storage requires additional standards and system-specific protection assessment.

Does every PV string need a fuse?

No.

The need for string overcurrent protection depends on parallel-string configuration, reverse current and the electrical limits of the circuit.

What is the difference between IEC 62548 and IEC 60364-7-712?

IEC 62548-1 focuses on PV array design.

IEC 60364-7-712 addresses electrical installation requirements associated with PV power supply installations.

They are related but not interchangeable.

Does IEC 62548 cover surge protection?

It addresses PV electrical protection at the array design level.

Detailed PV SPD requirements and selection principles are addressed more specifically by IEC 61643-31 and IEC 61643-32.

Can an AC isolator be used in a PV DC circuit?

Only if the device is specifically suitable and rated for the actual DC voltage, current and switching duty.

An AC rating alone does not demonstrate suitability for PV DC use.

Is IEC 62548 only for 1500V systems?

No.

Its design principles apply to PV array design more broadly.

However, 1500V systems require particularly careful review of voltage ratings, insulation and DC switching.

Is a compliant fuse enough to make a combiner box compliant?

No.

The complete assembly must be reviewed for:

• Component ratings
• Thermal conditions
• Cablaggio interno
• Environmental protection
• Coordinamento della protezione

18. Final Engineering Recommendations

IEC 62548 should not be treated as a list of protection devices that must be installed in every photovoltaic system.

Its real engineering value is in system-level design.

Start with the PV module.

Define the string configuration.

Calculate the maximum voltage.

Evaluate current and reverse-current conditions.

Then coordinate:

• DC cables
• fusibili gPV
• Dispositivi di protezione contro le sovratensioni
• Sezionatori DC
• Scatole combinatore
• Inverter inputs

Every protection device should address a specific electrical risk.

A gPV fuse should be selected because an overcurrent condition has been identified.

An SPD should be selected because surge risk has been evaluated.

A DC isolator should provide a clearly defined isolation function.

A combiner box should integrate multiple circuits without creating thermal or coordination problems.

The central engineering lesson is:

PV array safety depends on coordinated electrical design, not on selecting protective devices independently.

For modern photovoltaic systems, the complete DC path should always be reviewed:

PV Module → PV String → DC Cable → Overcurrent Protection → Combiner Box → Surge Protection → Isolation → Inverter

That is the practical purpose of IEC 62548.