Solar panels come off for roof work (a re-cover, a full tile replacement, work to the structure underneath) and go back on once it is finished, and most of the time that is uneventful. The failure that matters is invisible by design: a string left unplugged, an optimiser not re-paired, a connector not quite pushed home, or the array reconnected in a different order, and none of it necessarily trips an error: it typically shows up only as lower output, not as a fault code. The inverter restarts and the app shows it producing, so the only sign that part of the roof stayed dark is your own daily production, checked against the days before the work and against what the weather actually did.
Who’s responsible for removing and refitting solar panels
A roofer’s trade is the roof: stripping the covering, re-battening, re-covering, flashing. HSE treats fitting or adjusting solar panels as a separate task on a roof, not roof work itself, and expects whoever does it to be trained for working at height on roofs. HSE also records that roof work accounts for a quarter of all deaths in construction, most of them falls from an unprotected edge or through a fragile surface.
Reconnecting the electrics is a further, separate skill. HSE’s electrical safety guidance says alterations to an electrical installation should only be done by people who know the risks and the precautions needed. Re-terminating a string, re-pairing an optimiser to its inverter, or reconnecting a microinverter is exactly that kind of alteration. Ask whoever does the reconnection whether your network operator needs to be told about the job.
MCS is the UK’s certification scheme for microgeneration installers and equipment. If your system is MCS-certified, ask MCS or your installer before the work starts whether it needs re-commissioning paperwork once someone other than the original installer has removed and refitted it.
What to agree before solar panels come off for roof work
On many domestic jobs this is two firms, or two people from one firm wearing different hats: the roofer for the physical removal and refit, whoever is competent to test and reconnect the electrics for the rest. Before the scaffolding goes up is the time to settle, in plain terms:
- Who removes the panels, and who refits them: the same person or firm, or a handover partway through.
- Who stores the panels while the roof is being worked on, and where (the next section is why this matters).
- Who reconnects and tests the array, and whether that happens the same day the panels go back on, or as a separate visit days later.
- Who actually re-commissions the system, which means confirming every string, optimiser or microinverter is reporting again, not just that the inverter has restarted.
- What your own panel and inverter warranties say about work carried out by someone other than the original installer. It varies by manufacturer, so read yours before the work starts.
Handling and storage
Solar panels are glass-and-frame units joined by connectors meant to be mated once, on installation day, and then left alone, not treated as a plug you disconnect and reconnect the way you would an appliance. Two ordinary things go wrong when panels come off and go back on:
- A connector does not get pushed fully home on reconnection. It can look connected at a glance while still making poor contact.
- A cable gets pulled, kinked or stood on while panels are stacked on the roof or carried across it, and the damage does not show until damp gets into it, which can be weeks later.
There is a subtler version, too. If the array goes back in a different physical order than before (strings swapped, an optimiser moved to a different panel from the one it was paired to, a microinverter connected to a different unit), any layout map your monitoring holds no longer matches reality. Every panel can be producing and the map can still be wrong, or a real gap can sit in the wrong place on it. So “the app looks fine” and “the array is correctly reconnected” are two different claims.
Re-commissioning is more than power coming back on
Once the electrics are reconnected, the inverter will very likely power up and report current output as soon as there is sun on at least one working string, which says nothing about whether everything that was there before the roof job is reporting again.
A proper check confirms that every string, optimiser or microinverter that was reporting before the work is reporting again after it, not just that the total is above zero. How finely you can see this depends on what your system reports. A plain string inverter typically reports at string or whole-array level: a bad connector on one panel can take out that panel’s entire string, and you would see the string underperform without being able to tell which panel or connector caused it. A system with panel-level optimisers or microinverters can show a fault down to a single panel, because each one reports on its own.
Solar panels not producing after roof work: why it still looks fine
None of the faults above necessarily trips an error message. A string that never got reconnected does not stop the rest of the array producing, so the inverter has nothing to complain about: it is doing exactly what it is designed to do with the strings that are live. The same pattern can show up for reasons that have nothing to do with roof work, too. In the case below, production fell and the inverter showed no error, and the owner only found out when they checked the string-level figures themselves:
Since installation the generation figures have been slightly lower than before but I put this down to cloudier weather and deterioration of the solar panels. However when I checked the inverter I noticed that whilst string 2 was working fine, string 1 had the correct voltage (360v) … but the ampage was zero and hence not generating any output. The inverter appeared to be working fine and had no error messages.
You cannot see a dark string from the ground, or from a green light on the inverter. The only record that shows it is the one the inverter has been keeping the whole time: your daily production, in kWh.
The check: your own production history, before and after
Most manufacturer apps and monthly reports give you daily kWh, going back weeks or months. The method is the same one worth using any time output looks off, not only after roof work: pull the daily figures for the fortnight or so before the job and every day since, then compare the days after against the days before, and against what the weather was actually doing on each of those days. A run of overcast days after the work will look like a drop with nothing wrong; a run of clear days that still comes in low is the number worth acting on. The full method, with worked examples, is here: how to check your solar production against the weather.
If a specific part never comes back rather than the whole system (one Enphase microinverter still dark, a Growatt datalogger showing a red light, a SolarEdge error appearing where there was not one before), the brand-specific checks are the next step: Enphase microinverter not reporting, Growatt datalogger red light, SolarEdge error codes. If the whole system stayed dark rather than one part of it, start with inverter offline, not producing instead.
What a quiet string is actually worth
Solmiro makes that comparison for you every day: it works out what the weather over your roof allowed, and it e-mails you when production falls well short of that or stops. Connecting is free.
Questions owners ask
Do I need an electrician to reconnect solar panels after roof work?
Whoever reconnects the array needs to be competent for it – HSE's general electrical safety guidance treats alterations to an electrical installation as work that needs someone with knowledge of the relevant risks, not a general skill. If your system is MCS-certified, ask whoever does the work whether any re-commissioning paperwork applies to your job.
Does removing and refitting solar panels affect the warranty?
It depends on the manufacturer. Read what your own panel and inverter warranties say about work by someone other than the original installer before the roof job starts.
How do I know if my solar panels are still producing properly after roof work?
Not from looking at the roof, and not from the app's live figure alone – compare your daily production in kWh for the days after the work against the days before it, and against what the weather was actually doing on each day.
What usually goes wrong when solar panels are taken off and refitted?
A string left unplugged, an optimiser not re-paired to its original panel, a connector not fully seated, or the array reconnected in a different physical order than before. None of these necessarily trip an error message on the inverter – typically they show up only as lower output, not as a fault code.
Will the inverter show an error if a string wasn't reconnected properly?
Not necessarily. As long as at least one string is live, the inverter reports normally, because it is producing exactly what the connected strings give it. A string left unplugged or a half-seated connector typically shows up only as lower total output, not as a fault code.