Who Pays to Replace a Failed Solar Inverter?

A string inverter fails in year nine. The manufacturer honours a twelve-year warranty without argument and ships a replacement unit at no charge.

The homeowner then discovers that the workmanship warranty covering the labour ran for ten years on paper but was written by a company that closed in year six, that the replacement is a current-generation model rather than the one that failed, that the monitoring gateway does not talk to it, and that the building department wants a permit because the electrical work is being altered.

Every document in the file is being honoured exactly as written. The bill is still four figures.

Two warranties, two clocks, one job

The reason inverter replacement generates so much friction is that a single physical task sits across two separate promises with different terms, different obligors, and different expiry dates.

Read that table down the middle and the gap is obvious. On module-level electronics the parts term can be twenty-five years while the labour term is a fraction of that, so for most of a system's life the part is free and the visit is not.

This is a specific instance of the general pattern set out in who stands behind a solar installation warranty: several overlapping instruments, each doing exactly what it says, with the expensive cases falling between them.

By financing structure

Owned, cash or loan. The homeowner owns the equipment and owns the labour cost. The parts claim goes to the manufacturer; the labour is theirs unless a service agreement or an in-term workmanship warranty says otherwise. A loan makes no difference to this — the debt and the maintenance obligation are separate, which is the same point that makes permanent removal more expensive than people expect.

Leased or PPA. The provider owns the equipment and carries both parts and labour, because a system that is not producing is not earning it anything. This is the arrangement where inverter replacement is genuinely somebody else's problem, and it is one of the more concrete practical differences between financing structures — the sort of thing that belongs in a comparison rather than left implicit. Our note on TPO versus loan versus cash covers the wider trade.

Replacement is rarely like-for-like, and that has consequences

Inverter product cycles are shorter than inverter warranty terms. A unit that fails in year nine will frequently have been discontinued, and the manufacturer supplies a current-generation equivalent instead.

That substitution is reasonable. It is also not a swap.

Monitoring and communications may not carry across. A successor unit can require a different gateway, a new commissioning of the monitoring account, or a different reporting path. This is how a warranty repair quietly becomes a monitoring outage: the system produces, the portal does not report, and nobody notices for months because nobody was assigned to notice. That is the failure described in who is responsible for monitoring after PTO, arriving by a route nobody anticipated.

String configuration needs checking rather than assuming. Input voltage and current limits differ between generations. An array wired for the original unit may or may not sit comfortably inside the successor's window.

The AHJ reviews new work against today's code. This is the one that changes the scope. An inverter replacement is an alteration to an electrical installation, and where a permit is required the authority having jurisdiction generally applies the code edition in force now rather than the one the system was built under. Current rapid-shutdown requirements are the common example. So bringing the affected portion of the installation up to current requirements can become part of the job.

That is the same rule that makes an expired permit expensive rather than merely annoying — the standard moves, and work re-reviewed later is re-reviewed against the standard of the day. Who is responsible when a solar permit expires sets out the mechanism, and what an AHJ is covers why the answer differs between neighbouring jurisdictions.

When the original installer is gone

The two warranties fail differently on insolvency, and the asymmetry is unhelpful.

The manufacturer's parts warranty survives, because it is the manufacturer's promise about its own product and does not depend on the installer existing. The workmanship warranty does not, because it was a promise by an entity that no longer exists to keep it. That asymmetry holds only while the manufacturer itself is trading — the mirror case, where the equipment maker is the party that failed, removes the half that normally survives and leaves nothing else in the stack to cover a defect in the goods.

So the homeowner keeps the half that was already going to be honoured and loses the half that covered the money. Claiming directly on the manufacturer is normally possible but needs evidence the installer would have held — serial numbers, proof of installation date, often the commissioning documentation. Monitoring account access is frequently the other casualty. Our note on what happens when an installer goes out of business covers the recovery route.

The preventable part of this is documentary. Serial numbers and commissioning records collected at handover cost nothing; reconstructed from a defunct company's records they may be unobtainable. That is a closeout item, and it belongs with the rest of the closeout package.

The lost production nobody covers

Both warranties conventionally exclude consequential loss, and lost generation is a consequential loss. The unit gets replaced, the labour gets paid, and the electricity that was not generated is simply gone.

A written production guarantee can change that, where one exists — though these commonly require the owner to have reported the problem promptly, which an unmonitored system makes impossible.

The size of the loss is therefore set by the lag, and the lag is a detection question. A total inverter failure is one of the few faults a homeowner reliably notices, because the electricity bill moves. Even so, the typical lag is a billing cycle or two, and on a system where a partial failure is possible the lag can run to months. Our note on who pays when a system underproduces follows that through to the true-up statement.

What to do at the point of sale, if you sell these systems

On a twenty-five-year system with a ten-year inverter warranty, at least one replacement is a foreseeable event. Treating it as one is both more honest and commercially better than the alternative.

There are three defensible positions.

1. Disclose and hand over. One sentence at handover: the inverter is warranted for parts for N years, labour is covered for M years, and after that a replacement is a cost you will bear. Then give them the serial numbers and the commissioning record.
2. Sell coverage. A service agreement or an extended plan that includes labour converts a year-nine grievance into current revenue.
3. Route it to somebody who carries the function. For a sales-only organisation with no service crew, this is the only version of option two that actually works.

The failure mode is the fourth option, which is not a decision at all: letting a homeowner infer from a stack of warranty paperwork that everything is covered for twenty-five years. That is what the paperwork looks like if you do not read the labour exclusions, and the inference surfaces in year nine as a complaint about something that was never promised.

Where this belongs in a project's documentation is the same place as monitoring, insurance and permit records — the project responsibility matrix exists to make those allocations explicit rather than assumed.

The bottom line

Inverter replacement is one job across two warranties. The manufacturer covers the box; the installer's workmanship warranty covers the visit; the two expire on different dates and only one of them survives the installer closing. On an owned system the labour is the homeowner's, and on a discontinued model the job may also carry a monitoring re-commissioning and a code-current compliance review.

None of that is a defect in how the industry writes warranties. It is a predictable consequence of how they are structured, which means it can be planned for at the point of sale in a single sentence, or discovered in year nine as a grievance.

Seamless Home carries the back-end scope that makes the first version possible — design, permitting, procurement, project management, closeout and service coordination — for sales organisations, installers and EPCs that would rather not build the function in-house. Coverage is confirmed per service area rather than promised as blanket availability.

If you would rather post-handover service had a named owner, get in touch.