Solar supply on test reports

Sparkingchip said:

Think like Gas Safe, core competencies plus specific training for specialist installations and appliances.

Well, yes for Solar PV (to an extent), but no (for some prosumer's electrical installations with capability of operating in island mode)!

If a prosumer's installation supplies some (but not all) of an installation with island mode capability, and not all electricians (or the general public) know that there isn't a single point of isolation ... then sadly, "turning off the main switch" won't help you.

... and neither can you determine whether BS 7671 requirements are met for all final circuits in this type of installation, for all modes of operation of the installation.

... unless you have the "update" or "limited competency".

It's not just an "installer" thing, or a "limited competency" thing we're talking about here - I believe it's a "core competency" that's changing.

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 see your point, but I wasn't so much suggesting that 50p/item brigade take on inverters, but more that the industry as a whole makes sure it includes all electrical equipment of an installation somewhere within the environment of safety checks.

Also if we go down the route of saying that anything unusual requires a specialist to check its safety then the whole things starts to get very cumbersome for the householder - if we exclude the PV system, the gas boiler (because it's gas), the heating controls throughout the building (because they're beyond the boiler), the immersion 'cos it's on an unvented cylinder and so needs someone with a G3 cert (or whatever it is this week) to understand the multiple layers of safety devices, or the heat pump and its wiring between indoor and outdoor units, EVSE, etc, then the inconvenience and cost will conspire to mean that none of it happens properly in practice, or worse much expense is incurred but overall safety is still lacking.

   - Andy. 

The last training course I did was in January, just over four weeks ago.

I updated my “Basic Chainsaw Maintenance and Cross Cutting” qualification by doing the two day Lantra course at Hartpury College, an agricultural college with university status.

I previously did the training in 1989, there’s a recommendation to update every four or five years, obviously I missed a few updates, but actually I did still have all the basic core skills and knowledge, but after thirty two years it was worthwhile updating and it was also worth it to get out and spend time with people from a different background that have a different outlook on life. Due to the nature of the course close supervision is required and so only four students are allowed on each course, the other three are all in their mid twenties, so I’m old enough to be their grandad, this course is the “core competence” training there’s a multitude of training courses to progress to the others are planning felling and tree climbing, I have actually booked a pole saw course next month, as I said to the lecturer, the other students and the guy from Lantra who was there assessing the training on behalf of Lantra, at my age I’m not planning to climb trees but there’s plenty I can do with two feet on the ground.

Prior to this training course I did the brush cutter course at the Royal Agricultural University Rural Innovation Centre near Cirencester and the hand held hedge cutter course in a Second World War asbestos Nissen hut on the edge of a former airfield in Somerset. Along the way I have trained alongside men and women who are self employed farmers and landscapers, work for the National Trust, Bristol Water, Network Rail contractors as well as volunteers working for charities.

When I talk about training with people working in agriculture, landscaping who are actually doing it they say they have really benefited from it, there are a lot of untrained people who will argue the toss that they don’t need training, but if you watch them working it is very easy to see that they have not been trained.

However I have not been so impressed with electrical training courses over the last few years, the 18th Edition qualification is barely fit for purpose, yesterday I drove over two hundred miles to sort out a combi boiler condensation pump, a guy went to change the pump on Friday and blew the fuse in the boiler supply and the fuse in the boiler itself. The root cause of all the problems was a kink in the discharge pipe in the cupboard under the sink, you would not believe how much trouble this has caused.

I was talking to the customer who is in his eighties whilst drinking a coffee and eating a hot cross bun, as you do. The basic gist of our conversation was that guys who proudly proclaim that they are qualified because they did an apprenticeship over forty years ago, but have not updated their qualifications since then and work in isolation on their own without having the benefit of working with others to gain knowledge and experience from their peers are not the people you want working in your home.

However, the biggest issues tend to be due to people not being prepared to actually say “I don’t know” and who don’t know their own limitations, the worst being those who don’t know enough to know what they don’t know.

When I was doing my practical chainsaw assessment slicing logs up by pushing the saw through the centre of the log and working in both directions the lecturer said “You made that look easy and look like you like you could do it all day long if someone was paying you” I thought I’ll take that!

Sparkingchip said:

However, the biggest issues tend to be due to people not being prepared to actually say “I don’t know” and who don’t know their own limitations, the worst being those who don’t know enough to know what they don’t know.

Exactly! A little humility goes a long way.

I must say that a hedge cutter course seems rather OTT. I expect that quite a lot would be about safety rather than cutting the sides to a batter and making the top flat and level, but the legislation is about "at work etc." and not "at home" so I shall carry on as I always have done.

The guy I sat next to on the handheld hedge cutter course is an aerial access technician working for a Network Rail contractor.

He had the biggest and heaviest Stihl hedge cutter I have ever seen, I tried it out and it’s a monster. He said it’s okay because he never lifts it above waist height, they work from the top of embankments and retaining walls suspended on ropes with a chainsaw and hedge cutter on lanyards working their way down, so the debris falls away from them.

He was the only guy doing the City and Guilds, for the Lantra award we were trained and assessed by the trainer on the day, he did exactly the same training but then had to arrange to do a separate assessment on another day for the C&G award.

There is not supposed to be any real distinction between the Lantra and C&G awards, but the rail industry wants C&G. The only issue with this is actually being able to book an assessment, as it’s not viable for assessors to do individual assessments, basically they need to be able to do three at the same location to make it worthwhile financially. 

All this started because I was subbing to an electrician who had several housing association maintenance contracts and was going down the “Facilities maintenance” route rather than being a straightforward electrical contractor, there’s far more money in void maintenance getting some guys to paint an empty flat than there is in purely electrical work.

Just to help others that may look at this post. I have been digging around in books and found some useful bits.

Guidance note 7, special locations chapter 10 Solar PV installations has some useful information

Practical guide to Inspection, testing and certification, 17th edition chapter 10 has similar content

Couldn't find anything significant in GN3

I would assume that IET code of practice for grid connected solar would be informative, so far have not purchased but probably need to.

Things I have picked up from reading the above and my thoughts

If the solar system isn't going to work in Island mode then the overall impact on testing is probably limited. If the system provides back up facilities with batteries and island mode operation system design and testing becomes significantly more complex.

Going back to the basic solar system without backup I don't think it's practical for standard EICR's to cover anything above the roof line due to access issues, I also suspect that companies installing and offering long guarantees will not want anyone going near their system anyway. maybe some companies will claim they can check thigs from a ladder with cameras on a pole or something but I don't see how structural and electrical integrity can be checked without giving things a good push and pull, plus moving cables to check for abrasion issues and cracking.

Providing that the input and output of the inverter have been isolated performing standard insulation and R1+R2 tests to the isolator switch is fairly straight forward. I personally would be very nervous about doing insulation tests unless i was sure that I could isolate the expensive inverters and panels from the test. I think if I was doing the test I would want to measure open circuit voltage and short circuit current of the panels before and afterwards so that I have a record if someone tries to claim I damaged one of their panels.

It appears most legacy systems will have the inverter as near to the panels as possible as rules for DC cable runs through houses are more onerous.

Inspection of the accessible AC and DC wiring should also be fairly straight forward.

It's probably not to difficult to test the DC wiring up to the 1st isolator in the system so that the panels are isolated from the test.

If changing a distribution board where the solar is connected and an RCBO is required the RCBO needs to be bi directional and may need to be type B depending on how well the inverter isolates the AC output from the DC supply.

For TNCS unless the panels are class 2 the mounting frame should not be connected to the suppliers earth facility but to an earth rod, I don't know but my guess is that most panels will be class 2 to overcome this.

When looking at the newer systems with battery walls and backup things change significantly

Much more difficult to fully isolate the system

For best efficiency the battery and solar will be DC coupled with a shared inverter driving longer DC cable runs through the property with more onerous rules for cable protection

In island mode the backup system will need it's own TT earth which will need testing

I feel like I am beginning to understand more about these systems and realise how much I don't know.

The biggest problem is that the general standard of PV and battery storage installations is very low and often unacceptable, so inspecting and testing these installations will soon get very involved.

Alan B said:

Guidance note 7, special locations chapter 10 Solar PV installations has some useful information

Practical guide to Inspection, testing and certification, 17th edition chapter 10 has similar content

Couldn't find anything significant in GN3

I would assume that IET code of practice for grid connected solar would be informative, so far have not purchased but probably need to.

There is also an IET Code of Practice for Electrical Energy Storage Systems for the battery side of things.

In island mode the backup system will need it's own TT earth which will need testing

It'll need it's own local electrode, but the resulting system will almost certainly be TN-S (in island mode) rather than TT. It's the equivalent of source electrode that's being added rather than the consumer's one.

   - Andy.