Solar DC circuit breaker procurement: compare the evidence before ordering

Start with the circuit and the exact part number

A useful request for quotation identifies where the breaker belongs: a PV string, a battery circuit or a DC load circuit. Give the supplier the approved design requirements for that location. A description such as "solar breaker" leaves too much room for substitution.

A PV string is a series-connected group of photovoltaic modules. A battery circuit introduces a different source of electrical energy, while a load circuit feeds the equipment. Record the circuit location on the RFQ so the supplier can point to documentation for the intended application.

Ask your designer to provide the maximum design DC voltage, required current rating, fault-current requirements and protection function. Include the drawing reference and revision. Procurement can collect and compare those inputs; determining their values belongs to the electrical design review.

Require the complete manufacturer part number, including any suffix. Then ask whether the quote covers the breaker alone, accessories or an assembled enclosure. Put substitutions in a separate line for approval rather than allowing a family name to stand in for an agreed part.

Keep the device description precise. A circuit breaker, switch-disconnector, fuse and fuse holder have different functions. If a seller proposes one in place of another, return the proposal to the designer with the manufacturer's supporting documents before treating it as an equivalent quotation.

Read the solar DC breaker ratings as a matched set

Compare the rated DC voltage, rated current and breaking capacity for the same part and configuration. An ampere rating describes one attribute; it does not establish the device's complete suitability for the circuit.

Breaking capacity concerns the fault current the device is rated to interrupt under its stated conditions. Where the manufacturer uses Icu, preserve that designation in your comparison sheet. Keep the voltage, test basis and configuration beside the value so a number copied from another rating row cannot slip into the purchase order.

For a named manufacturer example, ABB's S800PV-SP string-protection page gives a family envelope up to 125 A and 1500 V DC, with Icu of 5 kA. Those are ABB product-family statements. They are neither LinkSolar product specifications nor a recommendation for your circuit.

The exact-model distinction is visible in ABB's catalogue: S802PVSP25 lists 800 V DC with 5 kA, while S804PVSP20 lists 1500 V DC with 5 kA. A shared family name does not make the voltage rows interchangeable.

Build one row per proposed part. Leave a field unresolved when the supplier has not supplied its evidence; do not copy the best value from a neighbouring model.

Confirm DC breaker poles, polarity and the manufacturer diagram

The pole configuration and polarity instructions must match the proposed part. Request the manufacturer's terminal diagram with its document reference and revision. A catalogue photograph cannot establish how a device is approved for use.

ABB explicitly identifies its S800PV-SP family as polarity independent and able to disconnect all poles. That example shows why these properties belong in the comparison sheet. It does not establish the same properties for another manufacturer's breaker or an unverified replacement.

If a supplier says "non-polarized" or "bidirectional," ask for the exact document supporting that statement. Have the designer compare the diagram with the project drawing, including the designated circuit location. Procurement should retain that approval with the quote.

When a supplier provides an older distributor sheet alongside a newer manufacturer instruction, ask it to identify the document applicable to the supplied part. Record the answer and attach both revisions for the designer to review. Resolve the conflict before approving a sample; procurement should not choose the more convenient diagram.

If the documents refer to different variants, ask for a corrected set before sample approval. Record the discrepancy precisely, for example: "quotation suffix differs from diagram reference." This gives the supplier something concrete to resolve and prevents an email assurance from becoming the only evidence in the order file.

Compare enclosure, temperature and documentation

Separate the breaker specification from the specification for the assembled enclosure. Ask the supplier which items its quotation includes and which document supports each claim about the finished assembly.

Collect the permitted ambient temperature, any applicable derating information and installation conditions for the exact device. Give the enclosure designer the expected environment and mounting arrangement. Avoid accepting an operating-temperature range without checking the conditions attached to it.

For an outdoor assembly, request evidence for the enclosure, cable entries and fitted components. An enclosure label or a breaker rating alone does not document the completed assembly. Ask for the referenced assembly drawing and identify who is responsible for confirming suitability after components are fitted.

The same distinction helps when sourcing supporting hardware. Compare the relevant cable-entry items in the solar accessories collection against the enclosure drawing; each selected item needs its own documented fit. Keep the enclosure and breaker acceptance decisions in the project file.

If the project requires compliance documents, give the supplier the exact requirement agreed by the responsible designer or project authority. Match any supplied document to the manufacturer, model and covered configuration. A logo on a listing is not a substitute for that check, and a document for a nearby model leaves the proposed part unresolved.

A solar circuit breaker quotation and sample checklist

Issue the purchase order only after the proposed part and its supporting records match the approved project requirements. Use the checklist below to make the supplier's response reviewable before commercial terms distract from unresolved technical fields.

1. Identify the item: manufacturer, full part number, suffix, quantity and supplied scope.
2. Attach the rating evidence: DC voltage, current and breaking-capacity references, including the datasheet revision for that item.
3. Attach the applicable diagram: pole configuration, polarity instructions and installation-document revision.
4. Record operating conditions: ambient limits, derating reference and enclosure or mounting assumptions.
5. Match the sample: photograph its label, record the sample identification and compare it with the approved documents.
6. Close discrepancies: retain the corrected supplier response and the designer's acceptance before order release.

Agree the sample acceptance plan before requesting samples. Identity checks and document review do not demonstrate fault-interruption performance. Specify who will perform any required testing and what evidence the project requires, rather than attempting an improvised fault test.

Keep commercial questions in the same RFQ: sample price, proposed minimum order, packaging, lead time and change notification. Ask the supplier to answer them explicitly. For later orders, require notice of a model or document revision before allowing it to replace the approved item.

Procurement questions and the next enquiry

Can I accept an AC breaker with the same ampere rating?

An AC rating alone does not establish suitability for a DC circuit. Request the exact model's DC rating and applicable configuration, then obtain the designer's approval.

Does a polarity-independent example cover every DC breaker?

No. The property must be documented for the proposed part. Keep its manufacturer's diagram with the order records.

What should I include in a sourcing enquiry?

Send the circuit location, approved requirements, preferred model or comparison candidates, drawings, quantity and destination. Use the project RFQ form to ask whether LinkSolar can support the sourcing request; confirm availability and commercial terms for the specific item in the reply.