Hi guys, looking for some help.

I am busy installing 4 x Luxpower SNA5000, 36 Canadian 600 Watt panels and waiting on 34 280aH Lipo4 cells coming from China. I have an electronics background, so planning to do the install myself, then have a pro come in and do a CoC.

My question is this - I need to pull cable cable through the existing conduit from my main boundary supply db to my "solar room". There are 2 conduits running there from the boundary box but I have found it impossible to pull through anything bigger than 4mm wire. 4mm is doable, but I really need much bigger like at least 16mm. So I am thinking of pulling in 6 x 4mm pairs, 3 pairs input and 3 pairs output. So I would be paralleling 3 x 4mm wires to get me in the ballpark. In theory a 4mm cable can carry 32 amps. I understand the circuit breaker is there to protect the cable, so I am thinking of running each set of 3 wires on a 3 pole 32 amp circuit breaker at both ends and on both live and neutral. These would then be bridged together on the other side of the breakers. What do any qualified / experienced folks think of this plan? Wires will be 42 meters long. Hopefully I have explained it reasonably well 🙂

My solar room is positioned in a way that makes it super difficult / expensive to do a new cable run to it.

Your time will be much appreciated!

 

 

Hi Kasman,

Sounds like a great project. What you are trying to achieve by running your wiring through an existing main boundary supply is the neatest option but if you can't get your initial cable thickness in I would say abandon the idea. The main reasons are because if you struggle to make the initial cable with a single wrapped and insulated cable I can tell.you that trying to fish tape your way with numerous cables into a tight duct is extremely difficult. The more you push through the tighter the space becomes. Cooking oil works well to assist but I think if a new conduit is done neatly will save a lot of frustration and will not disturb or damage the incoming cable. Yes you may have to create a new duct and this can be messy but will make for a neat outcome once plastered again and placed in the suitable insulation under ground. 

I would definitely opt for the alternative wiring option and I would use 12mm cable as this is more than sufficient for your power requirement. 

Give me a shout if you require a CoC inspection if you are in the Gauteng area. 

Also interesting project on the Batteries. Which BMS will you make use of for the project?

@steve87

 

Thank you for the help. I for sure will need you to come and do the CoC for me. Heard great things about you on this forum. Perhaps you can quote me on a pre-install site visit to get me on the right path?

Would the way I want to do it be legal at least? It actually works out cheaper as well as more convenient. My understanding is that 3 x 4mm cables will handle more power than a 12mm cable? The problem is not the space for the wire, its the stiffness through all the bends. If I am honest, it has a lot to do with the cost of the wire! I am stretching the budget on this system to the absolute max.

On the batteries, I am trying something a little different. Instead of the usual 16s configuration I want to try 17s to increase the voltage a little as this will reduce the current I use. I will have 2 banks like this with 2 x BMS. I will then charge each cell with a max of 3.5 volts or a little less. This should be much easier on the cells and extend my cycles.

I have got 2 x JK BMS which can do up to 24 cells and has a 2 amp active balancer onboard. So it pulls 2 amps from the highest cell and pushes it to the lowest cell. Very nice bms. Andy from off-grid-garage on youtube has some nice videos about it.

Edited June 19, 20224 yr by KASman

For the reasons mentioned, you can do this. At the end of the day 12mm wire and 4mm X 3 will have the same amp rating. If however, you make use of a Fish tape which usually come in 50m and 100m lengths this should be able to pull your wire through if as you say it's not as tight a fit as I thought. Yes 12mm wire or even 16mm wire is expensive & yes that length will be in the region of R7k or more😨

I know from a wiring perspective I'd much rather work with a single wire more than multiple wires. However, you can also make use of 3 phase or 4 core wire which has 4 wires enclosed + an Earth wire. 

Many more questions to ask, however, to understand the application of your installation. Is this for a 3 phase supply or for a Single phase ?

On the battery side, you are in the right direction. Your thoughts on 17s is very conservative. Pylontech do the 15s arrangement. My thoughts are even more conservative, I like to keep cells at no higher that 3.45V. So I float and bulk at no higher than 54.5V and once a month do a top balance to 55V. I have zero experience with the JK but I have seen Andy gives it a lot of respect. I am more of JBD fan & I love the idea of a physical contactor more than a MOSFET. Pylontech build the same arrangement via a Contactor.  But its horses for courses. Both BMSs are good. I use an external active balancer & this works well for my battery builds. Again horses for courses. 

I would love to visit your site & assist, even if just for the sheer experience & joy of watching another successful battery build get off the ground & reach a successful outcome. 

I have built around 5 sets of battery builds as you describe above so I can definitely assist. I have built with smaller 120ah cells to the larger 280ah. Also if you are tuned into Andy's channel you already have a great mentor. The AC side looks to be your challenge & I will gladly point you in the correct direction.

I will PM you my details. 

 

Hi  Steve

I have 3 phase but will be using only 1 phase after this install. Reason is I want to connect my 4 inverters in parallel so that I never overload any one of them. I do a lot of high electrical demand stuff at home like welding etc etc. This way I have 20kW available should it be needed. I don't want to have to worry about running the welder and wondering if someone else is boiling the kettle and operating the oven, or whatever combo.

Super happy that my method will work as it works out a lot cheaper, so I should be able to safely run 32amp x 3 = 96 amp, but each wire is 100% protected, so if one wire disconnects itself, the whole circuit will be limited to whatever is available. Even neutral will also be covered the same way.

On the DC side I feel very comfortable, that is my area! I know I can make the whole system "work perfect", but what I need is to make sure I am compliant, as I want to make sure insurance still covers me. I also want to talk to my insurance company about covering the system, especially with regards to lightening because I feel in JHB lightening could very easily toast the whole system, which would be very unfunny.

Thanks for your details. 

 

6 hours ago, KASman said:

I also want to talk to my insurance company about covering the system, especially with regards to lightening because I feel in JHB lightening could very easily toast the whole system, which would be very unfunny.

 

Yep, JNB is a high risk zone. If proper Earth bonding of the physical structure of the Solar PV array is done as per the guide of the SANS-10142, and Surge protection is installed on the DC and AC side, you may loose a few panels with a direct lightning event, but everything downstream will be saved and not affected. There is no way to prevent the loss of a few panels with a direct hit. The lightning has an entry and exit point. Both these areas will be badly damaged. The rest all good. 

Wouldn't panel flex cable work easier than normal gp wire? The price difference isn't that much but it work 100 times easier.

Another aspect to consider is voltage drop over distance. It can't be more than 5% Voltage drop over the distance. 

@VaalI don't think you are allowed to use fine cored wire for cable runs. I think its because it is too easy to break some of the wires which would derate the wire. I don't know fore sure though.

 

@Steve87Thank you. I may have to try 6mm cable according to those numbers or limit to lower value circuit breaker, perhaps 3 x 25 amp.

10 hours ago, KASman said:

@VaalI don't think you are allowed to use fine cored wire for cable runs. I think its because it is too easy to break some of the wires which would derate the wire. I don't know fore sure though.

 

As you indicate you are not sure of fine strands for cable runs. This is the 1st time I hear about this and don't think this is a problem. They must just be used with a thin ferrule when a screw does the clamping without a saddle.

It would be great to get confirmation on this.

I would think that it doesn't matter. The important thing is that the insulation is rated high enough for the specific voltage. Normal house wire is rated at 1000V.

Edited June 23, 20224 yr by Jacques Ester

I was struggling my behind off with normal GP wire between db and inverter and inside the db. Then a very good friend (he is a master electrician) asked me why I don't use the panel flex wire. I then replaced all the gp wire and wired my db with it also. He does coc's and the ac integration of pv systems, so he knows his story. 

@Vaal Thank you! I might then go ahead with using the same wires as I am using on my panels in that case. It is 6mm and very nice to work with compared to general house wire. Insulation looks far superior to house wire.... I can then wire in 3x6mm as described.

Quote

"36 Canadian 600 Watt"

 

Is the 600W panel not 13A panels and the SNA is only a 11  amp unit? witch means you will be over on the recommended mmpt amps. Also assumin you are strining the panels not to go over 400V MANUAL RECCOMEND i THINK IT WAS 385V. THEM 600w OPEN VOLTAGE IS PRETTY HIGH. 

 

I posted a link if issues I am having with my one SNA - one being the "REMOTE MONOTIRING" that is actually not working its a local connect via WIFI, the remote monitoring only works if you have a installer code. So i am also not sure if you will see the fancy monitoring that you see in youtube videos, specially if you running them in parallel. 

 

Its currently my issues just take note. 

@PeterGThe 600 watt panels are just over 17 amp. You can bridge the 2 x MPPT to each other to run that amperage. I will be putting 9 panels in series on each inverter. I have an inverter on that I am testing. I can see all the remote monitoring no problem at all. I do have an installer account though.

I wanted full control of my inverters, else I would have gone another route. I need to be able to change my setup as I see fit as I am going to run a non standard battery configuration.

I can put you in touch with the local support team if you are not. They are very helpful and friendly. They can create an account for you no problem at all. You then just add the dongle number and Bobs your uncle.

Cool beans. You sorted then. 

 

It would be appreciated if you can put me in contact. We testing a system at work or trying to to run offices independently and that why i wanted and liked the luxpower interface. 

On 2021/01/21 at 9:46 AM, YellowTapemeasure said:

The nswer to your question (highlighted in the quote) is yes, it does feed excess solar to power non-essential loads.