Solar PV Switchgear and Step-Up Substation RFQ Guide

Prepared by: JCON ELECUpdated: 2026-10-16

Short answer

Prepare a solar distribution RFQ from the inverter AC schedule and approved connection diagram. Confirm AC collection voltage, transformer and MV/RMU requirements, protection and the utility boundary. PV modules, DC combiners, inverters and grid approval are not automatically included in a switchgear quotation.

Prefabricated substation production at JCON ELEC

Define the AC path from inverter to connection point

Rooftop self-consumption and utility solar projects can require different electrical packages. Use the approved SLD to identify inverter AC feeders, collection boards, transformers and the utility connection boundary.

AC collection and distribution at the specified inverter output voltage.
Step-up transformer interfaces, RMU or MV feeder switchgear as required.
Auxiliary power, metering, protection and plant-control communication interfaces.

Supply scope and interfaces

Supply scope and interfaces
Package item	Information to confirm	Boundary to agree
Inverter AC collection	Inverter voltage/current, feeder grouping and cable terminations	Distinguish AC collection equipment from DC combiners and PV arrays
Transformer and RMU/MV	Connection voltage, transformer ratio, capacity and protection	Confirm whether transformer and MV equipment form one supplied package
Generation and grid interfaces	Inverter data, metering, protection and plant-control requirements	Assign modules/inverters, grid studies, settings and utility approval

Information to include in the RFQ

Plant configurationRooftop or ground-mounted, installed DC/AC capacity, connection voltage, SLD and point of connection.

Inverter scheduleMake, model, quantity, AC voltage/current, feeder grouping and cable terminations.

Transformer packagePower rating, ratio, impedance, vector group, losses, cooling and MV switching arrangement.

Grid and siteUtility protection/metering requirements, export limits, altitude, temperature, IP, corrosion and layout.

Review documentsDatasheets, GA, SLD, schematics, brand list, relevant test reports, packing, delivery and commissioning boundary.

Related distribution equipment

Ring Main Unit (RMU)

Compact incoming and transformer feeder units with specified protection and accessories.

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Prefabricated Substation

Coordinated MV, transformer and LV package boundaries for project review.

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Low Voltage Switchgear

Main distribution, outgoing feeders and auxiliary power configured to the SLD.

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How to compare supplier quotations

Voltage compatibilityVerify the AC collection board matches the inverter; confirm transformer ratio and MV voltage separately.

Package completenessState whether inverter, transformer, RMU, cabling and auxiliary supply are included or supplied by others.

Grid responsibilitiesIdentify who provides settings, plant controller interfaces and utility approval; do not infer approval from equipment ratings.

Delivered scopeCompare electrical ratings, drawings, routine tests, lifting, shipping, installation and site support.

Frequently asked questions

Is a PV DC combiner box the same as an AC collection panel?No. A DC combiner is on the array side; an AC collection panel handles inverter AC feeders. Their ratings, switching and protection requirements differ.

Does every PV project need a step-up substation?No. The package depends on the connection voltage, capacity and approved SLD. Some rooftop projects connect at LV, while others require transformer and MV equipment.

Are solar modules and inverters included?This guide addresses distribution equipment. Modules, inverters and their supply responsibilities must be explicitly listed in the quotation scope.

Sources and scope

This JCON ELEC procurement guide organizes equipment and interface questions for project review. JCON product pages describe available equipment families; external manufacturer material is technical background, not evidence of JCON authorization, certification or a complete plant offer. Final ratings, compliance and responsibilities require approved project documents and an agreed supply scope.

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