What an SPD can and cannot address
| Condition | SPD role | Additional function to review |
|---|---|---|
| Lightning-induced or switching transient | Limit transient voltage and divert surge current within its rated application. | Lightning-risk assessment, bonding, coordinated SPDs and equipment withstand |
| Sustained overvoltage | Not a continuous voltage regulator. | Voltage monitoring, control and disconnection appropriate to the system |
| Undervoltage or brownout | Does not restore voltage. | Power-quality monitoring, source control or approved backup strategy |
| Power outage | Does not supply energy. | Storage/generator capacity, transfer equipment and operating-mode design |
| Repeated utility events | May be exposed to repeated stress but does not diagnose the network. | Event logging, utility investigation, maintenance and end-of-life inspection |
Map protection boundaries in every operating mode
A PV-plus-storage installation can have different power paths in normal grid operation, backup operation, maintenance isolation and shutdown. Draw each mode before deciding where surge protection is required.
- Identify the service entrance, main distribution board, backup board, inverter, battery interface and PV array boundaries.
- Separate AC and PV DC sections and identify the maximum continuous voltage at each point.
- Document the earthing and bonding arrangement and any external lightning-protection system.
- Trace cable routes, exposure and distance between protection stages.
- Coordinate upstream and downstream SPDs with equipment withstand and manufacturer rules.
- Keep connecting conductors short and routed as required by the SPD manufacturer and project design.
- Provide isolation, backup protection, status indication and safe replacement access where required.
- Verify protection in both grid-connected and backup operating modes.
SPD procurement checklist beyond kA
Electrical system
AC or PV DC, nominal and maximum continuous voltage, phase/pole arrangement, earthing system and prospective fault current.
Surge duty
Required SPD type/class, discharge-current parameters, impulse-current requirement where applicable and voltage protection level.
Protection coordination
Backup overcurrent protection, short-circuit behaviour, upstream/downstream coordination and protected-equipment withstand.
Installation
Lead length and routing, conductor size, enclosure, temperature, UV, dust, salinity, mounting and replacement access.
Maintenance
Status indication, remote signaling where needed, end-of-life behaviour, inspection frequency, spares and replacement method.
Evidence
Exact model datasheet, applicable test/certification documents, installation instructions and project approval requirements.
Do not rank products from one headline discharge-current value. A high nominal figure cannot compensate for incorrect voltage selection, AC/DC mismatch, poor coordination, long leads or an incompatible earthing arrangement.
Australia and UAE considerations
Australia
Confirm current wiring, PV-array, surge and equipment requirements with the applicable standards, network rules and licensed designer/installer. Lightning exposure, coastal corrosion and switchboard compatibility remain project-specific.
United Arab Emirates
For Dubai, use the current DEWA DRRG standards and connection/inspection resources. High temperature, UV, dust and salinity can affect enclosure, conductor routing, inspection and replacement planning.
Solar SPD FAQ
Will a whole-house SPD prevent damage during every grid event?
No. It addresses defined transient overvoltage conditions. Sustained voltage abnormalities, outages, frequency events and transfer problems require other protection or control functions.
Does every PV and battery system need the same SPD locations?
No. Locations depend on power paths, cable exposure, lightning protection, earthing, operating modes, equipment withstand and local requirements.
Which documents should be requested with an SPD quotation?
Request the exact model datasheet, application category, voltage and discharge ratings, protection level, short-circuit/backup-protection requirements, wiring instructions, environmental limits and applicable test or certification evidence.