Solar DC Distribution Board (DCDB) Manufacturer in Vadodara, India

A DC distribution board combines the DC output of several solar PV strings into one protected output to the inverter. Each incoming string gets its own DC fuse, the combined output gets an isolator so the array can be disconnected safely, and a surge protection device shunts the voltage spikes that direct and indirect lightning strikes put onto long DC runs. It is a small board doing a job that protects a very expensive inverter.

Wisdom Techno Solutions builds DCDBs at our Vadodara works for rooftop and ground-mounted plants. They are made in polycarbonate or metal-clad enclosures, dust-proof, vermin-proof and waterproof, in IP54 for indoor and IP65 for outdoor installation, with MC4 connectors and PG glands for plug-in and plug-out cabling. Standard configurations run from 1 in–1 out to 10 in–10 out.

• DC fuses per string — premium makes including Ferraz Mersen and Eaton
• DC MCB or DC isolator on the output, so the array can be isolated under load
• Surge protection device against direct and indirect lightning surges
• Reverse blocking diodes and organised DC termination points
• MC4 connectors and PG plastic glands — plug-in, plug-out cabling
• Built to IEC 61439-1 and MNRE guidelines; IP54 indoor, IP65 outdoor

Configurations from 1 in–1 out to 10 in–10 out, wall mounted, with the specifications below as the standard build.

The table below is the standard build. String count, fuse rating, isolator rating and SPD class are set from the array layout, the string voltage and the inverter's DC input window.

Three boards sit in the same solar plant and are frequently mixed up in enquiries, because two of them are on the DC side and look similar. They are at different points in the chain.

A DCDB earns its place as soon as more than one string feeds an inverter, and always where the DC cabling runs any distance. Two things justify it. First, per-string fusing: without it a fault in one string is fed by all the others, and the fault current has nowhere to clear. Second, surge protection: long DC runs on a roof or across a field are an efficient antenna for lightning-induced surges, and the inverter's DC input is what pays for their absence.

It is not needed where the inverter already provides what the board would. Many modern string inverters include integrated DC isolation and string fusing for a small number of strings, and on a small rooftop system with two short strings a separate DCDB can be genuine duplication. The way to settle it is to read the inverter's datasheet: how many DC inputs, is each fused, is there an integrated DC isolator, and what SPD class does the manufacturer require upstream.

One thing is not optional, whichever route is chosen: a safe DC isolation point. A PV array cannot be switched off — in daylight it is live, and DC arcs do not self-extinguish the way AC arcs do. Somebody has to be able to isolate the array safely before working on the inverter. If the inverter does not provide that, the DCDB must.

Send these and every offer you receive will be comparable:

• Array layout: number of strings, modules per string, and module model
• String voltage (Voc at the site's lowest expected temperature) and string current (Isc)
• Inverter model and its DC input arrangement — number of inputs, integrated fusing, integrated isolator
• Configuration required — 1 in–1 out through to 10 in–10 out
• Indoor or outdoor mounting, and therefore IP54 or IP65
• Enclosure preference — polycarbonate or metal-clad
• SPD class required, or the inverter manufacturer's requirement
• Whether reverse blocking diodes are required by the array configuration
• Cable size and connector type at both ends
• Any MNRE, developer or lender specification the board must comply with

The two numbers that matter most are the string open-circuit voltage at the lowest expected temperature and the short-circuit current. Both come off the module datasheet and both size the fuse, the isolator and the SPD.

• Using AC-rated devices on the DC side. A DC arc does not have a zero crossing to help it extinguish. AC fuses, AC MCBs and AC SPDs are not interchangeable with DC-rated ones, and substituting them is a fire risk rather than a saving.
• Sizing the string voltage at 25 °C. Module open-circuit voltage rises as temperature falls. The board and the inverter must be rated for Voc at the site's lowest expected temperature, not at the datasheet's test condition.
• Leaving the SPD out on a rooftop array. Long DC runs collect induced surges, and the inverter's DC input is the thing that fails. It is the cheapest component protecting the most expensive one.
• Assuming the array can be switched off. In daylight a PV array is live. Without a proper DC isolation point, work on the inverter means working on a live DC circuit.
• Choosing an IP65 board and mounting it in full sun with no thought to heat. A sealed enclosure in direct sunlight runs hot, and fuse ratings derate with temperature.
• Ordering by "4 in 4 out" alone. The configuration says nothing about string current, voltage or SPD class. Two boards with the same in-out count can be completely different inside.
• Omitting the fault level from the enquiry. Without it no vendor can size the assembly correctly, and the offers stop being comparable.
• Writing "as per IEC 61439" with no part and no year. The verification evidence a manufacturer submits has to be traceable to a specific standard and configuration.

Wisdom Techno Solutions builds and integrates this assembly at our works in Vadodara, Gujarat, for industrial, EPC and infrastructure projects across India. Every board is routine-verified in-house before dispatch, with the test records, approved drawings, bill of materials with makes as supplied and protection settings as applied issued with it. Customer, consultant and third-party witnessed testing are all supported.

Engineering guides from our team on the calculations and design decisions behind a DC distribution board:

• BESS electrical panel design — PCS, ACDB, DCDB, protection and grid interface
• Electrical panel earthing and earth busbar design
• Electrical load list and transformer / incomer sizing
• Circuit breaker selectivity, discrimination and cascading
• Electrical panel heat dissipation and cooling
• Icu vs Ics vs Icw — selecting the correct short-circuit rating
• Electrical panel FAT and routine test checklist
• How to prepare an LT panel technical specification and RFQ

If this is not the right fit for your layout, these are the alternatives we build to the same standard:

• AC distribution boards — the AC side of a solar plant, after the inverter
• Array junction boxes — the first DC collection point at the module array
• AC combiner boxes — combining multiple inverter outputs before the ACDB
• Solar ACDB and DCDB — the full AC and DC distribution set for a solar plant
• 800 V LT panels — 800 V distribution for solar and special applications
• PCC panels — power distribution from the transformer incomer to the plant's outgoing feeders

Email your single line diagram, load list and system fault level and our engineers will come back with a technical offer. Not sure what to send? See what a panel manufacturer needs in order to quote accurately.