Solar Inverter PCB Copy: Repair, Maintain and Rebuild

A solar inverter PCB copy is the practical route when a string inverter or micro-inverter board is out of production, the manufacturer no longer supports it, and you still have fleets in the field. We work from a physical sample and rebuild the layer stack, the netlist, the BOM and manufacturable Gerbers, so you can build replacement boards. The hard part is rarely the copper — it’s the DSP firmware and the isolation geometry.

What actually needs recovering on an inverter board

Solar inverter assemblies split into three or four distinct board types, and each one behaves differently under reverse engineering. Knowing which one you have on the bench tells you most of what the job will cost and how long it will take.

Power stage boards

These carry the IGBT or SiC half-bridges, the DC link electrolytics or film caps, current sensing shunts, and often 2 oz to 6 oz copper. They tend to be two- or four-layer with wide polygon pours and deliberate creepage slots milled into the substrate. Copper recovery is straightforward. What takes real time is measuring the copper weight accurately, capturing the exact clearance between the PV+ / PV- side and the AC side, and confirming the board material — many of these run high-Tg FR-4 or a hybrid stack because the heatsink interface sees sustained thermal load.

Control boards

This is where a C2000-class DSP, an auxiliary MCU for communications, the MPPT loop, isolated gate drive signals and the anti-islanding logic live. Typically four to eight layers, fine-pitch QFP or BGA, and dense. Layer count matters here — a control board with buried planes needs proper layer-by-layer separation and imaging, and inner-layer work is what stretches the schedule.

Driver, sensing and communications boards

Gate driver cards with optocouplers or digital isolators, AC/DC metering front ends, RS-485 or PLC interface boards, and display panels. These are usually the quickest wins. They’re also the boards that fail most often in the field from heat cycling and surge events, so they’re the most common single-board request we see.

How a solar inverter PCB copy runs, step by step

The sequence below is what actually happens to your board. Nothing here is guesswork; each stage produces something the next stage checks against.

1. Intake and photographic record. Both sides shot at high resolution before anything is touched, plus close-ups of every marked component and every conformal-coated area.
2. Electrical and mechanical measurement. Board outline, hole diameters, milled isolation slots, copper thickness, dielectric thickness per layer, and the exact position of any heatsink or busbar mounting hardware.
3. Component identification. Every part read, cross-referenced to a datasheet, and logged with package and value. Sanded-off or house-numbered parts get identified electrically — measured in-circuit or after removal — and flagged in the BOM as inferred rather than confirmed.
4. Coating and component removal. Conformal coating is chemically softened, not scraped. Parts come off in a controlled sequence so pad geometry survives intact.
5. Layer imaging. Outer layers scanned first, then the board is delaminated and each inner layer imaged individually. Nothing is interpolated from a light-box guess.
6. Netlist build and continuity verification. The reconstructed netlist gets checked point-to-point against the original sample. Every net, not a sample of them. On a high-voltage board this step also catches any place we’ve accidentally shortened a clearance gap.
7. File generation and design-rule review. Gerbers, drill files, stackup, pick-and-place and BOM. We run the recovered design against IPC-2221 clearance tables for the working voltages present, because a DC bus at 600–1000 V has non-negotiable spacing requirements and a copy that drifts by half a millimeter in the wrong place is not a copy, it’s a hazard.
8. Prototype and functional check. If you want it, we fabricate and assemble a first article and test it against your original under load.

Detailed process notes and the full deliverable set we hand over are worth reading before you brief us, so we can skip the parts you don’t need.

The firmware question, and why it decides the whole project

Copper is a solved problem. Firmware is where solar inverter projects succeed or stall.

An inverter control board without its firmware is an inert PCB. The MPPT algorithm, the PWM modulation scheme, the grid-code protection thresholds, the anti-islanding detection — all of that lives in the DSP’s flash. If you own the design and have lost the hex file (contractor gone, drive failure, engineer retired), firmware recovery is a separate service that runs alongside the board work.

Feasibility depends almost entirely on the part and how it was configured at production:

Two honest points. First, calibration constants matter as much as code. Many inverters store per-unit current-sensor gain and voltage offsets in EEPROM, and a board built from perfect Gerbers with generic calibration will read power incorrectly. Ask us to dump the EEPROM as well as the program flash. Second, we don’t guarantee any specific chip. We evaluate the part, tell you what we think is realistic, and if the answer is no you hear it before you spend money.

Firmware work is only appropriate where you hold the rights to the design — maintaining your own product, servicing equipment you own, or authorized failure analysis. That’s a condition of taking the job, and everything runs under NDA either way.

Where a solar inverter PCB clone gets difficult

Six things reliably make these jobs harder, and you should know about them before you commit budget.

• Potted and encapsulated modules. Some gate drive and auxiliary supply blocks are potted in filled epoxy. Removal is slow, sometimes destructive, and occasionally the internal magnetics can’t be characterized well enough to specify a drop-in equivalent.
• Custom magnetics. The boost inductor, the common-mode chokes and the flyback transformer for the housekeeping supply are frequently custom-wound with no part number. We can measure inductance, DCR, turns ratio and core geometry, but reproducing a custom core material exactly means finding a winding shop willing to work from measurements.
• Failure damage on the sample. Inverter boards usually arrive because something exploded. A carbonized track or a blown MOSFET that took the pad with it means that net has to be reconstructed by inference from the surrounding circuit. A second, working sample removes the ambiguity — send one if you have one.
• Obsolete power semiconductors. Older IGBT modules and specific opto-isolators are simply gone from distribution. That turns part of the job into obsolete component replacement, which means re-checking gate drive strength, thermal margin and footprint compatibility rather than just swapping a line in the BOM.
• Certification. A rebuilt inverter board doesn’t inherit the original unit’s grid-connection approval. If you’re producing units for sale rather than servicing an installed base, budget for re-testing. We can hand you a manufacturable design; we can’t hand you someone else’s certificate.
• ASICs and mask-programmed parts. If the design hangs on a proprietary controller ASIC with no second source, a straight copy may not be viable, and a partial redesign of that function becomes the honest recommendation.

What to send us, and what you get back

Getting a real answer quickly comes down to what’s in your first message. Send this:

• Photos of both sides of each board, whole board in frame, laid on a dark non-reflective surface, good even light, in focus. Add close-ups of the main controller and any part whose marking is faint.
• Board dimensions and your best guess at layer count.
• The controller marking, character for character, including the suffix — TMS320F28035PAGT is a different job from TMS320F28377D.
• One line on deliverables: Gerbers only, full schematic and BOM, firmware too, or built-and-tested boards.
• Quantity and context. Five spares for an installed fleet and five hundred units a year lead to different recommendations.

What comes back from us is a feasibility assessment naming the specific risks on your board, a lead time, and a price. Pricing on inverter work is driven by layer count, board area, component count, whether fine-pitch BGA is present, whether custom magnetics need characterizing, and whether firmware is in scope. Anyone quoting a flat rate before seeing photos is guessing.

How long it takes

A two-layer driver or interface card with recognizable parts is a short job — days rather than weeks. A four- to six-layer control board with a fine-pitch DSP takes meaningfully longer, because inner layers are imaged one at a time and the netlist verification pass scales with net count. Firmware runs on its own clock and is the least predictable element; some parts resolve fast, some don’t resolve at all. Add time if you want prototypes fabricated, assembled and load-tested, which on a power board is worth doing.

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