Solar Pv Spd.

[gselectrical]

Good morning all. 

We have been asked to install some Surge Protection Devices on a Solar PV system. 

I thought I would check what we propose to do with you guys as we do not install PV systems and have little experience in that area.

The PV system is supplied from a 3 phase board (L1 phase)

We are going to fit a 240v SPD within the consumer unit supplying the PV system (on L1 phase).

We are then going to fit a DC SPD as close to the inverter as possible. (The distance of the PV leads from the inverter to the panels is less than 10m, so I believe one DC SPD will be ok)

There are 3 strings and 3 isolators for the panels. Does each string have to be connected to the SPD individually? 

I was planning on running 6mm from inside the inverter to the SPD (There is a set of spare connections inside on the + and -) Clearly all 3 strings terminate at the same point within the inverter so should this be ok?

I believe we would need some sort of fuse in the + line connecting the inverter to the SPD? Can anybody recommend something suitable?

As always any advice greatly appreciated.

GS

 

[steptoe]

do you have your PV qualifications?

if not, then you are NOT allowed to touch or modify any part of the PV installation as you will have to sign that it is all compliant with the relevant regs.

 

[Sidewinder]

Not just quals Steps, GS, you will have to ensure & certify that the system once completed complies with the requirements to receive or, keep the FITS that apply if relevant, & TBH I doubt that there is much Solar that is not FIT registered?

IF, when you complete it the install does not meet the requirements to receive the FIT, then, if the tariff is claimed & received, then this could well be classed as fraud, as someone could be claiming something that they are not legally entitled to, and, another could have stated that something is entitled to receive the FIT when it is not!...

 

[steptoe]

Not just quals Steps, GS, you will have to ensure & certify that the system once completed complies with the requirements to receive or, keep the FITS that apply if relevant, & TBH I doubt that there is much Solar that is not FIT registered?

IF, when you complete it the install does not meet the requirements to receive the FIT, then, if the tariff is claimed & received, then this could well be classed as fraud, as someone could be claiming something that they are not legally entitled to, and, another could have stated that something is entitled to receive the FIT when it is not!...

quite,

that is what I was meaning to mean to comply with MCS.

 

[gselectrical]

Ok, Cheers guys. 

We are not MCS registered, so I will liaise with another contractor we often work alongside, who is MCS registered to carry out the work. 

The premises is a commercial building, so not sure if the FIT's apply? Sorry, I have very little experience when it comes to PV, although it is something we may be looking into in the future (When people start paying their bills and funds become available!!)

Does what I have proposed in my original post sound ok?

The MCS registered contractor we use has not fitted any SPD's in the past, so I could do with a bit of advice & guidance. 

Cheers

GS

 

[steptoe]

your MCS accredited contractor would need to look at the install and work out what would be compliant and compatible with the type of inverter fitted.

 

[Sidewinder]

Etc., etc.

 

[Chewbacca]

commercial systems qualify for FITs, TBH AC side is fairly irrelevent once fitted. I can't think of any legal reasons to prevent you working on the AC apart from the usual competence etc etc.  DC side is another matter. Commercial systems frequently work on 800V DC due to large strings of panels - nasty stuff! Some inverters can have DC fuses fitted, can't see SPD being any use on DC. The AC side is where I would be looking to fit such devices, before the inverter, to prevent grid spikes damaging the inverter itself.

 

[gselectrical]

Cheers for all the replys. 

What make of inverter is it ?

Its a sunnyboy. Small system. 4kW.

commercial systems qualify for FITs, TBH AC side is fairly irrelevent once fitted. I can't think of any legal reasons to prevent you working on the AC apart from the usual competence etc etc.  DC side is another matter. Commercial systems frequently work on 800V DC due to large strings of panels - nasty stuff! Some inverters can have DC fuses fitted, can't see SPD being any use on DC. The AC side is where I would be looking to fit such devices, before the inverter, to prevent grid spikes damaging the inverter itself.

Iv'e been looking into Furse' technical reference documents which state that an SPD should be fitted on both the AC and DC sides of the PV system (assuming the DC is required to protect the inverter from partial lightning strikes). The AC side is not an issue. As we will not be altering any part of the PV system, the SPD will be in parallel. 

Cheers. 

GS

 

[gselectrical]

Some of the SMA's can have SPD's fitted as an optional extra (DC Side), these are just plug in modules depending on the Inverter this may be possible

For the AC side i would fit

http://www.abb.co.uk/product/seitp329/2359d69bf7eaa242c1256ef40023ef7e.aspx

I will try and contact the firm that originally installed the kit, perhaps they would know whether an SPD is part of the inverter. 

Regarding the AC, that's what we plan to fit but we will use Furse kit as that is what has been spec'd. 

Cheers

GS

 

[Chewbacca]

contact SMA direct, their technical helpline is excellent.