Dillsue

Only if dragsterdriver pushed a piece a wire up the inside of both MC4 connectors at the same time and held them. Probably no more lethal than working on the roof?

Solaredge do as standard but I dont think Tigo do. The Solaredge safe 1 volt output can be overriden with a Solaredge tool and then give full output in the same way Tigo units do. Best to check with a meter if you dont know the spec of the optimised system youre working on.

I think the OP sensibly came looking for clarification/advice about something he already seemed clued up on. If he already knew exactly what to do hes not likely to have posted??

I think that your eleccy supplier can upload unit rates to your display so you can see what your using in £, but if you set the display to show units it will display those

Normally, on this forum it is!😁

Normally?? Without trawling the forum I think its normally 3 or sometimes 2 letters, usually h, k and w with random capitalisation, if any😁

Read on a bit and....

Kwh last time I saw it.....sat at the inverters 16amp limit😁

You probably need to get your head round whats involved in running off grid and get the buy in of everyone whos going to use the house. Have a good think about all the things you do over winter and consider if youd be able to do those if youd had a cold dull week when the ASHP has taken virtually everything out of the batteries and PV has put nothing back in. Obviously if youve got your own solar farm and a container of batteries, going off grid is reliably feasible, but more likely the 50p/day electric standing charge is a bargain for the backup of a grid connection.

My daughters smart meter shows export and they are on a standard price capped varable tariff with no SEG

Its massively different to driving on an A road as on the salt flat theres the option for both cars to move a long way from the line and virtually eliminate the risk. Going back to the OPs level of risk and hes already got a spark on site that could megger the cables even if not taking responsibility for the full PV. The OPs questions are well written and list all the things that need doing to complete the roof work......hes just looking for confirmation. All suggests low risk to me

Nope. The OP wants to get the roof work done while he waits for a spark to come available. No mention of doing anything more than running DC cables to isolators.

Hopefully the OP can see that none of this relates to what he wants to do and can safely move his job forward and get the scaffold off hire.

With individual optimsers per panel theres a minimum of 8 units specified for all the smaller inverters which I guess is to maintain minimum power input into the inverter at lower light levels. You might hit problems with that, but maybe not. Considering Radians very valid concerns, youve nothing to loose by powering up, pairing the optimiser and seeing if it generates. Hopefully its obvious but switch the AC isolator off before unplugging and dont leave the plug unattended without ensuring no one can unplug it. Not that you should rely on these safety features but I belive the SE3680H and smaller inverters shutdown within 0.25 seconds of mains loss and they have an inbuilt RCD. If youre not clear on the risks/hazards probably best to wait for a spark to connect you up??

If youre looking for a solar experienced spark you might be waiting a while!! In the meantime, with a 2kw inverter, you could plug your inverter into the nearest 13amp socket to get it powered up for testing. Not that Im endorsing it, but you could then leave it plugged in to grab some generation while the sun shines:)

Yes, your AC isolator wiring isnt best practice but you can see from the wiring guide of the DC isolator that best practice isnt always followed. The DC isolator wiring is using 2 poles for +ve and 1 pole and N for negative, the thinking being that if 1 pole welds closed theres a second pole that should still break the circuit when the isolator is turned off. That wiring guide would have been better wiring +ve In into L1, a link fitted from T1 to L2 and +ve Out wired to T2. Same principle for -ve. Keeps the Line/live and the load on the correct sides of the isolator. Having already wired your AC isolator I personally wouldnt rework it to best practice, but maybe put some tape over the terminals fed from the CU and write "Line/live" on it. Be a reminder for you if you ever have to go back in there

Just listening to the prophets of doom citing death as close to inevitable when connecting PV modules got me thinking of what seems a more realistic situation??? OP has 2 strings of 6 panels wired into separate isolators so max voltage on either string is around 6x40vdc=240v. That 240v will be contained within a pre wired isolator. The pre wiring has an IP2x MC4 connector on the end of whats probably double insulated cable. Panels are new almost certainly having a factory QA inspection for function and integrity. Remembering that the isolators arent connected to anything yet and are in the off position, theres no circuit that can carry any current so youre not connecting any load. When you plug the first panel in youre handling MC4 connectors with circa 40 volts across them inside IP2x connectors, IF you held both plugs at once, which you dont when connecting up When you connect the second panel to the first theres no voltage across the plugs as both panels arent referenced to earth or to each other. The same principle applies as you plug in subsequent panels. When you connect the last panel to the isolator cable, theres now 240v inside the isolator but as the array isnt tied to earth, youve got to touch both +ve and -ve at the same time to get a belt, after youve taken the cover off the isolator. Maybe Im missing something but it seems pretty benign to me???

Switch the AC isolator off and the inverter should shut down, then which terminals remain live with the isolator cover off?

What is important is that you get the live conductors in L1-3 and not in T1-3. L = Line which is the incoming live supply. Unless the interlock has been defeated, you can only remove the isolator cover in the off position. In the off position the only live terminals should be L1-3 so your incoming cables from the PV array would be in L1 and either L2 or N depending on where you want to put the incoming -ve. Unfortunately the same principle applies to the AC isolator!!

G98 allows the system you describe, in fact it allows up to 16amp export on top of what you pump into the battery. Its the householders choice if they want to use kit that doesnt meet G98. If your choice of kit doesnt meet G98 but is configured for zero export then youll get permission to connect, but youll need to prove to the DNO it is actually limited to zero.

Those following the advice given on page 2 of this thread, hence the discussion!!

For any particular section of the grid, say a large housing estate, the sun shines at the same time, save for the odd passing cloud on a sunny day. I dont think voltage rise nationally is problem as large generators can probably regulate that. The issue is if there was unregulated install of PV or no requirement to notify the DNO, then said section of the grid/housing estate could have problems

Not everyone cooks at the same time and even if they did not every element on every cooker would be on at the same time. Conversly, when the sun shines everyones PV will export at exactly the same time. Volt rise can be an issue....our house voltage rises to 255 when the sun shines with a single G98 system. If I connect up a second G98 system (for test purposes), one or other of the inverters will trip on grid overvoltage which is set at 262 volts. Grid limit is 253 volt. Hopefully, that will be resolved when our DNO upgrades our transformer, but you can hopelly see that uncontrolled connection of PV can easily lead to problems.

AIUI any cable assembly that is factory made and tested can be installed by anyone ie kettle or computer lead. That principle would cover all the panel MC4 connectors connecting the panels together If the cables from the array to the inverter are prefabricated then the same principle applies. If the same cables are site assembled, as in cut to length and MC4 connectors crimped on, then they need a test and inspection. Unless youve got an inverter and consumer unit with plug in connectors and can buy a factory assembled and tested connecting lead, then the AC connection from inverter to CU always needs a test and inspection. Just my take on things and not a statement of fact!!

And immediately following that para it refers the reader to the MCS web site, yet theres absolutely no requirement to use MCS installers which the para infers is a requirement! As with the addition of any circuit to a domestic install, a new PV connection needs to be tested and inspected by a part P accreditted spark or get your local building control to test and inspect.