ᐅ Inverter: What Should You Consider?

Hello everyone,

Yesterday, quite by chance, I watched a YouTube video where someone reviewed their past year with a photovoltaic system and its battery storage. Since I don’t know much about this, and the guy was using exactly the hybrid inverter we are planning to get (KOSTAL PLENTICORE plus), I watched the whole thing.

One detail stood out to me, which he was quite frustrated about because he hadn’t paid attention to it when buying. It was about the maximum charge/discharge current at the battery input. He mentioned that while he made sure the battery itself had a relatively high limit (I think it was 25A), he overlooked the fact that the inverter has only 13A.

I didn’t fully follow his explanation, but he described the problem as the low current limit of the inverter restricting the battery’s output, which means that only about 2.6 kW instead of 5 kW can actually be delivered. This, he said, might lead to situations where if the washing machine and dishwasher run at the same time, grid power would have to be drawn.

This got me thinking, and I searched online for keywords like “what to consider when buying an inverter” and so on. I also skimmed through some forum threads but couldn’t find any advice highlighting this particular specification anywhere.

Am I fundamentally misunderstanding something?

Could someone here explain exactly what this is about? And are there other specs one should pay attention to as well?

I can well imagine that in our case, loads like this will be drawn quite often, and I would be annoyed if such a small detail caused unnecessary grid power consumption.

Best regards

I have exactly this inverter as well.
The 2.6kW is more than enough for me.
A battery storage system is usually only practical for nighttime use, and I rarely, if ever, exceed 0.4kW then.
Washing machines and other appliances are generally run during the day using solar power.

When it comes to what you can or should expect from an inverter, it’s more about factors like noise level (depending on the location), backup power capability (depending on how concerned you are about outages), efficiency, monitoring options, compatibility with a wallbox (electric vehicle charger), support, and so on. ;-)

But 2.6 kW isn’t even enough for an induction cooktop set to power level P?! Seriously, are common inverters really only able to provide that little?

Tolentino schrieb:

But 2.6 kW isn’t even enough for an induction stove on power level P?! Seriously, are common inverters really that limited?

First, a correction: The Plenticore Plus can provide up to 6.5 kW with a large battery.
I have the "small" 5.1 kWh (kilowatt-hour) battery because it’s simply sufficient, and it has a maximum discharge power of "only" 2666 W (watts).

Basically, it doesn’t make sense to size an inverter or battery for just 60 seconds per day.
Better to size it for 12 hours overnight.
In the last 5 months, I bought 10 kWh (kilowatt-hours) from the grid, which cost at most about €3.
So getting a larger or different inverter and/or storage just doesn’t make sense.
Although last night around 6 p.m., while cooking, there were still 2 kW (kilowatts) coming from the solar panels and 2 kW (kilowatts) from the battery, so it’s only really a "problem" if you cook very late with a very high power demand. ;-)

RotorMotor schrieb:

I have exactly this inverter myself.
The 2.6 kW (3.5 hp) capacity is more than enough for me.
A battery storage system is practically useful only at night, and I rarely ever exceed 0.4 kW (0.5 hp) during that time.
Washing machines and similar appliances are usually run during the day using solar power.

When it comes to an inverter, the desirable features are more like noise level (depending on location), backup power capability (depending on fear of outages), efficiency, logging options, compatibility with EV chargers, support, etc. ;-)

If even you say that’s enough, there’s probably not much better out there (you’re already very active in this area and seem knowledgeable).
Does the Kostal score well in the other points you mentioned?

I have to say, I still find that capacity quite low. Usually, we eat dinner late, so Tolentino’s comment hits home even more. I realize that you really have to try to change your habits and “reprogram” them. Both of us work long hours, so all the major appliances have typically been running in the evening or at night… Kudos to programmable dishwashers and washing machines; the new ones will definitely be able to handle that.

RotorMotor schrieb:

First, a correction: The Plenticore Plus can handle up to 6.5 kW with a large battery.
I have the "small" 5.1 kWh (kilowatt-hours) battery because it’s simply sufficient, and it only allows a 2666 W (watts) output power.

That’s exactly the point—the calculation in the video was based on this inverter, which is technically 6.5 kW, but at 13 A (amperes). And he somehow suggested that this is where the catch lies.
Could the battery voltage of 200 V (volts) have something to do with this?