There are many types of inverters - even the definition Hybrid is not consistent anymore.
Anyway - I'm trying to define a simple definition for a complex config.

Would it be true that an inverter is either AC-oriented or DC-oriented when functioning in standard mode of operation?

Any grid-tie inverter would be AC-oriented ; it can however still work on DC, but the "standard" operational functioning would be around AC.
My setup (Axpert type of inverters , Kodak OG Plus 5.48) function primary from solar and batteries would will make it a DC - oriented inverter.

This thread is not to discuss which one better, just to validate if above statement would be true? 
 

1 hour ago, Marius2001 said:

There are many types of inverters - even the definition Hybrid is not consistent anymore.
Anyway - I'm trying to define a simple definition for a complex config.

Would it be true that an inverter is either AC-oriented or DC-oriented when functioning in standard mode of operation?

Any grid-tie inverter would be AC-oriented ; it can however still work on DC, but the "standard" operational functioning would be around AC.
My setup (Axpert type of inverters , Kodak OG Plus 5.48) function primary from solar and batteries would will make it a DC - oriented inverter.

This thread is not to discuss which one better, just to validate if above statement would be true? 
 

My 2c. I just don't think your statement is universally true. What do you mean by "standard mode of operation" I'd suggest to use the terminology "ac-coupling" and "dc-coupling" of battery storage to draw clearer lines.

In your case with your off-grid inverters, they are DC-coupled, ie. the solar panels convert energy and transfer to the battery, all using DC. And then in parallel to the battery, the DC/AC inverter can supply 230V AC onward to your loads. These are not grid-tied inverters in the sense of being embedded into the national grid for export of power back to Eskom.

On the opposite end would be pure grid-tie inverters like micro-inverters, that convert DC from the solar panels straight to 230V AC, but they do not have any further DC output for battery power storage, they just send to grid. It's possible to add a second (battery) inverter for storage at the same location to form a micro-grid, and in that case, it would convert the AC-output of the micro-inverter back into DC for the battery. That would be AC-coupling of battery storage.

In the middle would be the typical grid-tied hybrid inverters like Sunsynk/Deye, however it's difficult to speak of "standard" operational functioning being around AC. Yes, the output of the inverter is AC, and it is embedded into the grid for export through the bi-directional load port just like a grid-tied inverter. On the DC-side it also receives solar DC inputs to the MPPT's, for DC-coupled storage to the batteries, just like your DC-coupled Axpert-type. However it is also capable of AC-coupling to a micro-inverter on the AUX port. AC-coupling might just not be considered the "standard operation" but the capability is still a given.

I hope this makes sense to frame it like this. Open to other views.

 

Edited January 10, 20251 yr by GreenFields

IMHO, the inverters cannot be divided into clear and hard categories, as there are many possible modes, scenarios and features they utilize. And they can switch modes of operation too.

For example, the Axpert King is a typical off-grid inverter, but it's capability of double conversion makes it more like online UPS. Some people would even say that it's a hybrid, as it can blend the energy from PV, batteries and grid together. On the other hand, contrary to classic hybrids, Axpert King is not able to export excess energy back to the grid.

Similarly, Victron Multi is being perceived as off-grid, DC coupling inverter, but technically it's a full hybrid, as it can export excess to the grid and blend PV + grid together. And it can do both - DC coupling and AC coupling too.

And last, some Axpert VM models are capable of mixing PV + Grid together, or even run without batteries, just with PV+Grid. And while they are not designed for export to grid, they can produce "spillover" and export small amounts of energy. So, it's technically a hybrid, although with a very bad management possibilities and definitely not a viable choice when you want to export surplus energy and got paid for it.

Still, there are some main characteristics, and their combinations, that you can identify within an inverter in order to imagine where it will fit and where not:

String Inverters

• Description: These are centralized inverters connected to a "string" of solar panels.
• Features:
  • All panels in a string feed their power into one inverter.
  • If one panel is shaded or underperforming, it can affect the performance of the entire string.
• Best Suited For:
  • Installations with uniform sunlight exposure.
  • Simple, flat rooftop systems.

---

Microinverters

• Description: These are small inverters installed on each (or each two) solar panel (s).
• Features:
  • Each panel operates independently, so shading or failure on one panel doesn’t affect others.
  • Higher energy harvest in partially shaded or uneven installations.
• Best Suited For:
  • Complex rooftops with shading issues.
  • Systems requiring maximum energy production efficiency.

---

Power Optimizers

• Description: Not inverters by themselves, but work with string inverters to optimize the performance of each panel.
• Features:
  • Installed on each panel to manage power output individually.
  • Combined with a central inverter for energy conversion.
• Best Suited For:
  • Installations needing panel-level optimization but with a centralized inverter.

---

Hybrid Inverters

• Description: These are capable of managing power from both solar panels and battery storage.
• Features:
  • Allows solar energy to be used, stored, or fed into the grid.
  • Provides backup power during outages (if combined with batteries).
• Best Suited For:
  • Systems with battery storage or plans to add batteries in the future.

---

Off-Grid Inverters

• Description: Designed for standalone solar systems not connected to the utility grid.
• Features:
  • Works with batteries to provide energy during nighttime or cloudy days.
  • Does not interact with the grid, but may switch to grid once the batteries are depleted.
• Best Suited For:
  • Remote locations without grid access.
  • Off-grid systems.

---

Grid-Tied Inverters

• Description: Designed to synchronize with the utility grid.
• Features:
  • Feed excess PV energy into the grid.
  • Require the grid to operate (do not work during power outages without battery support).
  • Do not support batteries.
• Best Suited For:
  • Urban or suburban homes connected to the utility grid.
  • Net metering setups.

---

Battery-Only Inverters

• Description: Standalone inverters designed exclusively for managing battery systems.
• Key Features:
  • Convert stored DC power from batteries into AC power for use in appliances or the grid.
  • Often used to retrofit batteries into existing solar systems with separate inverters.
• Best Suited For:
  • Retrofitting battery storage to an existing solar system.
  • Dedicated battery backup systems.

 

Regs,
ChatGPT

2 hours ago, Marius2001 said:

I'm trying to define a simple definition for a complex config.

IMHO, the possible approach in order to define a system is:

• Distinguish between systems that are built around a battery and the battery-less systems.
• Distinguish between systems that are meant for exporting back to the grid and the systems that are meant just for self-consumption, even if they can import from the grid or genset.
• Use AC coupling / DC coupling categories as @GreenFields mentioned.
• Explain future scalability scenarios and limitations.

That would give you major characteristics that you can discuss with you client, for example, in order to explain how the system will work for him.

 

BTW:

It's not about the components or inverter(s), but about a whole setup. For example, a set of Victron Multis used in the offgrid mode would fall into a "self-consumption" category. Their capability of reconfiguration for exporting excess PV to the grid would be the "future scalability" then.

Edited January 10, 20251 yr by Youda