Planning surge protection correctly – SPD types 1, 2, and 3 compared
Surge protection devices (SPDs) protect your electrical devices and systems from voltage spikes. Since the revision of DIN VDE 0100-443 in 2016, surge protection has been mandatory in many cases. This guide explains the different types of SPDs, where they are used, and how they can be combined with PV systems.
Quick info SPD
- Since 2016, surge protection has been mandatory in new buildings (DIN VDE 0100-443).
- Three levels: Type 1 (rough protection), Type 2 (medium protection), Type 3 (fine protection)
- Secure PV systems on the DC and AC sides
What is overvoltage and where does it come from?
Overvoltages are short-term voltage peaks that significantly exceed the regular mains voltage (230V/400V). They can damage or destroy sensitive electronics.
lightning strike
Direct or indirect lightning strikes generate extremely high voltage spikes of up to several hundred thousand volts in the grid.
switching surges
Switching large consumers (motors, elevators, welding equipment) on and off generates transient overvoltages in the building network.
network disruptions
Faults in the supply network, short circuits, or switching operations by the network operator can cause overvoltages.
SPD types in comparison – Types 1, 2, and 3
| SPD guy | designation | installation location | Protection against |
|---|---|---|---|
| Typ 1 | Lightning current arrester (rough protection) | Main distribution / meter cabinet | Direct lightning strike, lightning partial currents |
| Typ 2 | Surge arrester (medium protection) | Sub-distribution / meter cabinet | Indirect lightning strike, switching surges |
| Typ 3 | Fine protection (device protection) | Power outlet / directly on the terminal device | Residual overvoltages, sensitive electronics |
Mandatory since 2016 – When is SPD required?
DIN VDE 0100-443
Since October 2016, the standard has required the installation of surge protection devices in almost all new buildings and in the case of significant extensions to existing installations. Risk analysis is no longer necessary—SPD is standard.
When exactly is SPD mandatory?
In new buildings as a matter of principle, and in extensions or modifications to existing facilities if the effects of overvoltage pose a risk to people, property, or data loss. In practice, this means almost always.
Surge protection for PV systems
Photovoltaic systems are particularly vulnerable to lightning strikes due to their exposed location. Comprehensive surge protection is doubly important here.
DC-side protection
SPD Type 2 (DC) in the generator connection box or directly at the inverter input. Protects modules and inverters from overvoltages on the DC side.
AC-side protection
SPD Type 1+2 (AC) in the main distribution board. Protects the house network and the inverter output from mains and lightning-related surges.
Practical tips for surge protection
1. Type 1+2 combination arrester saves space
Combined SPD devices (types 1+2 in one housing) save valuable space in the meter cabinet and simplify installation.
2. Always fuse PV systems on both the DC and AC sides.
AC-side protection alone is not enough! Modules and inverters also need a DC SPD to protect them from lightning strikes via the roof surface.
3. Check the SPD status indicator regularly
Most SPDs have a status indicator (green = OK, red = defective). The status should be checked after every thunderstorm—a triggered SPD no longer provides protection.
4. Coordinated cascade protection
For optimum protection: Type 1 in the main distribution board → Type 2 in the sub-distribution board → Type 3 on sensitive devices. The gradation limits overvoltages step by step.
Conclusion: Surge protection is mandatory and protects your investment.
Surge protection devices are relatively inexpensive, but can prevent damage costing thousands of dollars. Installation is mandatory in new buildings and is also strongly recommended in existing buildings.
Important: SPD devices must be installed by a qualified electrician and checked regularly to ensure they are working properly.