PV External inverter installation

[Marvin]

Am I done?

[SteamyTea]

44 minutes ago, Marvin said:

Am I done?

Dunno, see what happens when it gets dark.

[Marvin]

Forgot to stick on labels.....

[Marvin]

Am I done?

 

 

[PeterW]

What stops water getting into the end of these ..?? 
 

[ProDave]

I am not even convinced that inverter is okay for outside mounting?

[TonyT]

9 minutes ago, ProDave said:

I am not even convinced that inverter is okay for outside mounting?

Think they are IP65 so no issues there.

 

[TonyT]

Apart from being untidy, my only issue would be the 2 strings passing through the one DC isolator, but that’s a personal thing probably couldn’t find a specific regulation

 

if all 3 isolators were side by side it would be an easier installation to maintain.

[Bramco]

1 hour ago, TonyT said:

 

if all 3 isolators were side by side it would be an easier installation to maintain

 

How?

 

I'm genuinely curious - how does the positioning of the isolators impact ease of maintenance? 

 

Simon

[TonyT]

It’s a 2 string inverter, with 2 strings passing through the top isolator.

poor for a new installation as far as I’m concerned.

 

if each isolator was side by side, Dc PV cable could enter via the top and exit via the bottom. Each string would be seperate.

AC isolator adjacent to it, it would have looked like someone thought about the installation.

Edited December 15, 2021 by TonyT

[mrbd]

You seem to have two DC isolators in series on each string? Be careful because although a DC isolator might have 4 poles, the internal links need to remain and are there by design to break the DC arc. I suspect that it should be 1 dedicated DC isolator per string. Can you share the wiring diagram /SLD from the electrical design? Or better still a photo of the inside wiring of the DC isolators with the covers off? I'm concerned that if you operate a DC isolator under high irradiance it could risk a fire.

[Marvin]

17 hours ago, PeterW said:

What stops water getting into the end of these ..?? 
 

Gravity?

[Marvin]

16 hours ago, ProDave said:

I am not even convinced that inverter is okay for outside mounting?

[Marvin]

5 hours ago, mrbd said:

You seem to have two DC isolators in series on each string? Be careful because although a DC isolator might have 4 poles, the internal links need to remain and are there by design to break the DC arc. I suspect that it should be 1 dedicated DC isolator per string. Can you share the wiring diagram /SLD from the electrical design? Or better still a photo of the inside wiring of the DC isolators with the covers off? I'm concerned that if you operate a DC isolator under high irradiance it could risk a fire.

Hi @mrbd Yes it looks worse than it is. The top DC isolator isolates string one only and the lower one isolates string 2 only.

 

Here's the mathematics. The percentages are related to the inverter maximums:

 

Set up	Quant	Watts
Longi 320 watt panel	1	320	Watts
amount of panels	16	5,120	Watts	85%
Inverter Max	1	6,000	Watts
					DC         isolator        max     amperage
String wattages
String 1	7	2,240	Watts	56%	7.84
String 2 panels	9	2,880	Watts	72%	7.84
Maximum string		4,000	Watts
Panel voltage	panels	41	Volts
String 1 panels	7	286	Volts	48%
String 2 panels	9	367	Volts	61%
Maximum string Voltage		600	Volts

 

 

 

 

[Marvin]

14 hours ago, TonyT said:

It’s a 2 string inverter, with 2 strings passing through the top isolator.

poor for a new installation as far as I’m concerned.

 

if each isolator was side by side, Dc PV cable could enter via the top and exit via the bottom. Each string would be separate.

AC isolator adjacent to it, it would have looked like someone thought about the installation.

 

Yes, perhaps proper function but form needs improvement.  

[SteamyTea]

As you have a 5.1 kW system, why did you go for a 6 kW inverter?

Or is that the very maximum it can take, rather than the nominal value?

[Marvin]

3 minutes ago, SteamyTea said:

As you have a 5.1 kW system, why did you go for a 6 kW inverter?

Or is that the very maximum it can take, rather than the nominal value?

Yes the maximum the inverter will take.

 

It also allows room for me to fix extra panels to the chimney..

 

 

Edited December 16, 2021 by Marvin

[SteamyTea]

2 minutes ago, Marvin said:

Yes the maximum the inverter will take.

Right.

 

Just as a general note:

6 hours ago, mrbd said:

I'm concerned that if you operate a DC isolator under high irradiance it could risk a fire.

Always switch the AC side off first to isolate the load from the modules, then the DC side.

Edited December 16, 2021 by SteamyTea

[Marvin]

3 minutes ago, SteamyTea said:

Right.

 

Just as a general note:

Always switch the AC side off first to isolate the load from the modules, then the DC side.

I think I will label that up to remind me. Its always months/ years later that you come back to do something...

[SteamyTea]

3 minutes ago, Marvin said:

I think I will label that up to remind me. Its always months/ years later that you come back to do something...

I think you have to notify the DNO about the location of the isolators as well.

[Marvin]

10 minutes ago, SteamyTea said:

I think you have to notify the DNO about the location of the isolators as well.

Yes, they are due round. Paid my £360 for that. Positions of isolators as submitted in application....

[Ronski]

On 16/12/2021 at 02:27, mrbd said:

You seem to have two DC isolators in series on each string? Be careful because although a DC isolator might have 4 poles, the internal links need to remain and are there by design to break the DC arc. I suspect that it should be 1 dedicated DC isolator per string. Can you share the wiring diagram /SLD from the electrical design? Or better still a photo of the inside wiring of the DC isolators with the covers off? I'm concerned that if you operate a DC isolator under high irradiance it could risk a fire.

 

I've got a 12 panel array, as per picture below. this will be wired up as 2P3S (if I've got the terminology correct), so each 3 panels facing west will be a series string, then those two strings paralleled up in an internal combiner box with individual fuses for each 3 panels and DC MCB. Same for the two east facing strings.

 

 

My electrician says I need to fit a DC isolator for each string, so will that be four DC isolators? Was thinking I could use two 4 pole isolators but given the quote above, it seems not.

 

Are they supposed to be externally fitted or is internally in the garage acceptable.

 

I will check with the electrician, but it can take him days to reply, and unless I get lucky he doesn't answer the phone.

 

 

[SteamyTea]

The isolators can be in the garage, as long as they are easily accessible.

 

If I understand your wiring correctly, you will be dealing with the voltage from, in effect, 3 panels, does your inverter work efficiency at reduced voltage?

[Ronski]

@SteamyTeaThanks, but do I need two isolators or four? I'm thinking four, if installed between the panels and the solar combiner boxes, or two if between combiner and MPPT.

 

I'm using a 48v Victron system, SCC will be two SmartSolar MPPT 150/45.

 

 

[SteamyTea]

9 minutes ago, Ronski said:

but do I need two isolators or four

Four I think, but not absolutely sure.

The idea of isolators is that you can work on a system safely i.e. change a fuse without the risk of a live wire giving you a shock.