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
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
RotorMotor schrieb:
That’s nice in principle. The only question is how long the field really stays in P mode?
In our case, if at all, it’s only for a short time because the water boils very quickly and everything else burns in P mode.
And then there’s the question of how much power it actually draws. Ours, for example, is 3.2 kW. I just checked, it seems to be 4.5 kW, not 7.5 kW. At least that’s something.
But base load plus 2x 1-1.5 kW (my estimate for setting 7-8) already pushes the limit. And for pasta with Bolognese sauce, it’s not just 3 minutes but about 15 minutes of pasta (with 3 minutes in P mode beforehand) and at least 30 minutes for the sauce.
I’m not saying this is a disaster that will bankrupt anyone. But it definitely weakens the self-sufficiency promise that is communicated by the providers if you have to buy electricity from the grid every day.
Having a larger battery that you wouldn’t realistically drain given its capacity doesn’t make much sense either.
Yes, the answer to @Nixwill2’s question would be interesting—whether another inverter could handle this better.
I really need a smart meter so I can analyze our daily and night base loads.
Nixwill2 schrieb:
Or choose an inverter that delivers more power. Is that available, or is Kostal actually well positioned here?
Are you generally satisfied with your technology? Would you buy something different today? Personally, I don’t know a single brand in this field; the ones I mentioned are standard with house manufacturers. As I already wrote here, I have no idea. Since yesterday, besides Kostal, I have occasionally read about Fronius, so I just looked at the datasheets.
The hybrid inverters seem to deliver 25A starting at 6kW (e.g., SYMO GEN24 6.0 PLUS). More precisely, it states:
max. usable input current (Idc max MPPT1 / MPPT2): 25A / 12.5A
max. usable input current (Idc max): 22A
I don’t know what the MPPT values mean, but I assume it is more than with the Kostal inverters, or should you consider the 12.5A? 🤨
EDIT:
For Kostal, however, the specifications consistently state for all sizes:
max. input current (Idc max) per DC input
R
RotorMotor25 Aug 2022 09:15Tolentino schrieb:
But base load plus 2x 1-1.5 (my estimate for level 7-8) already pushes the limit. And with pasta Bolognese, it’s not just 3 minutes but about 15 minutes for the pasta (plus 3 minutes pre-boil) and at least 30 minutes for the sauce.If you constantly put over 2kW into your sauce, it will either burn or splatter on the ceiling. ;-)Tolentino schrieb:
I’m not saying it’s a disaster that will bankrupt you. But it certainly reduces the self-sufficiency promise communicated by the providers if you have to buy energy every day.Well, in my opinion and that of most others, you lose more Wh because of the somewhat slow/inexact regulation than from the 2.6kW limitation. But that one percent of self-sufficiency is completely negligible compared to the energy you must buy for the heat pump in winter.
Tolentino schrieb:
I urgently need a smart meter to analyze our day and night base loads.Is it possible to read your meter with an IR head?Nixwill2 schrieb:
Or choose an inverter that delivers more power. Is that available or is Kostal actually well positioned here?There are options, for example the mentioned Fronius can deliver more power, but Kostal is well positioned as I described. A PDF showing power outputs depending on battery can be found on the manufacturers’ websites.
Nixwill2 schrieb:
Are you generally satisfied with your technology? Would you buy something different today? Personally, I don’t know of any brand in this field; the ones I mentioned are standard with the home builder.Overall, I’m satisfied. It could be somewhat quieter. When you close the door, you don’t hear it anymore, but then the technical room gets quite warm. Backup power would be nice right now, and I find it a pity that Kostal doesn’t support it at all.
Although many other inverters only have one socket or require effort to switch over.
RotorMotor schrieb:
I would currently appreciate having backup power and find it unfortunate that the Kostal inverter does not support this at all.
I have the same inverter and at some point, I believe at the end of last year, I read that they planned to release a capable device "soon." However, so far, nothing seems to be available.
RotorMotor schrieb:
Is it possible to read your meter using an IR head?No idea, can you tell from the meter?RotorMotor schrieb:
Currently, I would also appreciate backup power and find it unfortunate that the Kostal system cannot provide it at all.How often would backup power actually be needed?
We recently experienced a 3-hour period when our inverter didn’t work because there was no supply from the grid. However, those 3 hours wouldn’t justify an upgrade costing around 5,000 euros.
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