Hey guys,

So I've spent the last couple weeks scouring the net as I'm looking to purchase and install an inverter system next month.

From all the research I have gone through it seems Sun synk and Hubble is the most common setup. 

I'm looking at buying an 8kw Sun Synk inverter and 1 x Hubble AM2 5.5kw battery.

I have some real basic questions just as confirmation of the research I have done: 

Q1 . I understand I would need 2 batteries to safely cover the maximum draw of the inverter. 8kw maximum draw is 185a and 2 x Hubble batteries would be 200a. Is this correct? I can only afford 1 x battery at the moment and will purchase the second battery as funds allow. Is there any advice or concerns using 1 battery temporarily?

Q2. I understand I would need to install a 10a relay for earth to neutral bonding. The inverter load earth and neutral require bonding to ensure the neutral does not float. Regarding the configuration of the earth wire, can the Grid Earth still be used? So for example the inverter load neutral is fed into the relay's (NO) circuit and the inverter loads earth is fed into the other side. The earth wire is then looped onto Grid Earth. Is this okay to do? Or should the earths be kept separate ie. using an earth spike instead?

Q3. Regarding the MCB's for the inverter, I am looking to purchase and use 40a, 2pole C curve MCB for the Grid feed to the inverter and 40a 2pole C curve on the essential load DB. Is this correct?

Q4. The Sun Synk manual specifies a 50mm squared cable for the battery connection. Is this sufficient and if so what fuse size would be recommended? I see so much back and forth on information surrounding cable size and fuse size, I'm not sure what to follow? Also does the cable size need to change if the number of batteries change? Or is this determined by the inverter maximum capable load of 185a?

Q5. What if there is little space available in the DB to install the CT around the Grid supplied cable from the municipal meter but before the mains breaker? How do you guys install this?

I will be purchasing all components directly and planning the installation. I will however use a qualified electrician to install the units for warranty purposes. But I would like to ensure all necessary steps have been followed and the job has been done correctly and in accordance to the information I have learnt from this forum. 

I look forward to hearing from you.

6 hours ago, The_Jelly said:

Q1

Hi Jelly, the concern here is that you will discharge beyond the specs of the battery & that will cause the Battery BMS to protect that 1 battery & the system will trip. Hence when one specifies a system you try your best to match the system as 1:1 at the very least. The Voltronics MAX system for example has a Maximum discharge limit setting for the battery bank. This limit will not be exceeded. I cannot talk on behalf of Equipment that I do not install, maybe a more knowledgeable person with a Sunsynk or Hubble can comment but this is the basis of where the.concern comes from. 

6 hours ago, The_Jelly said:

Q2

Again for a Sunsynk seasoned installer. My humble Voltronics has this neutral to Protective Earth bond done automatically within the machine. The Sunsynk/ Deye needs this item added externally. 

6 hours ago, The_Jelly said:

Q3

On face value this seems correct however, make sure you cover not just the 8kW of inverting capacity but also the pass through current that the Sunsynk can provide. The Sunsynk can conduct more than the 8kW because of this passthrough current. Observe that value if you can find it. Remember the Breaker is there to protect the wires, not the appliance. The wiring size must also be able to accept your breaker size. I have a feeling that the passthrough is carried out through a seperate port & might need its own breaker. A seasoned owner or installer might clear this one up for us. 

 

6 hours ago, The_Jelly said:

Q4

200A is ok for 50mm DC wire. There is a great guide in the downloads section called wiring unlimited by Victron. Great place to sniff. You can use smaller cable between the 2 batteries but your main + & - must be at least 50mm wire. This is where the maximum of the discharge of the 8kW inverting capacity will be delivered through. So example, if your Hubble is 5kWh each to make up 10kWh in parallel. That is 100ah X 2. So that means between these 2 batteries 100ah is delivered from them each. So the cables between the 2 can be up to 25mm (worthy of 100A). But the inverter will draw 184a through this bank of 200ah & it will use these wires to do that. So they need to be thicker. 

 

6 hours ago, The_Jelly said:

Q5

The placing of the CT coil is very important with the Sunsynk, it's grid tied architecture makes it very sensitive to where that CT is positioned. An experienced installer will guide you on this one. The CT is also quite small, it will fit into most places & again an experienced operator will get this right. 

Edited September 25, 20223 yr by Steve87

Hi @Steve87

Thank you for taking the time out to go through all my questions it is greatly appreciated!

regarding your reply's see below feedback:

Q1 response - I have seen via videos and documentation there is a section in the settings where maximum charge and discharge may be set. I however do not want to take this as gospel and do harm to the single battery. Agreed on waiting for feedback regarding this from a Sun Sync Fundi.

Q2 response - I am also not sure why this bonding does not happen internally its a good question. I understand the need for it and how it works and will wait on feedback regarding the sharing of the grid earth.     

Q3 response - Thank you for pointing this out. I did some digging and found a video by Sun Synk where Keith explains that the maximum passthrough is 12kw. Using this figure 12000w/220v is ~55amps. So I assume I would then use a 50a 2 pole MCB C curve together with a 8mm² cable.

Q4 response - Thank you for this it is super clear and makes complete sense. Also thank you for the pro tip on the on the Victron download section!

Q5 response - Awesome I will await further feedback regarding the CT coil 

I have made diagram in order for you guys to correct me. Am I on the right track regarding wiring configuration and protection? Does the inverter Grid feed require it to go through an RCD/Earth Leakage? And is there anything I should change to simplify or make the installation better/safer?

As mentioned above so far 50mm² cable will be used for the battery connection to the inverter. 8mm² cable will be used from the mains DB as Grid feed to the Inverter on a 50A 2 pole MCB. I suppose the same 8mm² cable could be used from the Inverter load output to the essentials DB using a 40A 2 pole MCB.

Let me know your thoughts.

Edited September 25, 20223 yr by The_Jelly
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I have been running through videos and screen shots about the battery settings and can see that they are fully adjustable. Could someone please confirm that If I only purchase 1 x Hubble battery on the 8kw and I correctly set the charge and discharge setting on the inverter that this is safe to do so regarding battery health?

Is it okay to purchase 1 battery now and put cycles on it, and add a new unused battery later? Does this cause any issues? Or would it just be a case of bite the bullet, buy the second battery to ensure the inverter cannot discharge past what the batteries are capable of and to ensure both batteries age together? Any advice is welcome!

I'm looking to secure a purchase as soon as possible. 

56 minutes ago, The_Jelly said:

I have been running through videos and screen shots about the battery settings and can see that they are fully adjustable. Could someone please confirm that If I only purchase 1 x Hubble battery on the 8kw and I correctly set the charge and discharge setting on the inverter that this is safe to do so regarding battery health?

Is it okay to purchase 1 battery now and put cycles on it, and add a new unused battery later? Does this cause any issues? Or would it just be a case of bite the bullet, buy the second battery to ensure the inverter cannot discharge past what the batteries are capable of and to ensure both batteries age together? Any advice is welcome!

I'm looking to secure a purchase as soon as possible. 

With Lithium you can buy one now then add another later without affecting the system balance - this is a key benefit over the other battery types. And the answer to your question is yes it shouldn't be an issue 

9 minutes ago, mzezman said:

With Lithium you can buy one now then add another later without affecting the system balance - this is a key benefit over the other battery types. And the answer to your question is yes it shouldn't be an issue 

Awesome that is exactly the info I was after. I'm hoping to buy the 8kw and the battery and cover a 2 hour load shed sufficiently. Save up and buy another battery to cover a 4 hour load shed or short power interruption. This second battery will then mean I can fully utilise the 8kw inverter should there be need for it. Then toward the end of next year purchase the solar panels to make use of the hybrid functionality.

Do you have any experience regarding Sun Synk inverters? Steve was an incredible help however some questions I still want to find out are specific to Sun Synk inverters.

 

Talk to @Leshen

Thanks for the heads up. I have seen @Leshen name pop on several posts I'll be sure to pop him a DM. Thanks man!

On 2022/09/25 at 10:40 AM, The_Jelly said:

I have made diagram in order for you guys to correct me. Am I on the right track regarding wiring configuration and protection? Does the inverter Grid feed require it to go through an RCD/Earth Leakage? And is there anything I should change to simplify or make the installation better/safer?

As mentioned above so far 50mm² cable will be used for the battery connection to the inverter. 8mm² cable will be used from the mains DB as Grid feed to the Inverter on a 50A 2 pole MCB. I suppose the same 8mm² cable could be used from the Inverter load output to the essentials DB using a 40A 2 pole MCB.

Let me know your thoughts.

Hi, thanks for this diagram. Is this neutral bonding needed at all? What happens if this is not done. I am also bbusy with a 8kw Sunsynk with one Hubble AM-2 for office backup oly. Planning to add panels and more batteries later. Thanks for your insight.

 

1 hour ago, Namreh said:

Hi, thanks for this diagram. Is this neutral bonding needed at all? What happens if this is not done. I am also bbusy with a 8kw Sunsynk with one Hubble AM-2 for office backup oly. Planning to add panels and more batteries later. Thanks for your insight.

 

Hey man, please don't use my diagram as gospel as I have a few questions regarding layout that I'm hoping someone on here can assist with. But it's a basic idea of what needs to happen. On the neutral bonding from my research it seems when the inverter moves to battery power there is nothing bonding earth and neutral. Earth and neutral are bonded by the grid as a default to ensure neutral does not get a floating voltage. From my understanding this is very much needed because if it is not there you can get voltage on your neutral which can damage appliances as well as make your neutral dangerous. This again is my basic knowledge through the research I have done. Some guys have reported measuring up to 100v on the neutral which is not good at all. My advice would be install the relay and don't take a chance. 

21 minutes ago, The_Jelly said:

Hey man, please don't use my diagram as gospel as I have a few questions regarding layout that I'm hoping someone on here can assist with. But it's a basic idea of what needs to happen. On the neutral bonding from my research it seems when the inverter moves to battery power there is nothing bonding earth and neutral. Earth and neutral are bonded by the grid as a default to ensure neutral does not get a floating voltage. From my understanding this is very much needed because if it is not there you can get voltage on your neutral which can damage appliances as well as make your neutral dangerous. This again is my basic knowledge through the research I have done. Some guys have reported measuring up to 100v on the neutral which is not good at all. My advice would be install the relay and don't take a chance. 

Perfect thank you, I agree.