Goo day

 

So after seeing the "professionals" do a few of our installations, I thought I can do it just as well or better for cheaper.

Yes I know that I will still need a COC, I will do most of the work myself and then get a professional to go through everything and do a COC.

 

It will be 3 strings of panels, each double fuseholder will kill the + and - of each string.

are the way that I've bridged them on top correct ?

 

tia

So you are going to feed the fuses from the bottom? Best practice is to feed everything from the top. I will also feed the surge from the panels directly on not through the fuses.

Feeding the fuses from the bottom means they could be "hot" when you pull them...

P1000 is correct. Feeding from the bottom you cant touch or replace fuses without the risk of being shocked.

Mine is done like this . electrician said its correct.

 

Are these cheap Chinese SPD's and breakers any good? 

This is a very interesting topic...So you have 2 strings of PV & 2 MPPTs. How many T2 SPDs do you fit? One string goes into each MPPT.

13 minutes ago, Steve87 said:

This is a very interesting topic...So you have 2 strings of PV & 2 MPPTs. How many T2 SPDs do you fit? One string goes into each MPPT.

Each string should have it's own breaker and SPD unless they are parallel.

49 minutes ago, Steve87 said:

This is a very interesting topic...So you have 2 strings of PV & 2 MPPTs. How many T2 SPDs do you fit? One string goes into each MPPT.

Please expand on the 2 strings and 2 MPPT. I can  see 4 strings each to their own fuses. They are then combined and to circuit breaker and SPD. The outgoing circuit to the MPPT I see only 1 red and black exiting on the RHS bottom.

Basically 2 MPPTs & 1 string into each was my question. @Chris_Sgot the correct answer to this. You must match the SPD to protect each MPPT. 

Another misconception is where to place the SPD. Directly from the panels then via the fuses or after the fuses. Here is a diagram to argue over. Will have good discussion on this. In Gauteng we are especially prone to Surges & Lightning. 

Which one is best protection A or B. I believe there is no right or wrong answer. Only collective discussion. 

5 minutes ago, Steve87 said:

Basically 2 MPPTs & 1 string into each was my question. @Chris_Sgot the correct answer to this. You must match the SPD to protect each MPPT. 

Another misconception is where to place the SPD. Directly from the panels then via the fuses or after the fuses. Here is a diagram to argue over. Will have good discussion on this. In Gauteng we are especially prone to Surges & Lightning. 

Which one is best protection A or B. I believe there is no right or wrong answer. Only collective discussion. 

I would say circuit A. You still want protect even if the breaker is off. 

I think the way to best help make understanding of this is: What are we protecting with the SPDs.? The inverter or the Panels? 

2 minutes ago, Steve87 said:

I think the way to best help make understanding of this is: What are we protecting with the SPDs.? The inverter or the Panels? 

SPD's protect inverters. Fuses protect shorts or overcurrent from panels or wires. 

Steve while on this subject. I want to use Citel SPD's. Rubicon are out of stock of the 600vdc version. My strings max voltage will be 400V. You think I could use a 500VDC 40kA type 2 version SPD? 

3 minutes ago, Chris_S said:

SPD's protect inverters. Fuses protect shorts or overcurrent from panels or wires. 

To me both A & B are within stream in series with the circuit & Wil both protect the inverter. However, Citel & most other SPD manufacturers say that B is most correct. They say that with either fuse popped the inverters have the SPD protection in tact. 

Anyhow, I guess it like investing something is better than nothing 🤣🤣🤣

6 minutes ago, Chris_S said:

Steve while on this subject. I want to use Citel SPD's. Rubicon are out of stock of the 600vdc version. My strings max voltage will be 400V. You think I could use a 500VDC 40kA type 2 version SPD? 

As long as your string voltage is below the Surge arrest voltage & it's T2 I don't see any issue. For sure some will say that the threshold voltage gap is only 100V is too small. However, my thinking is 100V is substantial. If that type of Voltage has mustered into the circuit there is definitely some mischief taking place on the circuit. 

In my book it's a winner. 600V is 1st prize. But if 500V is all you got I'd go for it. 

 

We supply over 1000 PSUs monthly. The range is in the sub 5A category. All our designs for surge proofing is B.

My question is why would you want to clamp a strike at say 600V if A is used when the MPPT can only withstand a say 145/400V?

How would the SPD protect the panels?

Although A can be used I have never seen PSUs designed as such.

Edited December 2, 20223 yr by Scorp007

4 minutes ago, Scorp007 said:

We supply over 1000 PSUs monthly. The range is in the sub 5A category. All our designs for surge proofing is B.

My question is why would you want to clamp a strike at say 600V if A is used when the MPPT can only withstand a say 145/400V?

Although A can be used I have never seen PSUs designed as such.

If the breaker in B is closed then it doesn't really matter. The spd is still in parallel to the panels

2 minutes ago, Chris_S said:

If the breaker in B is closed then it doesn't really matter. The spd is still in parallel to the panels

Point taken but normally the breaker will not stay closed during a direct strike when B is used.

3 hours ago, Steve87 said:

Basically 2 MPPTs & 1 string into each was my question. @Chris_Sgot the correct answer to this. You must match the SPD to protect each MPPT. 

Another misconception is where to place the SPD. Directly from the panels then via the fuses or after the fuses. Here is a diagram to argue over. Will have good discussion on this. In Gauteng we are especially prone to Surges & Lightning. 

Which one is best protection A or B. I believe there is no right or wrong answer. Only collective discussion. 

I use a variation of Circuit B. Sunsynk 8.8 kW MPPT's max Voltage is 500V, therefor First double pole DC 500V trip. Followed by 2x fuses and 500V SPD per string. Inverter feed is taken from SPD's + -, not trip or fuses. (try and allow the wiring to inverter, to be longer than SPD's earth wire to ground, so that if the SPD's fire, the spike voltage will be pulled to ground before reaching the inverter)

I use 500V trip and 500V SPD's, as I don't want to see or smell the blue smoke of unhappiness rise from my inverter. 😂

The main reason the double pole trip is first, is that when home, and there is lightning storms, I disconnect the solar, and therefor save the entire string setup including the SPD's from unnecessary damage.

The SPD mounted at the inverter is designed to protect the inverter, and the appliances connected to the inverter, from surges and transient voltages that come from the solar panels or induced into the DC cables between the panels and inverter, therefore B is correct because the SPD permanently connected to the inverter whether the breaker/isolator is up or down. 

The only time your panels are at risk of surges is if your DC cables are longer than 10m. Long cables can get voltages induced into them by nearby lightning strikes and other crazy stuff. If your DC cables are longer than 10m then you should be placing an SPD near the inverter and another near your panels. The SPD at your inverter will not protect your panels. 

On my breaker its wired as in pic.

The drawing on the pic circled says it should be different.

with the outlet at bottom having the polarity swapped. 

this does not make sense to me unless its wired in series.

Cant seem to find the reason or correct info.

This is what you call poor Quality Control. I remember a few years back a few Noarks that had the same issue. Bottom line, you need to know what you are doing otherwise some labelling will take you somewhere you have never been 😣

No, the labeling is correct. You have to think about potential difference. Think of when the left only switch is open, right connected, the top of the left switch should measure negative with regards to the bottom. That is because to break the arc, magnets have to direct the arc away from the contact, if the voltage across the switch is reversed, the magnet will do the opposite...

Edited December 5, 20223 yr by P1000

Correct for some but not for others. I will stop you in your sentence when you say " you have to think". Sorry to say that the labelling convention here is not typical & most electricians won't make that mistake but many a person who is not exposed to DC circuits might end up with an interesting situation. 

Funnily enough in the Noark breakers someone mentioned the same thing. Sorry I'm just dumb & like things to be as easy as possible 😂😂😂

A work site has many distractions & ppl on it. The visual ambiguity here will lead many a person astray. 

Well, the proposed labeling will have people wiring it wrong and then it won't break the arc...

21 minutes ago, Steve87 said:

I will stop you in your sentence when you say " you have to think".

Yeah, I guess that is too much to ask.

Edited December 5, 20223 yr by P1000