A yield loss – the system produces nothing or significantly less than usual – usually has one of a few causes: inverter fault, tripped fuse, a grid-side problem or simply a dead data connection that only feigns a failure. It is crucial to notice the standstill quickly: every week of unnoticed failure costs yield that no one will bring back. Notice, isolate, specialist company – in this order. (As of: July 2026)
Key points in brief
- The most expensive yield loss is the unnoticed one: without monitoring, a standstill often only becomes apparent with the annual statement.
- The most frequent trigger is the inverter – as the only component with real electronics, it is the expected weak point.
- Not every reported failure is one: an interrupted data connection shows zero while the roof produces normally.
- A summer month of standstill weighs many times heavier than a winter month – the annual curve decides the damage.
- Who pays depends on the cause: defect → guarantee, damage event → insurance, age → provision.
How do you notice a yield loss at all?
In the best case by the alarm, in the worst case by the electricity bill. Modern systems report faults via the monitoring app – provided the notifications are set up and have not been landing in a silent inbox for months. Systems without supervised monitoring, on the other hand, have a structural problem: a solar system at a standstill looks exactly the same from the outside as one that is producing. No sound is missing, no light goes out – the household simply draws everything from the grid again, and that only becomes apparent when someone compares numbers.
Therefore the most important rule of this article, even before any troubleshooting: set up the fault alarm, today. And at the annual check, take a look at the production figures compared to the previous year – same month against same month.
What are the most frequent causes?
| Cause | Typical picture | First point of contact |
|---|---|---|
| Inverter fault or defect | System at a complete standstill, error message/status LED on the device | Rectifying inverter fault |
| Tripped fuse / RCD | Standstill after thunderstorm or work on the house grid | Check fuse box, in case of repetition specialist company |
| Grid-side cause | System switches off and on again, often neighbourhood-wide | Grid operator / specialist company |
| Dead data connection (feigned failure) | App shows zero, meter continues to count normally | Check router and connection |
| Damage event (storm, hail, lightning) | Standstill after severe weather, if applicable visible damage | document, initiate claim process |
| Partial failure of a string | Production significantly reduced, but not zero | Specialist company – diagnosis as with reduced yield |
Classification, As of: July 2026. Electrical troubleshooting belongs in expert hands – amateur work ends at the fuse box.
The inverter does not lead this list by chance: it is the workhorse with power electronics and thus the component whose failure in the system's life is simply to be expected. Significantly more harmless, but surprisingly frequent, is the feigned failure – the system is producing, only the message no longer arrives. This check costs nothing and therefore belongs at the beginning.
How do you proceed specifically in the event of a standstill?
Firstly: rule out a feigned failure. If the private electricity meter shows feed-in or noticeably low consumption during the day, the roof is producing – then the data connection is the problem, not the system. Secondly: look at the inverter – note down or photograph the display, status LED, error code; this speeds up any diagnosis later. Thirdly: check fuses and reset once – not repeatedly; if it trips again, there is a reason for it. Fourthly: call a specialist company, with the error code and time of the failure.
What does not belong on the list: the roof. Troubleshooting modules and wiring is professional work with a risk of falling and electric shock – after severe weather, this applies all the more. Your contribution is observation from below and documentation; everything from the first screw is our profession.
What does a failure cost – and why is the timing crucial?
The calculation is unpleasantly simple: lost self-consumption savings plus lost feed-in, for every day of standstill. The good news lies in the annual curve: production is distributed extremely unevenly over the year, a large part falls in the summer half-year. A failure in December is therefore annoying, but bearable – the same failure in June costs a multiple.
From this follows the priority rule for an emergency: in summer, every day counts – report the fault immediately and press for a speedy repair. And in general: the reaction time is the only part of the damage that you yourself have in your hands. Between «alarm on Tuesday, technician on Friday» and «noticed after six weeks», for a typical single-family home system, lies the difference between petty cash and a noticeable hole.
Who pays for the failure?
That depends on the cause, and the answer has three addresses. Defect of a component: Within the deadlines, the guarantees apply – how the processing works and who is responsible for what is described there. Important: The guarantee generally replaces the component; the lost yield during the standstill is a separate topic and, depending on the contract, is not covered. Damage event: In the event of a storm, hail or lightning, the case runs via the insurance – whether the yield loss itself is also insured depends on a possible yield loss cover; for single-family homes, it is a consideration, not an obligation. Age: The inverter at the end of its life is neither a guarantee nor an insurance case, but planned maintenance – the provision for this belongs from the start in the operating costs calculation.
The painful cases in our region almost always follow the same script: the system ran inconspicuously for years, the monitoring had quietly quit its service at some point – and with it the attention. The standstill only became apparent on the utility's annual statement, months later. The repair itself was then usually a manageable intervention; the actual damage was the lost time. Our standard recommendation since then: the fault alarm belongs on two channels and to two people – technology fails, habits too.
Frequently asked questions
How quickly must a failure be repaired?
As quickly as possible in summer, with a little serenity in winter. Depending on the spare parts situation, days to a few weeks are realistic – in the event of a total inverter failure, the specialist company queries the availability and can sometimes check a transitional device.
Does the insurance pay for the lost yield?
Only with corresponding yield loss cover, which is to be agreed separately. For single-family home systems, the potential failure amount is usually manageable, which is why many do without it – a consideration, not an obligation.
Is a partial failure also a yield loss?
Economically yes – a failed string can significantly depress production and gladly goes unnoticed without monitoring. For troubleshooting, the same procedure applies as with creeping reduced yield.
Can I restart the inverter myself?
A documented restart according to the manufacturer's instructions yes – nothing more. If the fault repeats, the restart is not a solution, but postponing the diagnosis.
Does a maintenance contract prevent yield losses?
Not prevent, but shorten yes: supervised monitoring notices faults immediately, and defined response times speed up the repair. Whether this is worthwhile depends on the system and your own commitment.
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Is your system at a standstill – or do you not even know?
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Operating and service practice of ecoEn GmbH, Zurich region (as of July 2026); Swissolar.
Last updated: 9 July 2026 · Author: ecoEn editorial team
