Micro inverters - Check with DNO

[Energetic]

I have been advised by WPD, my DNO that they are sending a letter advising all customers who notify with micro inverters that they must be disconnected untill a G83 compliance certificate can be provided for the whole install. A generic one for the unit is not acceptable.

I have not done a micro job yet so not sure if this is as bad as it sounds, but to me it sounds pretty serious. Has anyone else heard anything like this?

 

[Worcester]

Can you forward me the note - PM me and I'll send you my email address or you can get it off our website, and I'll raise it with Enecsys and see what they have to say.

 

[BruceB]

Someone I have quoted for said something similar to me about WPD about a week ago, but I have not followed it up with WPD yet. I would also be interested to see any letter the DNO sends out as WPD covers most of what I do now since they have taken over Central Networks. I am not sure WPD are on solid ground if you are connecting them under Stage 1 arrangements and they have a valid independently issued G83/1 certification. I wonder whether they are confident enough to invoke the arrangements of S34 of ESQC regs if someone refuses to disconnect?

I have one customer and one potential customer who have declared they want to go the micro-inverter route so it affects me.

It would be a crippler for Enecsys who I suspect are working hard to bring the Duo to market to make the micro-inverters more affordable.

Regards
Bruce

 

[Energetic]

I have nothing in writing, my contact asked me about them verbally having received the guidence from 'up high'.

A couple of months back i really thought they would be the future for PV, they seemed to be the solution for all our shading issues but PV sol expert doesn't rate them very highly against a modern HF type inverter, their compatability is fairly limited and now this. I hope for their sake WPD are the only ones... and they change their policy...

 

[Energetic]

PS, have informed my contact at Enecsys also.

 

[edexlab]

I've recently notified WPD on our first enecsys job a fortnight ago and received an email asking have you preapplied for this project 4kw ,which was done while they were still Central networks ,I sent back their approval letter and today received the usual authorisation to connect letter, otherwise no problems It seems to depend on who gets the paperwork on there desk as some of their staff query what should be a routine job and I get the impression they are for the most part quite clueless with what they should be doing , ps got another one to do tomorrow

 

[Worcester]

Seems like at least one company know how to deal with and sort these kind of problems and aren't afraid to admit, repsond, and solve - great to see, well done enecysys ( Enecsys sent me this, this morning):

We have been notified this morning that Western Power have sent letters out to all home owners whose solar systems include Enecsys micro inverters, telling them to decommission their systems.

This is because Western Power is asking that our inverters, despite being G83 certified, be further tested with regard to our systems connecting specifically to their network. We are currently undertaking those tests which will take another 3 to 4 weeks to complete.

Please note that Western Power are the only DNO with an issue with our current certification, but we are having to comply with their needs.

We apologise for any inconvenience this disruption may cause to your customers and will contact you as soon as all systems can be turned back on.

 

[TedM]

Just crossed my mind while reading this thread that DNOs could argue that all micro-inverter systems are actually multiple pv installs on a single site rather than a single installation. And under these circumstances G83 Stage 2 would apply - with knock-on consequences for the customer to pay an application fee and for any network reinforcement.

 

[Worcester]

@TedM

Careful how far you go with that, otherwise a 10kW three phase with three single phase inverters, etc, which is gnereally acknowledged as Stage 1.

I can see a case for G83 Stage 2 though.

 

[edexlab]

Spoke to an engineer from western power when it was central networks to see how they wanted us to format the application and they were only bothered if it went over the 16 A limit and told us to apply for it as G83/1
surely it would'nt class as stage 2 as its one site/mpan etc rather than two/more separate installs in close proximity

 

[Worcester]

Multiple generators on the same site, is what it falls under.

The generator is the inverter, the panels are the power source, as far as G83 etc is concerned, it could be 100 people on pedal bikes with dynamo's attached, just won't get a FiT !! payment on that one.

 

[TedM]

I was just pointing out a technical nicetie in the legal definition which could possibly be exploited by DNOs to increase their income.

 

[Worcester]

@TedM, sorry wasn't challenging you, you are absolutelty correct, just sometimes we let the king think he has clothes on. (else he'll start to do things different!)

 

[Von Vardo]

I had the training phone call with Enecsys this morning and asked about this issue. Apparently it's to do with the G83 certification being for one inverter on it's own and WPD are concerned about how the system works as a whole, i.e. a number of inverters connected together.

Interestingly I was advised to notify the DNO before installation even though it isn't WPD.

 

[dougalthedog]

Perhaps this should be a new thread, but looking at DGCG G83 S1 page 20 suggests that after 2nd March 2012 all panels will need to be G83 type tested.

Apart from the question of which panels are tested / will be by the deadline surely this raises a similar issue to the connection of multiple inverters - could multiple panels not be considered to be seperate sources of generation?

Taking it further, G83 stage 2 seems to only apply to "multiple SSEG units within different customer sites" so if microinverters don't come under stage 1 then presumably they will have to be G59?

More fundamentally, what is the reason that DNOs have issues here - is it a concern that multiple inverters in parallel will not detect a loss of mains correctly?

Last question, how are the requirements of DC isolation achieved with a microinverter.

I know I seem rather critical but actually I think these are a great product and the way forward for solar PV but don't want to buy something which may end up not being acceptable to DNO.

 

[TedM]

I read it a different way.

PV is a type-tested technology and listed in the Annex. The list is: CHP, PV, Fuel Cells, and Micro Hydro.

The significant one missing from this is Wind.

So PV has complied with G83/1-1, and will continue to comply, via 'route 1' and the March 2012 deadline won't apply to PV.

Small wind has so far only been eligible for G83 connection via 'route 2' so the deadline will apply to wind.

I don't know much about micro-inverters but generally, to pass G83 certification, inverters have to be capable of detecting loss of mains even in the continued presence of output from another G83 inverter. They still have to close down within the prescribed time period. If a device is G83 certified then any DNO should not have a problem with it - irrespective of how many are used.