Hello all,

I am a novice when it comes to Solar but I need some advice on expanding battery storage capability. Installed a 5000W PV array less than a year ago over a 8KW Victron inverter and 7Kwh pylontech batteries (2 x 3.5kwh). Now ready to increase battery storage to 21Kwh from 7 Kwh and also add additional PV arrays to take advantage of the 8KW viltron inverter. Meaning I will be adding an additional 4 x 3.5kwh to the battery bank.

My questions are:

1). How many  3.5KWh pylontech batteries can I connect together in parallel without making the interconnecting cables too hot and starting a fire? I have heard of cases where people connected 6 ZTE batteries (3.5KwH) together and cables were getting hot and melting. I don't know if this will be the case with the pylontech brand. I will definitely employ the services of a professional to do the job but just like to have an idea of what is to be done before embarking on the project. 

2). Can I go above 8KW on my PV Array since my inverter is 8KW without having any issue? Plan is to add additional 3600W or 5600W depending on available space.   

3). What other advices or tips can you give me based on my system configuration above.

Thank you all in advance. 

Much Appreciated. 

Danny

Danny,I cannot  give you an answer on all the questions but I'll give it a try:

1). Read @Youda's lab from here. He moved to pylons as well and later on he expanded. Very nice to read!

2). Does your Victron have MPPT inside? What type is it?

How much power are you drawing from your system?

Rik

 

On 2020/06/30 at 4:46 PM, Danny said:

2). Can I go above 8KW on my PV Array since my inverter is 8KW without having any issue? Plan is to add additional 3600W or 5600W depending on available 

Hi Danny

Do you have the 8kVA Quatrro?

For Victron, you will have an MPPT charge controller that you connect your solar to. I’m pretty sure you can add as many as you like.

The 8kVA is just the maximum amount you can invert. So basically, take from DC to AC (or AC to DC). But on the DC side, you should be able to happily charge as much as you want.

As an example, assume you have the momentary potential to generate 10kW with your PV. Your house’ demand at that moment 6kW and your batteries are 50% full. Then of the 10kW, 6kW will be inverted and used in the house and the remainder would charge your batteries.

If your batteries are already full, you would only invert the 6 and the other 4 would be “wasted”.

Regarding adding additional batteries: My advice (for what it is worth) would be definitely to add more, like you intend. The 2xUS3000 is technically under spec for just a 5kVA inverter. For your 8kVA inverter, they will struggle to meet even just half the demand when you are getting close to your 8kVA inverting capacity.