schneider 100amp/600v charge controller in 24vdc

offgridcabin2015

I"m experts, 

I"m about to buy Schneider electric ( 865-1034) MPPT Charge controller  100a/ 600v. Will be running in  24vd.

i'm aware the input rang is  195-550vdc.

My current q cells open voc is 53.61 . Thus i want to confirm that i can install 7 panels   ( 53.61x 7 panels ) is 375.27volts ( in series)
Now the inverter says i can have up to 2 strings so i assume i just wire 3 panels in series for string 1 and same 4 panel in series for string 2?  Correct so far?

Now i realize this is considered high voltage and i want to go with / need din rail with high voltage breakers . Any have a drawing of me 
that i could follow for my install.  I never work with hi voltage before.  

I have attached all specs with pics. I"m always growing and learning. Thanks to you all. 

Neil.

Graham Parkinson

The Schneider HV Charge Controllers are actually single channel, they just have two common terminals to attach two strings.  So that means that both strings must be identical in number and type of panels.  It also means that they should preferably be similar in their orientations and time of sun exposure.

Based on just Voc, you could actually have 8 panels per string (ie. 428 Voc) but remember you need to check the temperature coefficient times the number of degrees that your location could drop down to from the Standard Test Condition (STC) temperature of 25 degrees C. 

Since most panels have a negative temperature coefficient, you can typically see about 10% higher Voc on a cold sunny day such as at say -10 degrees C.  So with 8 panels the maximum controller voltage would be approximately 428 V x 1.10 = 472 V, which is still a safe margin well below the max of 600V.

In terms of breakers, yes - the wisdom here from the forum is that an external 600 VDC disconnect is required, which could also be a breaker which are typically rated for about 1.6 * Isc (where Isc is the sum of the string currents).  You might get by with a single pole breaker but two pole breakers are probably a better choice.

offgridcabin2015

Ty so much for the reply @ Graham parkison, 
Wanted to get some clartiy on some statements.

i agree that  8 panels is the max but if ihad 2 strings of 8 that would put me over at (428x2) equalls 856volts.
I am also aware of the temp factor 1.25 ( for minus 40) in my canadian winters.

all my panels are the same , will be facing south as one unit/ array (np there)

So to keep under 600 volts. I could do wire one of two ways\
a) put 2 strings of 4 panels  (as you had mentioned the cc see it as one big string anyways right?) so best option.?

or

b) just one string of 8 panels?

Can someone show me a diagram i'm more of a visual person. This way i could follow it to the letter.

Also , what size din rail breakers would i need.(yes. double pole) i want both to shut off at one time) / code complient.

i'll buy on Amazon . 


I want to do this ONE time and SAFELY. Thankyou so much 

Graham Parkinson

No worries, the two strings go in parallel so you can have both without raising the voltage (in parallel only the currents add, not the voltage).  So you could have two strings of 8 panels and keep in your voltage target.

You want a PV disconnect (a switch rated to break the high voltage DC current) or a 2 pole breaker rrated for the highest voltage (ie 600V) and current carrying capacity of around 1.75 times the total current of the two strings (ie Isc of the panels times two).

Search for the Schneider Installers Manual, and the charge controller manual they have diagrams of how the charge controller and breakers should look like.

offgridcabin2015

Thankyou so MUch @ Graham parkinson , i feel i have a better understanding of this now. 
Let me run this by you .  , your saying: current carrying capacity of around 1.75 times the total current of the two strings (ie Isc of the panels times two).  so if one panel is 20 a (current) it's the same for one string of panels + another  20 for the 2nd array so 40a x 1.75 is 70am / 600v doubl pole breaker. correct?

Question. I think in reality now that i realize the parallel string thing (that's a lot of panels eeek) i could do 12 in total. ( 2 strings of 6)
but question is am i allowed to just put 8 panels on one string only and leave the other blank? or is is manitory that i fill the other bank too?
know what i mean?

Dave Angelini

There really are terminals for 3 strings inside and room for the fuses that we have to use for 3 strings. Schneider shows 2 strings because an inspector/installer would or should know that there is no need to OCP 2 strings. No prob with one string either. Be safe with this voltage and cover the array with a blanket or work early/late. Saying it again, BE SAFE !

offgridcabin2015

Thankyou Dave. Question what is OCP 2 strings?

Graham Parkinson

Over Current Protection - Not required if you only use one or two strings but required if you use three strings!

offgridcabin2015

Thankyou Graham, Good to know. 

offgridcabin2015

Hey gang do we ahave any picture of how to wire my 8 panels up the the MNPV8HV cominber / disconnect box?
I assume the 8 means 8 panels?

offgridcabin2015

now when i look at where the wire comes up, i see only 8 holes for 2 wires (that only  4 panels) right?   does this mean i need the  16 poistion for 8 panels.Or do i pull thru  4 wires per hole?  i'm so confused

littleharbor2

offgridcabin2015 said:

now when i look at where the wire comes up, i see only 8 holes for 2 wires (that only  4 panels) right?   does this mean i need the  16 poistion for 8 panels.Or do i pull thru  4 wires per hole?  i'm so confused

Generally speaking there would be higher voltage series wired strings going into each circuit

Dave Angelini

You are over thinking this and that is why you are confused

One of the best reasons to use the mppt-600 is to eliminate all of the balance of system components that just use your money and time up. The other reason is you can make alot more changes later when you use a 600 volt mppt.

 All you need is the Schneider / Square D disco (sold in the store here) and you are done. Design your panels for 2 strings or maybe one string if your temps do not get really cold and you are done.

offgridcabin2015

I need a picture of this setup plz Dave , ad dear old dad always said " a picture is worth a 1000 words" / This way i follow the install myself to the letter. I need to visualiz this.  I will be doing only one string of 8 panels (this year. ) next year . i'll do the exact same string of 8 more panels and paraellel em together to the one charge controller. 

Would anyone share a diagramof the wiring so i can see this . Then i buy what's needed. Thankyou. 

Dave Angelini

Call the store here and they may be of help. That is the end of my general advice. Good Luck and yes you can contact my email below.  I can offer you a year of support. I am in business for specific advice.

Graham Parkinson

What folks are saying is that with the high voltage controller, you don’t need a combiner box. Each of the panels that make up a string are “daisy chained” (in series) and led to a 600V rated disconnect like the Square D unit that Dave mentioned. 

Getting help from a local installer or engaging Dave (or both) is highly advised to ensure you have a safe system and don’t run into all of the gotchas after buying all of this pricey gear.  

offgridcabin2015

Thanks to you all for all chiming in. I Have my game plan now and all parts on order.

I think the disconnect/ or where i was getting confused is that i see a product that allows 4-16 strings and yet the charge controller is capped at 600volts. So to me i m thinking why make dis / comiber disconnect with so many strings. 

for ei i can only do 2 strings .   / 8 panels on first string i'm alredy maxed at my panels and can only parallel the next set of  8.
so i'm capped at 2 strings and the unit provides 2 more inputs.  Seems like a waste to me but mabe there are bigger charege controller out there. 

HOnestly i'm still learning and that's why i'm here. I"m ready to learn and understand more. 

i'm grateful for all who have chimed in. Thankyou.

littleharbor2

If you went with a 48 volt system instead of 24 volts you could double the amount of panels going into your controller. There's your 4 strings right there.