Solar supply on test reports

Alan B said:

I haven't worked on an installation with battery but same question.

If you have not had training in installations with electrical energy storage systems, or switched standby generator systems or UPS, and aren't confident, I would advise to leave the whole installation well alone.

In some arrangements, some or all of an installation with storage batteries may be energised when you isolate the grid power, and it may take some time (a few seconds - definitely enough for you to prove dead) before automatically switching over to "island mode" (off-grid, or "backup" mode). There should be isolation instructions and notices in the installation, but I guess as always it depends who installed it, as always.

When testing, certain readings for live tests can be distorted by the presence of inverters, and there will be a need to verify earth electrode resistance if the installation has "island mode", along with ADS.

This technology is set to go mainstream, along with EV, so if you are seeing installations with this technology regularly, to be honest it's probably a good idea to plan in some courses or other CPD to get up-to-date to stay safe.

Alan B said:

Is this enough or do I need to start learning more about solar and doing more?

Again, more likely to be going mainstream, so perhaps worth planning in some CPD.

I suppose that solar is a bit like the DNO/supplier's tackle. Inspect it and then move on.

The extent of an EICR is whatever you are contracted to I&T. Whether you train up on solar is your personal commercial decision, but I think that it would be odd if a customer didn't want the whole installation tested. Indeed, if he or she is a private landlord, I don't think that there is any choice.

I have some knowledge but agree I need to improve on that fairly quickly. So far I haven't worked on any battery systems but come across solar in relationship to a couple of EV installs, where I have turned all the solar and main isolators off and run the normal safe isolations tests. Checked Ze etc for the main supply and left the solar alone, did my install and turned everything back on.

Chris Pearson said:

I suppose that solar is a bit like the DNO/supplier's tackle.

I agree that, up to now, we could deal with it like that.

With some battery storage systems, they are integrated with the installation ... and some Solar PV systems may also go that way if they contain battery storage.

With that kind of system, the game changes somewhat.

There seems to be all sort bit of the electrical installation that seem to get ignored during "normal" EICRs even though they seem to be within scope of BS 7671 - the obvious one being central heating controls. So I guess there is a precident for treating a conventional grid-tied PV system in a similar way - i.e. just test/inspect up to the AC isolator next to the inverter.

For additions/alterations on the rest of the system, as ever, you're only certifying your own new work, the 'comments on the existing installation' box is there if you happen to notice anything obvious, but I don't believe you're under any obligation to test or inspect anything existing that your new work doesn't directly rely on.

I can see an argument that I&T of solar PV systems should be seen as a specialist task - not so much from an electrical point of view, but to do a proper job will need access to the d.c. side and thus the panels themselves - which will likely mean going onto the roof will all the access equipment and working at height complications that it's probably not reasonable for a run-of-the-mill electrician to be equipped for.

As with any on-site generation, some extra care will be needed to ensure things are properly made dead - especially if a complete installation shutdown is being avoided. Generally think in terms of looking to isolate both ends of what you're working on rather than just the 'supply' end of conventional thinking - just in case the on-site generation is connected to the load end.

   - Andy.

AJJewsbury said:

As with any on-site generation, some extra care will be needed to ensure things are properly made dead - especially if a complete installation shutdown is being avoided.

Agreed - the difficulties in that may be:

• Deciding which part (or parts) of the installation are fed by the backup supply in island mode - this will change between installations, and depends on a number of factors such as the way the manufacturer of the system components arranges the switching necessary for island mode operation, and some decisions the system installer or integrator put in place.
• The fact that there can be a suitably long pause between main isolator, or power conversion equipment (PCE) isolator going off, and the backup supply coming on-line.

Of course, having adequate documentation, signage and schematics available are essential in this respect, but an understanding of system operation might also be necessary.

I worry that, as this type of system goes mainstream, we could be behind the curve in CPD for its implementation (especially for those who aren't involved in the original installation).

To illustrate this, the title of this thread is "Solar supply on test reports", we know what the OP has said and asked... yet we've had Solar PV in BS 7671 for 14 years now, and in people's homes for longer. No criticism ... and definitely an indicator of competence for the OP to know limitations, but an illustration that the industry as a whole moves far more slowly than even the standards that support it, which are often criticised for being behind innovation and the advance of technology.

we could be behind the curve in CPD for its implementation

Good point.

Now I'm thinking down that line, BS 7671 would cover the a.c. wiring to the inverter and the d.c. wiring between the inverter and the panels, but presumably the safety of the inverter itself would be treated more like a fixed "appliance" - but presumably with a few extra challenges. Does the "Code of Practice for In-service Inspection and Testing of Electrical Equipment" cover PV inverters?

   - Andy.

AJ, have you any idea of the caliber of candidates on PAT courses? I wouldn’t trust my kettle with them let alone an assessment of the safety of a PV inverter.

I do think that some of the top guys setting rules and regulations or otherwise pontificating, ought to have a good look at what’s going on at the lower levels where most of the safety inspections are conducted. 

With regard to isolating solar supplies, always remember that as long as the panels are exposed to light it will be live at it's terminals.  Surprisingly often forgotten.