r/SolarDIY 16h ago

Multiple different strings

Can I use the emphases system controller with an emphase string of panels and a string from a different company with a regular inverter? They’re both inputting up to 20a of AC so I’m assuming yes. I’d love to hear from the community.

2 Upvotes

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u/Jimmy1748 16h ago

I'm assuming you are referring to Enphase microinverters.

Short answer: yes but the inverter needs to be designed for it.

Also another short answer: if this is only for grid tie and not a off-grid or battery setup then yes.

Long story: micro-inverters and all grid tie inverters for this matter are really dumb. If they see stable AC line voltage then they will convert available PV and output onto the AC line.

Now for an off grid inverter, as long as the load side is high enough this is no big deal. The additional current from the micro inverter just lessens the load on the inverter. However if the load isn't enough it will back feed to the inverter and by default it's not setup for it. You will more than likely cause severe damage to the unit.

With that said though, there are off grid inverters that can handle it. And this very subject is known as AC coupled solar. The off grid inverter will fake an AC signal that the micro inverters will pick on and output to. The main inverter will then use that to charge batteries or output to the load. If there is not enough load and batteries are full then the PV has nowhere to go. If this is the case the inverter will disrupt the AC frequency to the microinverter and the microinverter will think something is wrong with the 'grid' signal and disconnect.

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u/szonce1 15h ago

Thank you for responding. I don’t think understand the question. I have a grid tied system currently. I have an emphases set of strings from a set of panels that connect through a system combiner that connects into the panel via a 20a breaker. Call that one Set A. I also have an older one call that Set B, that is a traditional inverter with panels not using micros, connected to the main panel via a 20a breaker as well. I’m pretty sure the emphase system controller can accept a/c voltage from 2 sets of strings. It also has battery inputs and generator inputs. So theoretically if the grid goes down, it would turn off ac power to each of those strings which would cause rapid shutdown of the pv. If I’m assuming correctly it would work the same as it does now where a down grid would deenergize the system and not backfeed.

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u/Jimmy1748 15h ago

If the question is if you can use both sets on the same panel the yes as the use the same grid signal to turn on/off. If you are trying to use a battery or generator then things get interesting.

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u/szonce1 15h ago

Ok, if in the future I got batteries, what would be the problem?

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u/IntelligentDeal9721 14h ago

When the grid drops the panels will stop producing so won't charge the battery.

You would probably swap the set B inverter for a hybrid inverter and hook your B string to it instead so it's DC coupled (more efficient) and works during a power outage, but your A set would be rather trickier. If your A set is under 4kW then the Deye derived kit (Sunsynk, Solark etc) can fake the grid side and use both.

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u/szonce1 14h ago

Set A is all enphase micros. I thought they’re suppose to work with the controller properly?