Where are the inverters - i.e. where do the DC lines from the solar panels go ?

Indeed, all the time the sun is out, they should be treated with care, as the panel will be generating, regardless of what you switch off indoors.

Normally on anything more than a very small installation, the solar panel DC cables  plug in somewhere, and may be interconnected in series strings, with special DC connectors that in effect shroud you from the terminals  from both directions.  These are the safest place to disconnect them ( when you do, please label and maybe photograph first as there are many variations)


Do not be tempted to cut a cable or create a new joint while the panels are illuminated - even an overcast day can give a substantial open circuit voltage. If it is not connectorized then in effect a degree of live working may be  unavoidable, and your method of work needs to reflect that. Be aware that hopefully taping bits or cardboard to the panels will reduce the output, but  cannot always be done well due to the way things are assembled, and you do not want your cover blown off at the wrong moment...



Store the disconnected panels out of sunlight if they have to be left with open ends disconnected.

The PDF pages 20-22  (really starting at leaflet page 37 as it is in double page format) of this installer guide by BRE   may help

I agree with Mike’s comments.

Before starting work the array should be into open circuit by isolating the inverter at AC, then DC. On a larger system, I would be inclined to use a clamp meter to check nothings flowing that shouldn’t be via leakage paths... Do not attempt to pull apart cable connectors if there’s a chance that current is flowing as the arc will cause damage.

Obviously check the series/parallel configuration in the documentation before you start so it goes back the same way.

I would recommend string testing in accordance with BSEN62446 before the modules are removed and on reinstatement and comparing with design values, or at least each other.

Has the roofer worked with PV before? Do note that modules are more fragile than they appear and microcracking can arise from rough treatment / pressure (crawling over them) / overtightening clamps that may not be visible at the time but will affect performance later.