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See our products Solar Connectors
Connectors for the reliable connection of PV modules and strings.
Your One-stop shop: Components for PV systems from Bürklin
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See our products Photovoltaic Fuses
Fuses and protective components for the safe operation of PV systems.
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See our products Tools for PV Installation
Tools for the assembly, fabrication and professional installation of PV components.
PV Systems: The Basics
Photovoltaic systems convert sunlight directly into electrical energy via the photovoltaic effect. In solar cells, incident light generates a direct current (DC) voltage. However, a single solar cell produces only a low voltage. For this reason, multiple cells are connected to form a solar module. Several modules are then connected in series to form so-called strings.
In commercial and industrial systems, this can result in voltages of up to 1,500 V DC – placing high demands on all components used.
How Is a PV System Structured?
A PV system consists of several coordinated subsystems. The correct dimensioning and selection of each individual component is critical for the safety, performance, and service life of the overall system.
- Solar modules generate direct current (DC).
- Multiple modules are wired together into strings.
- The DC cables lead to a string combiner box (SCB), which combines and protects the strings.
- The inverter converts the direct current into grid-compliant alternating current (AC).
- The AC wiring connects the system to the meter cabinet and the grid.
Why Component Selection Is Critical
The service life of a PV system is 25–30 years. During this period, the components are exposed to extreme conditions: UV radiation, temperature fluctuations, moisture, and mechanical stress.
Inferior connections, undersized cables, or incompatible connectors lead to power losses, increased resistance, and in the worst case, fires. Choosing high-quality, standards-compliant components is therefore not optional – it is a necessity.
View Solar Cells and Solar PanelsDC Side: Connection and Wiring of PV Systems
The DC side is the electrical foundation of every PV system. Depending on the system design, voltages of up to 1,000 V or 1,500 V DC may occur. This places correspondingly high demands on cables, connection technology, and protective components. Faulty or undersized connections can cause arcing, hot spots, and, in extreme cases, fires.
Correctly Sizing Solar Cables and Cable Cross-Sections
Correct dimensioning of DC cables is one of the most important planning tasks. The DC wiring is one of the most safety- and yield-critical components of a photovoltaic system. Solar cables connect modules, strings, string combiner boxes, and inverters. They are permanently exposed to weather conditions, temperature fluctuations, and mechanical loads – while simultaneously carrying high DC voltages.
Cable Sizing
- Short-circuit current (ISC) as the design basis
- Permissible voltage drop: max. 1% recommended
- Ambient temperature & installation method (cable duct, overhead run, underground installation)
- Typical cross-sections: 4 mm², 6 mm², 10 mm²
- Cable material: copper or aluminium
Minimising Voltage Drop
- Select an adequate cable cross-section
- Keep cable runs short through optimal inverter positioning
- Symmetrical string design for even load distribution
- Professionally crimped connections using calibrated tools
- Regularly check contact resistance
MC4 Connectors: The Industry Standard
MC4-compatible solar connectors have established themselves as the industry standard. Systems from manufacturers such as Stäubli Electrical Connectors enable permanently safe connections in outdoor environments.
Important:
- Use only system-compatible components
- Do not mix connectors from different manufacturers
- Use appropriate solar connector tooling
- Fully engage the locking mechanism
- Carry out visual inspections at each maintenance interval
Order No.:
37F2146
Manufacturer:
Stäubli Electrical Connectors
Manufacturer SKU:
32.6058
Total Price: 27.20 € *
1 pcs.
27.2034 €
10 pcs.
25.2637 €
Order No.:
37F2114
Manufacturer:
Stäubli Electrical Connectors
Manufacturer SKU:
32.0716P0100
Total Price: 0.80 € *
1 pcs.
0.7973 €
10 pcs.
0.7259 €
50 pcs.
0.6902 €
100 pcs.
0.6426 €
1000 pcs.
0.5712 €
Order No.:
37F2123
Manufacturer:
Stäubli Electrical Connectors
Manufacturer SKU:
32.6020-20100
Total Price: 340.34 € *
1 pcs.
340.3400 €
5 pcs.
314.1600 €
Order No.:
37F2002
Manufacturer:
Stäubli Electrical Connectors
Manufacturer SKU:
32.0142P0001-UR
Total Price: 2.45 € *
1 pcs.
2.4514 €
10 pcs.
2.2134 €
50 pcs.
2.0944 €
100 pcs.
1.9873 €
1000 pcs.
1.7493 €
Order No.:
37F2003
Manufacturer:
Stäubli Electrical Connectors
Manufacturer SKU:
32.0143P0001-UR
Total Price: 1.84 € *
1 pcs.
1.8445 €
10 pcs.
1.6779 €
50 pcs.
1.5827 €
100 pcs.
1.4994 €
1000 pcs.
1.3209 €
String Combiner Boxes and DC Protection
String combiner boxes combine multiple strings and perform protection and monitoring functions. Specially designed photovoltaic fuses are used in this area, rated for high DC voltages.
DC protection measures include:
- String fusing
- DC disconnection points
- Surge protection
- Monitoring options
Inverter and AC Side
The inverter is the central link between the PV system and the power grid. In addition to converting DC into AC, it handles PV system control and monitoring functions.
Inverter Types
Depending on system size and requirements, different inverter types are used: string inverters for small to medium-sized systems, central inverters for large ground-mounted systems, or microinverters for module-level power electronics. The number of connectable strings depends on the device type and the number of MPP trackers.
What Cable Cross-Section Is Required for the AC Cable from the Inverter to the Meter Cabinet?
The determining factors for sizing include, among others:
- Rated output of the system
- Cable run length
- Network configuration
- Selectivity of the protection devices
- Requirements of the grid operator
Here too, the principle applies: the voltage drop should be kept as low as possible.
Does the AC Cable Require a Separate Overcurrent Protection Device?
As a rule, separate protection is required before feeding into the main distribution board. This includes:
- Cable protection (overcurrent protection)
- Residual current protection (RCD)
- Surge protection
- Grid and system protection where applicable
The AC-side protection is governed in particular by:
- DIN VDE 0100-712
- DIN VDE 0100-410/430
- Surge protection requirements per DIN VDE 0100-443/534
- Application rules VDE-AR-N 4105 and 4110
- The technical connection conditions of the respective grid operator
Meter Cabinet and Grid Connection
The meter cabinet for the PV system is the technical interface to the public grid.
Typical Components in the Meter Cabinet
- Feed-in meter: Measurement of exported energy
- SLS switch: Selective line protection switch
- Surge protection: Protection against overvoltage events
- Grid and system protection (NA protection)
- APZ field: General space for additional equipment
- NAR protection: May be required for systems > 25 kW
Protection Technology and Standards
The right protection technology is critical for the safe and long-term operation of a PV system – both on the DC and AC side. The relevant standards define clear requirements for personnel protection, cable protection and system protection.
Surge Protection (SPD)
Surge protection is important on both the DC and AC side – especially for buildings with an external lightning protection system.
Photovoltaic Fuses
PV fuses are specifically designed for high DC voltages and differ from conventional AC fuses. They protect strings against reverse currents and short-circuit events.
Grid and System Protection (NA Protection)
For smaller systems, NA protection is often integrated into the inverter. For higher feed-in capacities, an external protection device may be required – depending on grid operator requirements.
Maintenance, Testing and Measurement Equipment
Power losses in PV systems often develop gradually – caused by contact issues, insulation damage or faulty strings. Without regular monitoring and maintenance, such problems can go undetected for years and significantly reduce yield.
Key Tests at a Glance
AC-Side Tests
- Mains voltage and frequency at the feed-in point
- Protective conductor and loop impedance
- Functional testing of protective devices (RCD/MCB)
- Evaluate inverter yield data
- Verify compliance with feed-in limit values
Measurement Equipment for PV Systems
Tools and Cable Assembly
Poor crimp connections are one of the most common sources of error in PV installations. They lead to increased contact resistance, localised heat build-up, and, in the worst case, arcing and fires. Appropriate tools and matched accessories are therefore an essential part of system quality – both during initial installation and during service work.
Best Practices for Cable Assembly
- Use only manufacturer-approved crimping tools
- Maintain the exact insulation strip length specified by the manufacturer
- Check crimp connections visually and with a pull test
- Keep contact surfaces clean and free of grease
- Secure cables with UV-resistant cable ties and cable holders
Tools for PV Systems
Solutions from Our Manufacturers
We work with leading manufacturers specialising in high-quality components for photovoltaic applications. Each manufacturer brings specific expertise and certified products for different areas of PV installation.
Stäubli Electrical Connectors
MC4 connector systems for standards-compliant, long-lasting connection technology on the DC side.
Discover Manufacturer
HellermannTyton
UV-resistant solutions for structured cable management in outdoor environments.
Discover Manufacturer
LAPP
Cables for photovoltaic applications with high voltage and temperature resistance.
Discover Manufacturer
Fluke
Measurement technology for DC and AC testing and structured system monitoring.
Discover ManufacturerBürklin: Your Partner for Photovoltaic Applications
In PV systems, the interplay between connection, wiring, protection technology and measurement equipment determines reliability and efficiency. Our services support you from component selection through to long-term supply assurance – for both the DC and AC side.
Technical Consulting & Selection Support
We assist with the selection of suitable components covering connection, wiring and the protection of your PV system.
Clear Portfolio & Structured Product Search
From solar cables to photovoltaic fuses – all relevant components are available in one place and easy to find.
Fast Availability
Many products are available at short notice and ready for immediate use – for reliable installation and maintenance planning.
Further Information on Photovoltaics
Interested in specific questions relating to PV systems? Our Knowledge Hub offers in-depth technical articles on photovoltaics, energy efficiency and connection technology – providing a solid foundation for evaluating and implementing your PV projects.
Frequently Asked Questions about PV Systems
The cable cross-section depends on the current rating, cable run length, permissible voltage drop and ambient temperature. Many PV systems use 4 mm², 6 mm² or 10 mm² cables. However, the specific system design is decisive for avoiding power losses and thermal stress.
A low voltage drop is achieved through adequately sized conductors, short cable runs and high-quality terminations. Clean crimp connections and compatible connector systems are just as important as the correct conductor cross-section.
As a rule, separate routing is required or at least recommended. This increases safety and reduces potential interference between DC and AC conductors. The applicable standards and grid operator requirements are authoritative.
Typically, the meter cabinet includes a feed-in meter, an SLS switch, surge protection and components for grid and system protection. Depending on requirements, an APZ field or NAR space may also be necessary.
Whether external NA protection is required depends on system size and the technical connection conditions. For smaller systems, the protection is often integrated into the inverter; for higher feed-in capacities, a separate solution may be necessary.