Solar Panel Install - Testing

[waitees]

Hi all

I have been approached by a friend of a friend to get involved with certifcating solar panel installs. The company have just got there mcs etc and are all up and running but have asked me to get a little involved and to issue a certifcate.

I have checked with the NICEIC and they confirmed the paperwork etc and thats all sorted but my question is to do with the wiring ac side of things.

They have run 4mm 3 core swa cable as it goes outside and they have not earthed the swa cable which goes into the last ac switch and then from there into normal 4mm twin and earth cable into the meter and then from the meter into a 16a mcb again in 4mm t&e connected to a one way board with 25mm meter tails out of the main switch into a henley block.

This is all new to me however if this takes off and is constant work, i will do the pv course just so i know the ins and outs.

Could someone point me in the right direction what size cable etc i should be checking from the last ac switch to the meter and from the meter to the board set up as this dont look right ?

Cheers

Paul

 

[Markc]

First of all the 4mm SWA outside should have the armoured earthed. But you know that. The size of this cable should be calculated at no more than a 1% voltdrop. The AC cable coming in from the PV array through a AC isolator again is all OK. From that into a generation meter (Load side being the property NOT the array) into a 16A MCB (I would also see a need for 30mA protection as by the read if it the inverter is outside? Discussions on the exact position of the gen meter i.e. before or after the final AC isolator rage on but as far as I see it, it makes little difference. The cable size should be the same though out for VD so dependant on length then 4mm all the way is OK.

 

[waitees]

hello Marc

Thanks for the reply, the inverter is inside the loft space and looks all correct with another ac switch. The inverter is a Sunnyboy this has not been put on a rcd but has paperwork with it and said that it has a glav earth inside with no need, should i recomend a rcd as well or there really is no need.

cheers Paul

 

[Markc]

hello Marc

Thanks for the reply, the inverter is inside the loft space and looks all correct with another ac switch. The inverter is a Sunnyboy this has not been put on a rcd but has paperwork with it and said that it has a glav earth inside with no need, should i recomend a rcd as well or there really is no need.

cheers Paul

There is no need unless the inverter is in a special location. I assumed it was outside from the original post (don't really know why now I have read it again?)

 

[waitees]

Cheers for the help Marc

 

[lother]

Hi guys iv been approached to do solar pv but i have no previous experience. iv got my 17th edition 2391 etc. how would i go about connecting them up and also what testing procedure would i need to do?


Thanks

 

[TedM]

Read the DTI PV Guide. Its a sticky - http://www.electriciansforums.net/photovoltaic-solar-panels-green-energy-forum/23511-pv-guide.html

 

[lother]

Thanks where about in carmarthenshire u from im from same area

 

[GaryM]

I'd recommend you sit the C&G2399 course if you want to go down the PV route.

 

[lother]

so would i need to do a full inspection and testing on the other circuits already installed or only the cable i install from the inverter. would i need to do ze, pfc, etc.

 

[lother]

I'd recommend you sit the C&G2399 course if you want to go down the PV route.

ye have been looking into it just wanted to know brfore doing course

 

[yellowvanman]

so would i need to do a full inspection and testing on the other circuits already installed or only the cable i install from the inverter. would i need to do ze, pfc, etc.

Treat it like any other new circuit - you only test what you have done and making sure earthing and bonding is up to scratch. Then test and fill in an EIC.

 

[jazzygazza]

the solar pv course goes through the installation, which is useful for what you need to know on subject , however doesnt go through the testing side of it though, just as long as you know how to fill out EIC form then just fill out as normal with minor changes to normal inspection

 

[GaryM]

The C&G2399 I attended included testing of the AC and DC sides.

 

[lother]

The C&G2399 I attended included testing of the AC and DC sides.

what test do u do on them. would it be a minor works certificate or an electrical installation

 

[GaryM]

EIC as its a new circuit. Nothing more than I'd normally do when completing an EIC.

 

[lother]

whats mcs accreditation do i get this by doin the c&g2399

 

[yellowvanman]

whats mcs accreditation do i get this by doin the c&g2399

None - it just shows you have a level of competance when you apply and get assessed for MCS

 

[Mkukorlo]

I'm sorry if this is the wrong thread but I'm not sure how to use this yet and the banner on top is instructing me I need 6 replies to gain full access. So my first question is how do I start a thread and not step on other people. Secondly, is there an inverter with 2 inputs (one being DC from the PV and the other AC from the grid) and one output (AC) to power a load. The concept is an inverter to power a single load such as a heavy freezer. The device would need to use the PV power "first" and supplement the additional power needed from the grid. This inverter does not feed back into the grid. Thank you for any help and apologize if this is stepping on the thread.

 

[Worcester]

Here will do

OK, so let me see if I've got this right,
1) The inverter MUST NOT FEED INTO THE GRID - is that a requirement or a desire?
2) You want the load (freezer, variable power consumption, inductive load) to use whatever output is generated from the Inverter 'as a priority' and if insufficient (not enough) power from the Inverter to supplement it from the grid.
3) If the Inverter is generating more power than the load (freezer) needs, then to restrict the output of the inverter so that it doesn't feed back into the grid.

The most important part is your answer to question 1) - a legal / electricity supply company REQUIREMENT - or just your desire?

 

[Mkukorlo]

Thank you for the quick reply.
1) That is correct; the inverter must not feed back into the grid. This would be a legal requirement. The idea is to off-set a hungry continuous load such as a heavy freezer with PV panels that even at their best, would only supply 50% of the required load. Real-estate for the panels and the cost for permits, disconnects, subpanels, inspection, etc. is the underlying issue here.
2) Yes, the DC input would need to be the priority channel such that the inverter utilizes the solar energy first and then supplements the additional power needed from the grid.
3) Correct again. In the unlikely event two of the three compressors fail and the PV is producing more power than the load requires the inverter would need to restrict the load and prevent flow back.
I am currently a journeyman with my expertise being diesel and GTC generators. Solar technology is still very new to me. I greatly appreciate any additional help.

 

[Worcester]

OK... SMA have a series of technical documents Information and details regarding the self-consumption of solar energy and Overview of the grid management functions of SMA inverters

Howver you are going to need a custom switching solution.

The 'cheap way' is by using a dump load, (heat up a load of water) using an Immersun type device Technical Resources | Micro-Generation Power Manager, this will monitor import and export and divert all excess generation to a resitive load. The standard immersun can divert up to 3kW, they can be daisy chained for greater power, and will work with any inverter

The alternative is a custom interface to the SMA Power Reducer Box POWER REDUCER BOX

What size PV plant (kWp) are you considering?

 

[Mkukorlo]

You are fast!! kwp= 2200watts

 

[Worcester]

@ 2.2kW the I'd use the Immersun and heat a great big tub of water - are you at 220-240Volts there? or is the NJ = New Jersey?

or send it to a 'proper' dump load via the Immersun
http://www.altestore.com/store/Char...ric-2000-W-Dump-Load-ResistorAdj-18-Ohm/p686/

 

[Mkukorlo]

We are 220. Yes, New Jersey. South Jersey though. Not anywhere close to the fools on Jersey Shore,
they really are embarrassing to the State When you say a custom switching solution do you mean a way to choose the priority of what channel the load is deriving the power from because they will need to be "mixed". Or are there inverters available with 2 inputs and 1 output and the switching solution is in relation to diverting the extra current, in case of equipment failure, into the dump load.

 

[Mkukorlo]

I'm trying not to be over grateful but thanks again for the time you’re taking out of your day to help!

 

[Worcester]

220V no question, go for the Immersun and dump load, see the technical download, it manages the switching to the dump load to prevent export - it does it propotionally by monitoring the grid for import / export so if you are generating 2kW and using 1kW it will send 1 kW to the dump load, if you were using 1.5kW it would send 0.5kW to the dunp load - that is why it needs to be a resistive load.

The immersun will provide you with your 'custom' switching solution, it can be configured in a number of diffient ways - dowload the manual from the above link and it will all makes sense

Dump loads are commonly used on Wind Turbine systems as there is no way to scale down their output power and they are often used in 'off grid' situations where sometimes no power is being consumed, so it has to be dumped.

You're other options are a lot more expensive by a factor of 4 at least.

 

[Mkukorlo]

Thanks, I'll keep you posted.

 

[taffbutc]

MCS are changing the guidance as well where you will have to have certain qualifications. I will try and find it.