Solar PV advice

[Stinsy]

Thanks Stinsy...

Will leave it to the spark to have a look when they get round to installing in a couple of weeks.

But I was correct in thinking that ideally there should have been 2 positive and 2 negative connectors on to connect the batteries in parallel?

I don't think "should" is the correct term. Some do. But they tend to be much smaller eg pylontech 4.8kWh packs. Your ones are much bigger so maybe they need to be individually terminated to a bus bar or similar for the sake of the cables/connectors...

[Richard77]

Sorry for the quick sketch and dodgy writing!



Is that possible if there is enough room in the inverter for two of each cables?

[Richard77]

Thanks Stinsy...

Will leave it to the spark to have a look when they get round to installing in a couple of weeks.

But I was correct in thinking that ideally there should have been 2 positive and 2 negative connectors on to connect the batteries in parallel?

I don't think "should" is the correct term. Some do. But they tend to be much smaller eg pylontech 4.8kWh packs. Your ones are much bigger so maybe they need to be individually terminated to a bus bar or similar for the sake of the cables/connectors...

It's just that I noticed on the similar specced fogstar models they had two of each.

[Richard77]

Thanks for the info guys...

I've got my head around the power distribution posts/busbar box now.

I think that's what will be needed as I can't imagine there being room to be able to squeeze 2x 35mm² cables into the SunSynk 8kw inverter for each of the positive and negative. From pics/videos looks like it's a tight fit to push one up there nevermind 2!

[Marcus]

Iirc you're using a 12kw inverter?

That's 250A going on 300A when the battery is low. Personally, I'd avoid daisy chaining batteries at that current anyway. I'd run both batteries direct to the inverter if at all possible, especially if the cables are only 35mm2. If you have to combine on an external post, I'd consider getting 70mm2 for the link to the inverter.

[Richard77]

Iirc you're using a 12kw inverter?

That's 250A going on 300A when the battery is low. Personally, I'd avoid daisy chaining batteries at that current anyway. I'd run both batteries direct to the inverter if at all possible, especially if the cables are only 35mm2. If you have to combine on an external post, I'd consider getting 70mm2 for the link to the inverter.

Hi Marcus...

Thanks for the suggestions.

It's only the 8kw SunSynk. Couldnt get dno to approve the 12kw. They approved the 8kw with an export limit of 6kw.

[Richard77]

If I go the post route and use 70mm² to the inverter, I suppose the 2x 35mm² would have originally fitted. So wouldn't need to go down the post route in the first place.

I really could do with finding out what size cable physically the 8kw SunSynk can take thickness wise. (seems it's 70mm²)

Update edit: maybe 2x 35mm² will fit.



What's everyone's thoughts on DC isolator between battery and inverter? I'm sure I read somewhere they are not recommended any longer.

[MrPablo]

A fused isolator such as NH1 fuses in a Frankenstein style enclosure should be used between battery and inverter.
I mention NH1 as the more usual NH00 might not go up to the current rating you'll need.

Alternatively you could just have a fuse and a separate isolator, but the combo units are pretty compact.
Ideally you'd want a fuse per battery pack, I'm not sure if there's anything built into the enclosures you have.

The dc isolators that tend to not be recommended are for solar, I think it's because breaking a high voltage DC arc is not always straightforward. As a result, there's more risk of things going wrong.

[Richard77]

A fused isolator such as NH1 fuses in a Frankenstein style enclosure should be used between battery and inverter.
I mention NH1 as the more usual NH00 might not go up to the current rating you'll need.

Alternatively you could just have a fuse and a separate isolator, but the combo units are pretty compact.
Ideally you'd want a fuse per battery pack, I'm not sure if there's anything built into the enclosures you have.

The dc isolators that tend to not be recommended are for solar, I think it's because breaking a high voltage DC arc is not always straightforward. As a result, there's more risk of things going wrong.

Thanks MrPablo

[Colin Deng]

Parallel connection should be like this
Sorry for not answer in time

Got a busy weekend