Combiner Box for (2) 30 amp arrays?

[jmoles]

I have a roof plan with Hoymiles microinverters and I was planning to have two arrays on separate wiring. Each would need a 30 amp breaker.

I'm having a little trouble figuring out the combiner box. For permitting, do I need to have a UL listed box specifically for PV systems?

When I'm looking around online for a combiner box the prices seem all over the place. From $50 up to $700. I'm trying to understand what products I actually need.

Attached is the electrical diagrams I've drawn up with how I'm currently trying to lay it all out.

 

[Hedges]

Usually we say "combiner box" to mean PV strings connected in parallel.
"PV aggregator panel" for AC connections.
The words mean the same thing, just seems to be customary.

When PV inverters backfeed a breaker panel, 120% rule says sum of PV breakers and main breaker or other OCP feeding the panel can't exceed 120% of busbar rating.

Except, if we call it a "PV aggregator panel" and swear we will never connect any loads, then sum of PV breakers can be up to 100% of busbar rating.

You could use a 60A or 70A breaker panel for PV aggregator.

You could use a 125A breaker panel, protected by up to 125A x 120% - 2 x 30A = 90A OCP. And connect other loads.

In either case, a 60A fused visible blade disconnect could be used with a main lug panel (no main breaker.)

I have a 100A fused disconnect, and mounted DIN rail and 2x 2-pole 60A breakers to feed my inverters. That arrangement might raise some eyebrows. Normally, there would be a bezel preventing access to exposed terminals. The switch cover is interlocked, so must be turned off before cover is opened. You're better off with a separate breaker panel so it doesn't look goofy.

I find myself expanding in the future, so good to have extra capacity.

 

[ncsolarelectric]

I have a roof plan with Hoymiles microinverters and I was planning to have two arrays on separate wiring. Each would need a 30 amp breaker.

I'm having a little trouble figuring out the combiner box. For permitting, do I need to have a UL listed box specifically for PV systems?

When I'm looking around online for a combiner box the prices seem all over the place. From $50 up to $700. I'm trying to understand what products I actually need.

Attached is the electrical diagrams I've drawn up with how I'm currently trying to lay it all out.

https://www.lowes.com/pd/Siemens-125-Amp-8-Spaces-16-Circuit-Main-Lug-Load-Center/3129435

Most customers use one of these outdoor load centers.

 

[zanydroid]

125A with 60A main breaker at this subpanel and 60A at the subpanel feeding it is the easiest to get past code check.

If you plan to expand you may want to pull a bigger feeder; you can land the bigger wires in the same size breakers. For instance you can use Al SER 2-2-2 to get to 90A (IIRC) for small incremental cost & labor

 

[AdvicetotheGraduate]

https://www.lowes.com/pd/Siemens-125-Amp-8-Spaces-16-Circuit-Main-Lug-Load-Center/3129435

Most customers use one of these outdoor load centers.

I see that Hoymiles has a combiner box here: https://www.hoymiles.com/product/microinverter/accessories/combiner-box/

But I can't find anywhere that sells it.

Are you saying that for a Hoymiles system there is no special combiner box needed? I believe for Enphase they require you to use their special combiner box that has a gateway / Envoy.

Thanks

 

[zanydroid]

I see that Hoymiles has a combiner box here: https://www.hoymiles.com/product/microinverter/accessories/combiner-box/

But I can't find anywhere that sells it.

Are you saying that for a Hoymiles system there is no special combiner box needed? I believe for Enphase they require you to use their special combiner box that has a gateway / Envoy.

Thanks

I didn’t use one.

I can’t click the links within that Hoymiles webpage.

Anyway even the DTU (the bridge between internet and proprietary protocol — 2.4ghz and 900mhz) is optional on Hoymiles. As is the CT energy monitor.

Hoymiles takes a much more a la carte approach than Enphase. Enphase wants you to buy the box that has all this stuff in it. There are pros and cons

 

[ncsolarelectric]

I see that Hoymiles has a combiner box here: https://www.hoymiles.com/product/microinverter/accessories/combiner-box/

But I can't find anywhere that sells it.

Are you saying that for a Hoymiles system there is no special combiner box needed? I believe for Enphase they require you to use their special combiner box that has a gateway / Envoy.

Thanks

That is correct. You can use any OTS AC sub-panel to combine branch circuits going into the disconnect. Like this...

 

[solar-mike]

I see that Hoymiles has a combiner box here: https://www.hoymiles.com/product/microinverter/accessories/combiner-box/

But I can't find anywhere that sells it.

Are you saying that for a Hoymiles system there is no special combiner box needed? I believe for Enphase they require you to use their special combiner box that has a gateway / Envoy.

Thanks

For the Enphase systems, you can use their Combiner Box OR use a standard load center with the IQ Gateway/Envoy connected to it.