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Solar Combiner Boxes Explained

Enclosures & Components

Solar PV Combiner Boxes Explained

A combiner box brings the DC strings from the array together in one enclosure, with the isolation and protection a PV installation needs on the DC side.

Quick answer

A combiner box gives one place to isolate and protect the DC side of a solar PV system: a DC isolator and DC-rated surge protection, in a weatherproof enclosure. It is not a substitute for protection on the AC side of the inverter.

Solar DC and AC protection: features and options

DC combiner: string count and enclosure

Choose one input/one output for one string path, or two inputs/two outputs for two separate string paths. A two-string box does not automatically parallel the strings: follow the connection diagram and inverter MPPT layout. Both metal and plastic IP65 versions are listed below.

The combiner brings DC isolation and DC surge protection into an enclosure. Its 1000V rating is a limit, not a recommended array voltage. Check cold-weather open-circuit voltage, string current and the exact model’s ratings. Do not assume string fuses are included: confirm supplied equipment and any required string overcurrent protection from the model datasheet.

AC solar consumer unit

The WME10-SOL1 is a separate AC-side assembly with a 20A bi-directional RCBO, 32A isolator and kWh meter. Bi-directional operation matters where power can flow from the inverter towards the supply. The RCBO provides circuit protection, the isolator provides manual disconnection, and the meter measures energy. This assembly does not replace DC string protection.

Rotary isolation: choose AC or DC explicitly

The rotary isolator range includes AC ratings from 20A to 125A and 1000V DC options at 32A and 40A. An AC isolator must not be substituted for a DC-rated PV isolator. Select voltage, current, utilisation category and pole wiring from the exact manufacturer diagram. An isolator is a switching device, not overload or residual-current protection.

Choose your exact variant

Expand a product to compare its available configurations. Each link opens that exact option; current price and availability are shown on the product page.

WCED Solar PV Combiner Boxes — 1000V DC — 4 options
WCED Solar PV Consumer Unit – 20A Bi-Directional RCBO, 32A Isolator & kWh Meter — 1 options
WCED 4 Pole Rotary Isolator Switches 20A-125A — 9 options

WCED orders are normally dispatched the same day for next-day delivery. Availability and checkout delivery options apply; contact us for a time-critical installation.

What is inside

Component Purpose Standard
DC isolator Isolates the string(s) from the inverter for maintenance and emergencies BS EN IEC 60947-3
DC SPD Protects against surges on the DC side BS EN 61643-31
Weatherproof enclosure Houses and protects the components outdoors Rated for the location

Some combiner boxes also include string fuses or other protection depending on the design, so check the specification against the system.

Why use one

A purpose-built combiner box means the DC isolator and DC surge protection arrive as a tested assembly in a suitable enclosure, rather than being assembled from separate parts. BS 7671 Section 712 covers solar PV installations and sets the requirements for DC isolation. See DC surge protection for solar for how the SPD works and why it must be DC-rated.

Do not forget the AC side

The inverter’s AC side needs its own protection and an AC Type 2 SPD. See surge protection for solar and heat pumps.

Shop DC combiner boxes and SPD modules

1000V DC combiner boxes and standalone DC SPD modules.

Combiner boxesDC SPD modules

Frequently asked questions

How many strings does a combiner box handle?

WCED offers one-string and two-string versions, each in metal or plastic IP65 enclosures. Select the input/output arrangement for your installation.

Do I need a combiner box for a single string?

Not necessarily, but you still need DC isolation and DC surge protection, and a combiner box provides both in one enclosure.

Can I mount a combiner box outdoors?

Choose a unit with an enclosure rating suited to the location, and install glands and seals correctly.

Surge ProtectionDC Surge Protection for Solar (1000V)Surge ProtectionSurge Protection for Solar and Heat PumpsEnclosures & ComponentsIP40 vs IP65 EnclosuresSurge ProtectionSPD kA Ratings Explained

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