Dumb question - can you usually run inverters in parallel?

[Alan Ambrose]

I'm particularly looking at the Sigenergy SigenStor Energy Controller 6.0 SP 6.0kW 1-Phase...

 

But a general question - if you're planning more panels than the inverter will handle for max DC voltage reasons - can you simply parallel them? I imagine the software has to be smart enough to do that.

 

For instance, with strings of 11 panels each giving, say, 380 VDC max / 5.4 kWp and an inverter which will accept 550 VDC max, would I be able to run several strings with several inverters 'in parallel'?

[Nickfromwales]

51 minutes ago, Alan Ambrose said:

I'm particularly looking at the Sigenergy SigenStor Energy Controller 6.0 SP 6.0kW 1-Phase...

 

But a general question - if you're planning more panels than the inverter will handle for max DC voltage reasons - can you simply parallel them? I imagine the software has to be smart enough to do that.

 

For instance, with strings of 11 panels each giving, say, 380 VDC max / 5.4 kWp and an inverter which will accept 550 VDC max, would I be able to run several strings with several inverters 'in parallel'?

Yes. It’s quite common practice amongst the Chinese stuff.

 

Typically you’ll have a master unit that provides the 50hz metronome to the slave units, linked by the AC signal or a cat 5 cable. 
 

Been a good while since I dipped my toes into this stuff, so I expect a lot of the more reputable industry standard manufacturers are also ‘parallel capable’ by now. 

[Dillsue]

41 minutes ago, Alan Ambrose said:

I'm particularly looking at the Sigenergy SigenStor Energy Controller 6.0 SP 6.0kW 1-Phase...

 

But a general question - if you're planning more panels than the inverter will handle for max DC voltage reasons - can you simply parallel them? I imagine the software has to be smart enough to do that.

 

For instance, with strings of 11 panels each giving, say, 380 VDC max / 5.4 kWp and an inverter which will accept 550 VDC max, would I be able to run several strings with several inverters 'in parallel'?

If you're paralleling the inverters and they are grid tied to the house AC, then you can connect multiple inverters, subject to the usual DNO restrictions. Unless there's some quirk of the inverter, they just autonomously pump power into your house/grid. We've got 2 PV inverters and soon to have a battery inverter all running in parallel with no control between them.

 

Just watch out for voltage rise in the house if you're producing alot of power. The DNOs obligation is to limit the voltage at your service fuse to 253v. If you're trying to push alot of power into the grid through undersized cabling within the house, then you might find the house voltage rising significantly!!!

[Nickfromwales]

7 minutes ago, Dillsue said:

If you're paralleling the inverters and they are grid tied to the house AC, then you can connect multiple inverters, subject to the usual DNO restrictions. Unless there's some quirk of the inverter, they just autonomously pump power into your house/grid. We've got 2 PV inverters and soon to have a battery inverter all running in parallel with no control between them.

 

Just watch out for voltage rise in the house if you're producing alot of power. The DNOs obligation is to limit the voltage at your service fuse to 253v. If you're trying to push alot of power into the grid through undersized cabling within the house, then you might find the house voltage rising significantly!!!

The units I referred to would do UPS / EPS in a black or brown out, where the 50hz metronome from the grid goes bye-bye. AC coupled parallel inverters would instantly go into island mode and shut down.

 

Hybrid units would allow the 50hz signal to be created artificially, and then the solar and batteries would perform as normal in a power outage. You can even then connect a genny to charge the batteries simultaneously if you want to use a lot of power / sunshine isn’t suffice. 
 

Lots of different products / options / scenarios / solutions. 
 

Best to choose inverters that offer export limitation too, as at >253v your inverter is supposed to switch off. 

[JohnMo]

I'm running 3 inverters. 1kW, 3kW and 3.6kW. I take 3.6kW and 1.0kW in to a small consumer unit with C Curve Type A Double Pole Compact RCBO (Bi-Directional) as they feed down the same cable to the house. None of the inverter talk to each other - its crude but no issues.

 

Over clocking the inverter is easy enough. The 3.6kW has 5.8kW of panels connected to it (within voltage limits). I just accept that at around midday a whole chunk of electric could be clipped off. I have over clocked for winter performance, not summer in summer I generate a tonne anyway.

 

The 3kW has export control and can switch the whole array off if the battery is full and I am at my export limits. 

 

Our voltage today has been about 245V at some points I was generating 6.5kW.

Edited 3 hours ago by JohnMo

[JohnMo]

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Edited 3 hours ago by JohnMo

[Alan Ambrose]

OK lovely, thanks for all the feedback - looks like that scheme will work fine then.

 

Like @JohnMo, I'm thinking of shoulder months / winter performance and also as @Nickfromwales mentioned UPS-style backup. In the Sigenergy line-up this seems to require the 'Gateway HomeMax' and apparently will take a connection to a max of 3 inverters. It looks like I need to do some wading through manuals.

 

FYI I discovered these DC contactors & arc protectors recently:

 

Fire Safety Devices

 

ArcBox - Solar Connector Enclosure