G59 courses

[woko]

Anybody attended one? Eco skies want 400 plus for a days course but I've found other training places that only want 225 plus.
Are they worth doing?
I'd like to learn about the application process and the G59 relays.

 

[infinity]

likewise, im looking down South

 

[Gavin A]

what size systems are you wanting to work with?

most inverters are now type tested to G59 so don't need witness testing on site, or relay panels etc. I've certainly not come across it as a requirement for below 50kW systems since type tested inverters were available.

Follow the G59 application guidance on the sticky threads in this forum and you should be fine.

Remember about the requirements for fuse protection where there's more than 3 DC strings.

there you go, that's a G59 course in a nutshell, and unless you were planning on shelling out serious wedge for the testing kit to allow you to do G59 tests on site anyway then anything else is irrelevant, and you can just hire someone in to do that on a day rate if you ever did need it.

 

[Worcester]

Anyone esle going to be with us on Tuesday wehen we get to discuss and meet with Ofgem, plus: ENA – Paul Jewell, Policy Manager, Western Power Distribution; Western Power Distribution - Robert Symons, Chief Executive ; and ScottishPower Energy Networks – Paul Brown, Connections Manager

(And they're arranging lunch cost to attend £0 ..)

Anything anyone would like me to ask them?

 

[infinity]

Thats pretty clear!

so as long as the inverters are G59 type tested up to 50 KW installations, then its just a straight forward install with pre notification to the DNO?

Also as you said were more then 3 strings then string fuses to be used to prevent reverse current flow.

I havent yet had to install these but assume its just like an inline fuse at either end of the strings?

 

[Worcester]

It's not your normal G83 pre-notification, it's usually a G59 form, the information required is straightforward though. Also in some cases WPD now have a simplified form for <50kWp using type approved, which is basically a G83 form... plus you need to send in the schematics in advance, so you need to have done the electrical dc and ac design first.

SMA inverters can optionally include electronic string fuses inside them, along with surge protection also, so it's usually very simple.

 

[woko]

Ok, thanks for the help.
So if an installation has more than 3 strings does that mean the stringsover 3 should have string fuses or all strings should have them? I'm just about to do a 20kw with a power one 20kw inverter. The software suggests 4 strings of 20 250w panels. What string fuses should I be using on this?

 

[Gavin A]

check the spec on the pwoer one inverter, but the ones we've used of those already have string fuses in them, so just plug and play. just remember that it means you can't just parrallel them up on the roof - well, you can do 2-3 at a time, but not all of them (which I nearly did one time before clocking).

tbh I wouldn't mind a bit more clarity as to what classes as being the same array on that score myself, as we've done one install where we did one side of the roof at one point, then went back and did the other side. I tended to work on the basis that the arrays were 15m apart across the ridge, and the cables were run separately, so I couldn't see the issue and didn't put string fuses in, but I'm sure others would interpret it differently.

 

[Worcester]

String fuses are to stop one string overpowering another with reverse flow.

Also just becasue an installation has 12 strings doesn't mean that fuses are nescessary. It depends upon how they are JOINED.

If you have say an SMA 17000TL which can take 5 strings in on MPP input A and 1 string on MPP input B, if you have a TOTAL of 4 strings, 3 on MPP A and one on MPP B you do NOT need string fuses - each MPP is an 'Array'. If you had 5 strings, 4 in MPP A and one in MPP B you WOULD need string fuses.

String fuses are NOT a short circuit protection, as short ciruit current is close to operating current, they are to protect for a fault condition when one string ends up powering another, so putting more current through the panels than expoected under normal operating conditions, bearing in mind that the string fuse must have a tripping current which is less than 2 x Isc (stc) and the string cable current carrying capability, whichever is the lower value, also remeber that they should be rated for a voltage of Voc(stc) x M x 1.15 wher M is the # of panels in the string.

Over and above that, for some modules, the reverse current rating provided by the manufacturer MAY permit more than three parallel connected strings to be installed without string fuses. In such cases, the number of strings that may be connected in parallel without the use of fuses is calculated by ensuring: Ir > I (stc) x (N-1) x 1.25 where Ir is the maximum permitted reverse current quoted by the module (N is the # of strings)

An ARRAY is a series of strings connected in parralllel - in the case of string inverters that usually means to the same MPP, in the case of central inverters, which don't have individual MPP's it usually relates to whatever is connected to that Inverter - could easily be 100 strings.

 

[Worcester]

@woko which inverter are you using - the power-one 20kW? If you are using the S2X version, it comes with string fuses pre-installed, and has 4 pairs of MC4's for each MPP, if you are using the BASIC and S2 version it has one pair of screw connectors per MPP so if you have 4 or more strings per MPP on thise versions you WILL NEED string fuses. - Most suppliers ship the S2X version in the UK - you need to check though.

 

[Gavin A]

String fuses are to stop one string overpowering another with reverse flow.

Also just becasue an installation has 12 strings doesn't mean that fuses are nescessary. It depends upon how they are JOINED.

If you have say an SMA 17000TL which can take 5 strings in on MPP input A and 1 string on MPP input B, if you have a TOTAL of 4 strings, 3 on MPP A and one on MPP B you do NOT need string fuses - each MPP is an 'Array'. If you had 5 strings, 4 in MPP A and one in MPP B you WOULD need string fuses.

String fuses are NOT a short circuit protection, as short ciruit current is close to operating current, they are to protect for a fault condition when one string ends up powering another, so putting more current through the panels than expoected under normal operating conditions, bearing in mind that the string fuse must have a tripping current which is less than 2 x Isc (stc) and the string cable current carrying capability, whichever is the lower value, also remeber that they should be rated for a voltage of Voc(stc) x M x 1.15 wher M is the # of panels in the string.

Over and above that, for some modules, the reverse current rating provided by the manufacturer MAY permit more than three parallel connected strings to be installed without string fuses. In such cases, the number of strings that may be connected in parallel without the use of fuses is calculated by ensuring: Ir > I (stc) x (N-1) x 1.25 where Ir is the maximum permitted reverse current quoted by the module (N is the # of strings)

An ARRAY is a series of strings connected in parralllel - in the case of string inverters that usually means to the same MPP, in the case of central inverters, which don't have individual MPP's it usually relates to whatever is connected to that Inverter - could easily be 100 strings.

thanks - that was pretty much what we decided as well after thinking it through for a bit.

I can imagine a jobsworth MCS assessor / building regs might take a different view though, so I'm hoping it's clarified in the new guide (if it ever gets published).

 

[sedgy34]

Cheapest course sounds the best to me

 

[SolarCity]

I doubt a G59 course would be much benefit to most people on here for reasons that have been posted. Larger scale installs will still require relay protection but you're far better off speaking to someone like Andy O'Leary at Sibert for things like that. I doubt that you'd get this kind of thing covered on a £200 course anyway.

As always, most of the questions you would probably have could be answered on these forums anyway.

 

[JD6400]

I attended one of the afore mentioned training centres on the second or third time they had held a G59 course and with a couple of other installers ended up helping the instructor with his knowledge !:cowboy:

Should have known really as the same had happened with our initial PV and wind courses with them , but you live and learn .:skep:

 

[SpitfireW'sale]

Anybody attended one? Eco skies want 400 plus for a days course but I've found other training places that only want 225 plus.
Are they worth doing?
I'd like to learn about the application process and the G59 relays.

I know of several installers who have shelled out for "G59" courses having been told by their training centre that it is a requirement for them to do so before they can install anything above 4kW.