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Comment choisir un coffret de jonction photovoltaïque : 8 facteurs critiques avant l'achat
Le choix d'un coffret de jonction photovoltaïque est une décision importante lors de la conception ou de l'achat d'équipement pour un système photovoltaïque. Le bon coffret de jonction permet d'assurer une protection électrique adéquate, des connexions de chaînes fiables et une compatibilité avec l'onduleur et l'installation solaire globale.
Pour les installateurs solaires, les entrepreneurs EPC, les distributeurs et les équipes d'approvisionnement de projets, la sélection d'un coffret de jonction implique bien plus que le simple comptage du nombre de chaînes PV ou le choix entre des modèles 1000V et 1500V DC.
Vous devez prendre en compte la configuration de l'onduleur, la tension continue maximale, le courant de chaîne, la protection par fusible, la protection contre les surtensions, l'isolation DC, les exigences relatives au boîtier et les fonctions de surveillance.
Ce guide explique comment choisir un coffret de jonction photovoltaïque en examinant 8 facteurs critiques, vous aidant à évaluer les spécifications techniques, à communiquer avec les fabricants et à préparer une demande de devis plus précise.
Si vous débutez avec les coffrets de jonction PV, vous pouvez également lire notre guide complet sur les coffrets de jonction PV pour comprendre leur structure, leurs composants et leurs principes de fonctionnement.
Comment choisir un coffret de jonction photovoltaïque : en avez-vous réellement besoin ?
Avant de sélectionner un modèle, déterminez si votre système photovoltaïque nécessite un coffret de jonction séparé.
Un coffret de jonction photovoltaïque collecte plusieurs circuits CC provenant des chaînes photovoltaïques et les combine en un ou plusieurs circuits de sortie avant qu'ils n'atteignent l'onduleur ou tout autre équipement en aval.
Cependant, toutes les installations solaires ne nécessitent pas un coffret de jonction externe.
Considérez les situations suivantes :
| Configuration du système photovoltaïque | Un coffret de jonction est-il nécessaire ? | Considération principale |
|---|---|---|
| Chaîne PV unique | Souvent inutile | Vérifier la protection intégrée et les exigences d'entrée de l'onduleur |
| Deux chaînes indépendantes | Dépend de la conception de l'onduleur | Confirmer si les chaînes sont connectées à des entrées MPPT distinctes |
| Chaînes multiples en parallèle | Souvent approprié | Vérifier la protection contre les courants inverses et la capacité de sortie |
| Système photovoltaïque commercial en toiture | Souvent utile | Protection centralisée et gestion des câbles |
| Grand projet solaire au sol | Dépend de l'architecture du système | Collecte des chaînes, surveillance et exigences de maintenance |
La décision doit être basée sur l'architecture électrique plutôt que simplement sur le nombre de panneaux solaires installés.
Par exemple, si un onduleur fournit déjà suffisamment d'entrées indépendantes et les fonctions de protection requises, un coffret de jonction externe supplémentaire peut ne pas être nécessaire.
Cependant, lorsque plusieurs chaînes doivent être regroupées en un point commun, un coffret de jonction PV dédié peut simplifier le cheminement des câbles, la protection et la maintenance.
Point clé : Confirmez la configuration d'entrée CC de l'onduleur et le schéma unifilaire du projet avant de choisir un coffret de jonction.
2. Déterminer le nombre de chaînes PV et la configuration d'entrée/sortie
L'une des premières spécifications à confirmer est le nombre de chaînes PV devant être connectées.
Un coffret de jonction est généralement décrit par une configuration d'entrée/sortie, telle que :
- 2 entrées/1 sortie
- 4 entrées/1 sortie
- 6 entrées/1 sortie
- 8 entrées/1 sortie
- 16 entrées/1 sortie
Le premier chiffre représente le nombre de circuits de chaînes d'entrée, tandis que le second représente le nombre de circuits de sortie.
Par exemple, un coffret de jonction 6 entrées/1 sortie reçoit six circuits de chaînes PV et les combine en un seul circuit CC de sortie.
Une configuration 4 entrées/2 sorties, quant à elle, fournit deux circuits de sortie distincts.
Comment choisir la configuration appropriée
Avant de sélectionner le nombre d'entrées et de sorties, vérifiez :
- Combien de chaînes photovoltaïques sont incluses dans le projet ?
- How many MPPT inputs does the inverter have?
- Which strings are permitted to be connected in parallel?
- Does the project require one or multiple outgoing circuits?
- Is additional input capacity required for future expansion?
An important point is that the number of inputs does not automatically determine the number of strings that can safely be connected together.
Different MPPT groups, module configurations, and inverter input limits must be considered.
For larger installations, a customized combiner box may be required.
For example, KUANGYA has worked on a customized 16-string PV combiner box project integrating string protection, DC surge protection, and remote monitoring.
Read more about the actual configuration in our 16-String PV Combiner Box Project.
3. Select the Correct DC Voltage Rating: 600V, 1000V, or 1500V
The voltage rating is one of the most important specifications when purchasing a PV combiner box.
Common PV system voltage classes include:
| DC voltage class | Application typique | Selection considerations |
|---|---|---|
| 600V DC | Certain residential and smaller PV architectures | Verify actual maximum array voltage |
| 1000V DC | Systèmes photovoltaïques commerciaux et industriels | Check cold-temperature open-circuit voltage |
| 1500V DC | Large-scale and utility PV projects | Verify every component’s voltage rating and insulation requirements |
However, choosing a combiner box based only on the nominal system voltage is not sufficient.
Check the maximum open-circuit voltage (Voc)
The open-circuit voltage of a solar module increases as its temperature decreases.
Therefore, the maximum PV string voltage must be calculated using the module’s electrical specifications and the project’s minimum design temperature.
The calculation should consider:
- Nombre de modules connectés en série
- Tension en circuit ouvert du module (Voc)
- Voc temperature coefficient
- Lowest expected ambient or module design temperature
- Applicable PV system design requirements
The selected combiner box and all internal components must be suitable for the resulting maximum DC voltage.
Check every internal component
Do not verify only the enclosure’s voltage label.
The following components also need appropriate DC ratings:
- Liens vers les fusibles gPV
- Porte-fusibles
- DC SPD
- DC isolator or switch-disconnector
- Circuit breakers, where specified
- Barres omnibus
- Terminals and internal conductors
A 1000V DC enclosure does not automatically mean every installed component is suitable for a 1000V DC application.
For further information, refer to the official IEC 62548-1 photovoltaic array design requirements.
4. Verify the Current Rating and String Fuse Protection
Voltage is only one part of the selection process. Current capacity and overcurrent protection are equally important.
A properly specified combiner box must accommodate the operating current of the connected PV strings and the combined output circuit.
Understand the string current
The following information should be collected from the solar module datasheet:
- Le courant de court-circuit (Isc)
- Maximum power current (Imp)
- Maximum series fuse rating
- Module electrical configuration
The project engineer must then calculate the required design current according to the applicable standards and installation conditions.
Do not select fuse ratings using a universal multiplier without checking the actual module specifications and local design requirements.
Choose the correct gPV fuse
PV string protection commonly uses dedicated gPV fuse links.
When selecting a fuse, verify:
| Spécifications | Points à vérifier |
|---|---|
| Fuse category | Suitable gPV photovoltaic fuse |
| Tension nominale | Compatible with maximum PV DC voltage |
| Courant nominal | Coordinated with module and circuit requirements |
| Capacité de rupture | Suitable for the prospective fault current |
| Fuse holder | Compatible with the selected fuse and DC rating |
| Température | Consider actual operating and enclosure conditions |
The fuse link and holder must be evaluated as a compatible protection assembly.
An oversized fuse may fail to provide the intended protection, while an undersized fuse may cause unwanted operation.
For more information, see the official IEC 60269-6 photovoltaic fuse standard.
You can also explore KUANGYA’s DC Fuse and Fuse Holder product range for photovoltaic protection applications.
5. Check the DC SPD and Surge Protection Configuration
Surge protection is another important consideration when purchasing a solar PV combiner box.
PV systems may be exposed to transient overvoltages caused by lightning activity and switching events.
A suitable DC Surge Protective Device (SPD) helps limit transient overvoltages and protect connected equipment.
However, not every project requires the same SPD configuration.
What should you check?
Before confirming the SPD specification, consider:
1. SPD type
Depending on the lightning protection design and installation conditions, the project may require Type 1, Type 2, or a combined Type 1+2 SPD.
2. Maximum continuous operating voltage (Ucpv)
The SPD’s operating voltage must be compatible with the maximum PV system voltage and grounding arrangement.
3. Discharge current
Check the required nominal discharge current (In), maximum discharge current (Imax), or impulse current (Iimp), as applicable.
4. Voltage protection level (Up)
The selected SPD must provide a suitable protection level for the equipment being protected.
5. Backup protection
Confirm the manufacturer’s requirements for backup overcurrent protection and short-circuit coordination.
6. Status indication
A visual status window helps maintenance personnel identify the operating condition of the SPD.
For projects requiring remote fault indication, an SPD with a remote signaling contact may also be considered.
For additional technical information, refer to IEC 61643-31: Requirements and test methods for SPDs for photovoltaic installations.
6. Select the Appropriate DC Isolator and Switching Arrangement
A PV combiner box may also incorporate a DC isolator or switch-disconnector to provide a means of disconnecting the DC circuit for maintenance and servicing.
However, isolation and overcurrent protection are not the same function.
A DC isolator is designed for the specified isolation and switching duty. It should not automatically be treated as a replacement for a properly selected fuse or circuit breaker.
Before purchasing, confirm:
- Tension nominale de fonctionnement
- Rated operational current
- DC switching capability
- Nombre de poteaux
- Switching arrangement
- Applicable utilization category
- Required isolation and locking functions
The selected device must be suitable for the actual DC circuit and installation conditions.
Also check whether the inverter or another downstream device already provides the required switching function. This helps avoid unnecessary duplication.
For projects with different electrical architectures, the isolator configuration should be confirmed before manufacturing.
7. Evaluate the Enclosure, IP Rating, and Installation Environment
The enclosure protects the internal electrical components from environmental exposure and mechanical damage.
Choosing the wrong enclosure can affect long-term reliability, especially in outdoor PV installations.
What IP rating should you choose?
Common enclosure protection levels include:
| Indice de protection IP | General protection description |
|---|---|
| IP54 | Limited dust protection and protection against water splashes |
| IP65 | Dust-tight and protected against water jets |
| IP66 | Dust-tight and protected against powerful water jets |
| IP67 | Dust-tight and protected against temporary immersion under specified test conditions |
The required rating depends on the actual installation environment and project specifications.
Par exemple :
Commercial rooftop installations
Consider direct sunlight, temperature changes, rain exposure, and cable-entry sealing.
Coastal installations
Pay attention to corrosion resistance, material selection, and the effects of salt exposure.
Industrial environments
Evaluate dust, moisture, vibration, chemical exposure, and maintenance accessibility.
Ground-mounted solar farms
Consider UV exposure, enclosure durability, mounting arrangements, and long-term outdoor operation.
Check more than the IP rating
When evaluating a supplier’s enclosure, also check:
- Matériau de l'enveloppe
- Résistance aux UV
- Résistance à la corrosion
- Cable glands and sealing
- Internal temperature conditions
- Structure de montage
- Available maintenance space
- Labeling and identification
Remember that the enclosure’s effective protection depends on the complete installed assembly, including cable glands, unused openings, seals, and installation workmanship.
8. Decide Whether You Need String Monitoring and Remote Control
For larger commercial and industrial PV projects, monitoring functions can provide additional visibility into system operation.
A conventional combiner box mainly provides electrical connection and protection functions.
An intelligent PV combiner box can integrate additional monitoring and communication components.
Common monitoring functions
| Monitoring function | Objectif |
|---|---|
| Surveillance du courant des chaînes | Identify abnormal current differences between strings |
| DC voltage monitoring | Monitor DC operating conditions |
| Fuse status monitoring | Provide fault indication |
| Surveillance de l'état des parafoudres (SPD) | Identify SPD failure conditions |
| Contrôle de la température | Monitor internal enclosure temperature |
| Remote alarm | Send fault signals to a monitoring system |
| Communication interface | Transfer operating data to an external controller |
Depending on the project, communication may use RS485 and protocols such as Modbus RTU.
However, not every PV project needs all these functions.
Before purchasing, confirm:
- Number of monitoring channels
- Parameters to be measured
- Communication protocol
- Auxiliary power requirements
- Remote alarm requirements
- Compatibility with the plant monitoring system
For projects involving many PV strings, remote monitoring can help maintenance teams identify abnormal operating conditions without inspecting every string individually.
You can see how these functions can be integrated into a customized solution in our 16-String PV Combiner Box Project.
How to Prepare a PV Combiner Box RFQ: Information to Send Your Supplier
After confirming the eight factors above, the next step is to prepare a clear Request for Quotation (RFQ).
Providing complete project information helps manufacturers evaluate the required configuration and prepare a more accurate quotation.
Here is a practical checklist you can use.
| Information | Details to provide |
|---|---|
| Application | Residential, commercial, industrial, or utility-scale PV |
| Tension du système | 600V, 1000V, 1500V DC, or project-specific |
| Nombre de chaînes | Total number of PV string inputs |
| Input/output configuration | 4-in/1-out, 8-in/1-out, 16-in/1-out, etc. |
| Courant de chaîne | Module Isc, Imp, and calculated design current |
| Fuse protection | Required fuse type, rating, and configuration |
| DOCUP | Type, Ucpv, In, Imax/Iimp, Up, and protection arrangement |
| DC isolation | Required isolator or switch-disconnector specifications |
| Enceinte | Material, IP rating, and installation environment |
| Contrôle | Required measurement and communication functions |
| Quantité | Estimated purchasing quantity |
| Destination market | Country and applicable project requirements |
| Documentation | Drawings, BOM, datasheets, certificates, and test records |
Example: A basic quotation request
Suppose you are purchasing a customized PV combiner box for a commercial solar project.
Your initial inquiry could include:
- System voltage: 1000V DC
- Configuration: 16 inputs / 1 output
- Application: Commercial solar PV system
- Protection: gPV fuse protection and DC SPD
- Switching: DC isolator
- Monitoring: Remote monitoring required
- Installation: Outdoor
- Quantity: To be confirmed
This information provides a starting point for the manufacturer to review the configuration.
However, it is not a complete engineering specification. The module datasheets, inverter input limits, current calculations, grounding arrangement, and project-specific protection requirements must also be checked before the design is approved.
Common Mistakes to Avoid When Purchasing a PV Combiner Box
Even when the basic specifications appear correct, several purchasing mistakes can create problems during installation.
Mistake 1: Selecting a model based only on voltage
A 1000V label does not guarantee that every internal component is correctly rated.
Mistake 2: Ignoring inverter MPPT configuration
Not all PV strings can be combined into one output. Check the inverter architecture first.
Mistake 3: Choosing fuses based only on current
Fuse selection requires coordination with module limits, conductor capacity, fault conditions, and the applicable design requirements.
Mistake 4: Assuming every outdoor project needs the same IP rating
Environmental conditions differ. Specify the enclosure based on the actual installation location.
Mistake 5: Requesting monitoring without defining its functions
Simply asking for an intelligent combiner box is not enough. Specify the channels, measured parameters, communication protocol, and remote alarm requirements.
Mistake 6: Confirming production before reviewing the drawings
Always review the wiring diagram, component list, terminal arrangement, and enclosure layout before mass production.
What to Check Before You Choose a Solar PV Combiner Box
Choosing a solar PV combiner box requires careful consideration of electrical ratings, protection devices, enclosure specifications, and monitoring requirements. Before placing an order, compare the manufacturer’s technical proposal with your project’s actual requirements to ensure that the selected configuration is suitable for your solar installation.
Frequently Asked Questions About Solar PV Combiner Box Selection
1. How many strings can a PV combiner box support?
The number of strings depends on the model and customized design. Common configurations include 2, 4, 6, 8, and 16 inputs.
The final selection must also consider inverter architecture, MPPT grouping, current capacity, and protection requirements.
2. Is a 1000V DC combiner box suitable for a 1500V DC solar system?
No. A 1000V-rated assembly should not be used in a 1500V DC application unless the complete assembly has been specifically designed and verified for the required voltage. All internal components must have suitable ratings.
3. Does every PV combiner box need a DC SPD?
The requirement depends on the project’s surge protection design, lightning risk assessment, installation arrangement, and applicable standards.
Where an SPD is required, its type, operating voltage, protection modes, and discharge ratings must be properly specified.
4. What is the difference between a standard and an intelligent PV combiner box?
A standard combiner box primarily provides string collection and electrical protection.
An intelligent combiner box can additionally integrate monitoring sensors, communication modules, remote alarms, and other monitoring functions.
5. Can a PV combiner box be customized?
Yes. Depending on the manufacturer’s capabilities, the input/output configuration, voltage class, protection devices, enclosure, monitoring functions, and labeling can be customized to meet project requirements.
6. What documents should I request from a PV combiner box manufacturer?
Depending on the project, request:
- Product datasheets
- General arrangement drawings
- Single-line diagrams
- Internal wiring diagrams
- Bill of materials (BOM)
- Component certificates and declarations
- Relevant assembly verification records
- Routine test records
Make sure the documentation corresponds to the actual model, component configuration, and ratings being supplied.
Looking for a Reliable PV Combiner Box Manufacturer?
Choosing the right solar PV combiner box is not simply about finding a product with the correct number of inputs.
It requires a complete evaluation of electrical ratings, protection coordination, enclosure requirements, inverter compatibility, and project-specific monitoring functions.
Au KUANGYA, we provide PV combiner box solutions for different solar applications, including commercial and industrial photovoltaic systems.
Our product and customization capabilities cover:
- Different PV string input/output configurations
- 600V and 1000V DC product configurations
- Protection par fusible gPV
- DC surge protection
- DC isolation and switching
- Customized enclosure and wiring arrangements
- Monitoring and remote control solutions
We can also discuss OEM/ODM requirements for distributors, panel builders, and project contractors.
Explore our PV Combiner Box product range to learn more about available configurations.
Need a quotation for your project?
Send us your system voltage, number of PV strings, input/output configuration, protection requirements, monitoring needs, and estimated quantity.
Our team can help review your requirements and discuss a suitable PV combiner box solution.
Site web : https://www.cnkuangya.com/
Contact: sales@cnkuangya.com
KUANGYA – Reliable DC Protection Solutions for Solar PV Systems.
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