Parallel systems

[Mrjmegson]

Hey guys,

My system is setup and running well, thanks to a firmware update.

The inverters are paralleled together, and all seems good.

I know John and a few other people were intrigued to know how the inverters dealt with being paralleled, but I don't understand the workings enough to give you any info without you asking directly for it, so fire away with specific questions and I'll try get the info for you.

What I can tell you is:

When the inverters weren't paralleled they fought each other, and seemed to me to think the opposite inverter was the grid. They also charged each others batteries from their own batteries, but I stopped that by turning off AC charging.

Now they are paralleled, only the master deals with loads, and the slave just does as it's told. So in the app, the master shows consumption, but the slave doesn't, which I quite like. The slave still shows its own solar production and battery charge/discharge figures.

Right, enough waffle, what would you like to know?

Jay

 

[bladerunnerpv]

Hi MrJ, glad to hear it's running, and for the follow-up

IIRC the inverter spec said something about being able to be paralleled but little else.
1 does no AC charging mean you can't top-up the batteries from the grid?
2 Whay type of settings did you change to get the master slave priorities?
3 does each inverter have a CT clamp? If so, where?
4 each inverter has a battery?
5 how are the inverters connected to the CU?

cheers, enjoy all those sunny kW!

 

[Mrjmegson]

1. There are settings for AC charging. You can turn it off totally like I've done, which stops any ac charging of batteries, or you can turn it on, which then requires min and Max soc to be set, or you can set timed AC charging.
2. The inverter has a menu called Parallel, and it simply asks you to set parallel on, then tell it how many inverters there are, then tell it what the particular inverter you're working on will be, master/slave, and it sets the address and gives a default baud rate, which I left (9600). They are networked together through a com port using RJ45 cable.
3. Yeh each inverter has its own CT, both of which are on the incoming positive tail, with an arrow facing the load.
4. Sort of. The rear roof inverter has 5 batteries, 25kwh, and the front roof inverter has 3 batteries, 15kw.
5. Each inverter has 10mm live and neutral lines, each connected to 32A MCB on a bus bar with the main switch, so not in with the RCD circuits.

Hope all these replies made sense.

 

[bladerunnerpv]

Thanks MrJ, well done for getting it working

1. Do you think the timed AC option would work or is it a no-go with each hybrid inverter having batteries.
Or did connecting the inverters and making them parallel enable battery charging from the grid again?

2. sounds easy enough

3. ah, for some reason I had wondered if it would only be the master with the CT

4. wow

5. so both inverter's AC out go into the one CU?

6. Does the master inverter control the backup power AC out and pull from all the batteries, any idea if it drains slave system's batteries first or pulls evenly from all? Presumably at 6kW, 240V that's 25A supply?

food for thought indeed ...

 

[Mrjmegson]

Cheers, I'm very pleased with it so far, and it just keeps better better as I tweek things.

1. The AC charging is fully functional, I just turned it off as I don't have a TOU tariff, so may as well just use grid power direct rather than incurring all the losses putting it in and taking it out of the batteries.

3. Despite being paralleled together, they still work individually, so both need to see what's going on.

5. Yeh, they both feed into the CU. As above, they work independently.

6. a. So these inverters (no idea about others), both work independently to give or take energy, so they both output to the CU, and they both charge and discharge their own batteries, it's just that the master inverter tells the slave what to do.
b. I've seen the system do all sorts of things with regard to pulling from the batteries, pull evenly from both, pull unevenly from both, pull from just one set, but I haven't worked out the corolation yet, it's definitely not charge dependant though, as last night it drained the smaller, slave batteries mainly, and just trickled in from the larger master pack.
c. The inverter can actually peak a lot higher than 6kw at times, but yeh in general it's 26A.

On a side note, today has produced 11kw so far, and charged the big battery pack upto 43% and the small pack to 40% at the time of writing. The small pack started the day totally drained at 15%, and the larger pack was on 19%, so some healthy charging.