Type 1+2 vs Type 2 DC SPDs: PV Array and Building Entry Selection

Quick Takeaway

Confirm the applicable solar DC duty before selection.
Record inspection and test evidence.
Keep acceptance documents with the equipment record.

Choosing between a Type 1+2 and Type 2 DC SPD is not just a matter of where the device is installed. For photovoltaic systems, the right decision depends on lightning exposure, external lightning protection, separation distance, cable routing, voltage rating, short-circuit withstand, and coordination with other SPDs.

For Sinobreaker DC SPD selection, the key question behind the primary keyword **type 1+2 vs type 2 dc spd** is simple: will the SPD need to discharge partial lightning current, or only limit induced and switching surge overvoltages?

Why DC SPD Selection Matters in PV Systems

Photovoltaic DC circuits can be long, exposed, and routed between outdoor arrays and indoor electrical equipment. This makes them vulnerable to transient overvoltages caused by nearby lightning, direct lightning effects, switching operations, and electromagnetic coupling.

IEC 61643-31 applies to SPDs intended for the DC side of photovoltaic installations rated up to 1,500 V DC, covering direct and indirect lightning effects as well as other transient overvoltages. IEC 61643-32 then provides selection, installation, and coordination principles for PV systems, including rooftop and ground-mounted arrangements.

That means a location label such as “array side,” “inverter side,” or “building entry” is useful, but it is not a complete selection rule. The project lightning-protection concept must be checked before specifying the DC SPD class.

What a Type 1+2 DC SPD Does

A Type 1+2 DC SPD is a combined lightning-current and surge arrester. It is intended to meet both Type 1 and Type 2 protection requirements.

In practical PV terms, this means a Type 1+2 DC SPD is considered when the device may need to handle lightning-current energy, such as when PV DC conductors enter a building protected by an external lightning protection system, or when separation distance from the lightning protection system is not maintained.

A Type 1+2 DC SPD is commonly selected where the installation concept indicates possible partial lightning current on the DC side. It must be matched to the PV system voltage, polarity arrangement, short-circuit conditions, and required protection level.

What a Type 2 DC SPD Does

A Type 2 DC SPD provides surge protection against transient overvoltages, especially those caused by induced lightning effects and switching events. It is not selected as the primary lightning-current arrester where direct or partial lightning current must be discharged.

In many PV systems without an external lightning protection system, and where direct lightning-current coupling is not expected, a Type 2 DC SPD may be suitable for protecting inverter DC inputs, combiner boxes, or array-side equipment from induced surges.

The final decision still depends on the project assessment. A Type 2 device must have the correct maximum continuous operating voltage, discharge current rating, voltage protection level, PV fault-current suitability, and coordination with upstream or downstream SPDs.

Type 1+2 vs Type 2 DC SPD: Core Difference

The practical difference is the level of surge duty expected from the SPD.

Phoenix Contact identifies a Type 1+2 device as a combined lightning-current and surge arrester fulfilling both Type 1 and Type 2 requirements, while a Type 2 device addresses the Type 2 surge-protection function. DEHN also treats Type 1 and Type 2 as different SPD classes in PV protection guidance.

Selection at the PV Array

At the PV array, the DC SPD is usually placed near string combiner boxes, array junction boxes, or inverter inputs depending on the system layout. The array location is often exposed, but exposure alone does not automatically mean Type 1+2 is required.

A Type 2 DC SPD is often considered where the PV array is not connected to an external lightning protection system, where separation distance is maintained, and where the design objective is protection from induced surges.

A Type 1+2 DC SPD should be considered where the array structure, mounting frame, cable route, or external lightning protection arrangement creates a credible path for partial lightning current. Rooftop PV systems especially require careful review because array frames, metallic structures, down conductors, and cable routes may change the surge duty at the SPD location.

Selection at the Building Entry

The building entry is a critical point because outdoor PV DC cables cross into the protected structure. If partial lightning current can enter with those conductors, the DC SPD at the entry point may need Type 1+2 capability.

For a building with an external lightning protection system, the designer must check whether the PV system maintains the required separation distance from the lightning protection system. If separation is not observed, lightning-current sharing may occur, and Type 1+2 protection is commonly required at the boundary.

If there is no external lightning protection system and no direct lightning-current path is expected, a Type 2 DC SPD may be appropriate at the inverter or building-entry position, provided it satisfies the system ratings and coordination requirements.

Why Location Alone Is Not Enough

IEC 61643-32 includes selection, installation, and coordination principles for SPDs in PV systems. It covers different arrangements, including rooftop and ground-mounted systems. This is why “install Type 2 at the array” or “install Type 1+2 at the building entry” is too simplified as a universal rule.

A correct Sinobreaker DC SPD selection should consider:

Whether the structure has an external lightning protection system.
Whether separation distance is maintained between PV conductors and lightning protection parts.
Whether PV DC cables enter the building from an exposed zone.
Whether the SPD is at the array, combiner, inverter, or building entry.
Whether upstream and downstream SPDs are coordinated.
Whether the selected SPD matches the PV system voltage and fault conditions.

Key Electrical Ratings to Check

A Type 1+2 or Type 2 label is only one part of the specification. The DC SPD must also match the actual PV system.

Maximum Continuous Operating Voltage

For PV DC SPDs, the maximum continuous operating voltage must be suitable for the maximum open-circuit voltage of the PV array under cold conditions. For systems up to 1,500 V DC, the selected SPD must be rated accordingly.

The SPD voltage rating should not be chosen only from the inverter nominal DC voltage. It should account for string design, temperature correction, maximum open-circuit voltage, and applicable safety margin.

Discharge Current and Impulse Current

For Type 1+2 DC SPDs, impulse current capability is a key rating because the device may need to discharge lightning-current energy. For Type 2 DC SPDs, nominal discharge current and maximum discharge current are central selection points.

The required value depends on the installation risk level, lightning protection concept, and project specification. Oversimplifying this step can lead to under-protection or unnecessary cost.

Spannung Schutzniveau

The voltage protection level indicates the residual voltage that protected equipment may see during a surge event. A lower protection level generally provides better limitation of transient overvoltage, but it must be evaluated together with system voltage, SPD class, discharge capability, and coordination.

The selected Sinobreaker DC SPD should provide a protection level compatible with the withstand voltage of the inverter, combiner equipment, monitoring devices, and other connected DC-side components.

PV Short-Circuit Suitability

PV DC circuits behave differently from AC circuits because DC arcs are harder to extinguish and PV generators can continue feeding fault current while illuminated. Therefore, the SPD must be suitable for the available PV short-circuit current and the system earthing arrangement.

When specifying a DC SPD, check the manufacturer documentation for PV use, disconnector behavior, backup protection requirements, and compatibility with the expected fault current.

Coordination Between Array and Inverter SPDs

Large PV systems may use more than one DC SPD location. For example, one SPD may be installed at a combiner box near the array, while another is installed at the inverter or building entry.

Coordination ensures the SPDs operate together instead of interfering with each other. If cable lengths are significant, additional protection may be needed at both ends of the DC cable route. If devices are installed close together, the manufacturer’s coordination instructions should be followed.

Good coordination helps ensure that surge energy is managed progressively and that the voltage at protected equipment remains within an acceptable range.

Practical Selection Logic for Sinobreaker DC SPDs

Use the following logic as a project-check framework, not as a substitute for the standard or engineering design.

When Type 1+2 Is Usually Considered

A Sinobreaker Type 1+2 DC SPD is usually considered when:

The building or PV structure has an external lightning protection system.
Required separation distance between PV conductors and lightning protection parts is not maintained.
PV DC cables may carry partial lightning current into the building.
The SPD is installed at a lightning protection zone boundary with lightning-current risk.
The project specification requires combined lightning-current and surge protection.

When Type 2 Is Usually Considered

A Sinobreaker Type 2 DC SPD is usually considered when:

No external lightning protection system is present.
Separation distance is maintained where relevant.
The expected threat is induced surge voltage rather than partial lightning current.
The SPD protects inverter DC inputs, combiner boxes, or DC distribution equipment.
The system design does not require Type 1 lightning-current discharge capability at that point.

Documents to Review Before Final Selection

Before specifying the final DC SPD, review:

PV string voltage calculation and maximum open-circuit voltage.
External lightning protection design, if present.
Separation distance assessment.
Cable routing between array, combiner, inverter, and building entry.
Inverter and combiner box surge-withstand requirements.
SPD datasheet ratings, wiring diagram, and backup protection instructions.
Coordination requirements between multiple SPDs.

Common Mistakes to Avoid

The most common error is selecting an SPD class by location only. A rooftop array can require different SPD classes depending on the lightning protection concept, and a building-entry SPD can be Type 2 or Type 1+2 depending on whether lightning-current risk exists.

Another mistake is focusing only on Type 1+2 vs Type 2 while ignoring voltage rating. A DC SPD with the wrong voltage rating is unsuitable even if the class appears correct.

It is also risky to ignore coordination. A strong SPD installed at one point does not automatically protect all equipment if cable lengths, installation layout, and downstream withstand levels are not considered.

FAQ

Is a Type 1+2 DC SPD always better than a Type 2 DC SPD?

No. A Type 1+2 DC SPD has combined lightning-current and surge-protection capability, but it is not automatically the correct choice for every PV location. If the project only requires Type 2 surge protection and no partial lightning-current discharge is expected, a correctly rated Type 2 DC SPD may be the appropriate selection.

Do I need Type 1+2 at the PV array or at the building entry?

It depends on the lightning protection concept, external lightning protection system, separation distance, and cable routing. Building entry points often need close review because outdoor DC cables enter the structure there, but IEC-based selection is not determined by the location name alone.

What rating should I check first for a Sinobreaker DC SPD?

Start with the PV system voltage and confirm the SPD is suitable for the maximum DC voltage of the array. Then check SPD class, discharge or impulse-current rating, voltage protection level, PV short-circuit suitability, wiring configuration, and coordination with other SPDs.

Related Sinobreaker Resources

Standards Reference

Applicable authority source