Surge arrester before or after fuse?

I've got my new 22 panel array up (2 x 11 250W Solarworld Mono Black panels per string). Now doing the wiring... great weather for it... cold and rainy.

Will post pictures later.

Are you referring to a PV surge arrester? I put it after the fuses, so hopefully the fuses will blow first, they're cheaper.

Thx, Silver. That logic works for me also.

 

Yes, we try to avoid damages on surge, stopping current thtough surge, blowing fuse.

 

Fuses aside.

I will supplement this discussion by adding that a ferrite bead ( look them up on google), should be attached on both the +ve and -ve PV leg on the equipment side just after the surge arrestors.  This bead will act like the end of a bathtub for a travelling wave and present your surge arrestors with a localized voltage spike giving them a reason time to do their job.

 

Read up on Transil  diodes or TVS diodes they are also called.

They are cheap enough, and are much faster than conventional surge arrestors. ( Get a suitable rating for your system and connect between +ve and -ve to earth, you can also connect one between +ve and -ve as well). I think 1nS response time as compared to 100nS if I remember right.

A fuse blows because of excessive current, in other words there has already been an insulation breakdown caused by the incoming voltage spike.

In short, you want to give the voltage somewhere to break down the insulation, (that isn't inside your expensive equipment), and if the surge arrestor doesn't self-seal then  rely on a fuse to blow.  A ferrite bead and transil diode is probably your best chance of creating a very fast acting weak point.

Costs are insignificant compared to your MPPT(s).

Edited December 29, 20187 yr by phil.g00

OK, that's a lot to think about.

I believe it is absolutely worth the effort. The beads and the diodes will be added to all 3 strings within the next few weeks.

Just trying to locate supply of DC cabling yesterday was a challenge... I'm probably going to be about 5m short on one of my strings... dammit!

PPPPPPP.

10 hours ago, phil.g00 said:

Read up on Transil  diodes or TVS diodes they are also called.

They are cheap enough, and are much faster than conventional surge arrestors. ( Get a suitable rating for your system and connect between +ve and -ve to earth, you can also connect one between +ve and -ve as well). I think 1nS response time as compared to 100nS if I remember right.

A fuse blows because of excessive current, in other words there has already been an insulation breakdown caused by the incoming voltage spike.

In short, you want to give the voltage somewhere to break down the insulation, (that isn't inside your expensive equipment), and if the surge arrestor doesn't self-seal then  rely on a fuse to blow.  A ferrite bead and transil diode is probably your best chance of creating a very fast acting weak point.

Costs are insignificant compared to your MPPT(s).

This is indeed an interesting approach yet none of the suppliers I know use TVS diodes in their PV fuse boxes

1 hour ago, SilverNodashi said:

This is indeed an interesting approach yet none of the suppliers I know use TVS diodes in their PV fuse boxes

I didn’t install any panels yet.

Steve

11 hours ago, Elbow said:

This is indeed an interesting approach yet none of the suppliers I know use TVS diodes in their PV fuse boxes

They are being adopted in inter-building RJ45 termination boxes, (without the bead, as that would affect the high frequencies).

Solar panels being DC don't have that limitation, so use a bead.

Yes, you are right, the diodes seem to be a recent phenomenon.

This patent is full of legal jargon, but it looks it might be the actual patent application:

https://patents.google.com/patent/US8338854

The application has a 2009 date.

If that's the case, well then yes they are an extremely recent phenomenon.

Also while I was doing a bit of googling myself, I saw Wikipedia make the claim of 1 picosecond response time.

I just cant see that happening, light will only travel about 1/3 of a millimeter in a picosecond.

 

 

 

12 hours ago, Elbow said:

I didn’t install any panels yet.

Huh? Sorry, posted in the wrong thread

20 hours ago, PaulinNorthcliff said:

Just trying to locate supply of DC cabling yesterday was a challenge... I'm probably going to be about 5m short on one of my strings... dammit!

I know the frustration of being caught short when everything is closed (this is the only time we get to work on our home systems 😏). If you want to pop out to Centurion I can help you out with some PV cable...

On 2018/12/29 at 10:59 AM, PaulinNorthcliff said:

Surge arrester before or after fuse?

I've got my new 22 panel array up (2 x 11 250W Solarworld Mono Black panels per string). Now doing the wiring... great weather for it... cold and rainy.

Will post pictures later.

Don't worry there is never a silly question on this forum. It is part of the forums ethos.

Sincerely

Jason

Thanks, guys. I sorted all my issues... both surge arrestor and cabling.

Even with the rather dismal (overcast/rainy) skies over Joburg the last few days I am happily over-producing by more than 20KW per day. I reckon clear skies will push this up to 30KW.

End of this month I will add two more 2.4KW Pylons, and a new cabinet for (eventually) four 3.5KW Pylons to go in parallel with the (then) four 2.4s. Then I reckon my power is sorted for a bit... uh... then onto the office... an entirely new installation and challenge.

I should mention that I am busy building a 'show container' for the NPC I run. A 6m shipping container equipped as a show stand to transport around the country. I am building a 2KW solar system into the container. Six Canadian Solar 330W panels fixed flat on top, an Axpert 5Kva invertor and two 2.4KW Pylons. I hope to finish that this weekend. It should be totally self-powered, but I have the facility to 'grid-tie' it to a power source or genny should the need arise. The container has aircon, lights and plugs (for fridge, coffee machine, etc) inside.

I'll post a separate thread about the container... for interest sake.

4 hours ago, PaulinNorthcliff said:

I'll post a separate thread about the container... for interest sake.

Look forward to it

7 hours ago, PaulinNorthcliff said:

but I have the facility to 'grid-tie' it to a power source or genny should the need arise.

This is a great use of containers and solar, but for the love of solar, don`t use grid-tie and Axpert in the same conversation.  :-)

 

17 minutes ago, anotherbrownbear said:

This is a great use of containers and solar, but for the love of solar, don`t use grid-tie and Axpert in the same conversation.  🙂

 

🤣

16 minutes ago, anotherbrownbear said:

... , but for the love of solar, don`t use grid-tie and Axpert in the same conversation.  :-)

Give that man a Bell's! 

Go Blue or go White ... 

Otherwise the container houses are freaking awesome! Well Done!

On 2019/01/09 at 10:16 AM, anotherbrownbear said:

...don`t use grid-tie and Axpert in the same conversation.  🙂

This makes me sad.

Why not? They seem rather 'not too critically thought of'...

Look, grid-tie will be only on the odd occasion. 99% of the time the container will have no connection (nor need one). My 'grid-tie' will mostly be a small genny for IF we have to supplement the panels for some reason.

 

 

... because an Axpert cannot “grid-tie”. Grid tie means to operate in parallel with the grid, i.e. the inverter can import and export power. An Axpert cannot export power.

I think what you mean to say is “grid-connected”. If you use that terminology, all flack will cease 🤓.

28 minutes ago, Power Punk said:

I think what you mean to say is “grid-connected”. If you use that terminology, all flack will cease 🤓.

Yeah but people also use "off-grid" for things that can be grid-connected. Technically it is only properly off-grid if it has no AC-input. Like the Victron Phoenix inverters for example.

1 minute ago, plonkster said:

... no AC-input.

Like all Axperts are now forced to be ... (cwl) (sorry, I could not resist.)

I'm sorry and I know I keep hammering on this but until someone coughs up a document stating that it complies either to Nersa as a grid connected inverter or to SANS as a solar assisted UPS, it should be deemed an off grid inverter.

2 hours ago, Power Punk said:

... because an Axpert cannot “grid-tie”. Grid tie means to operate in parallel with the grid, i.e. the inverter can import and export power. An Axpert cannot export power.

I think what you mean to say is “grid-connected”. If you use that terminology, all flack will cease 🤓.

Ah!

Right you are. <mutters... "bloody anoraks!">