Selecting a good inverter

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M1kkel

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Nov 16, 2019
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Hello

I have build a 48V 20KwH battery, i got 32x250W panels on the roof.

I have a really hard time locating a good quality 3 phase inverter or 3x1 phase.

I've looked at MPP PIP, but it seems like its buggy, AND consuming a lot of power when its idle. I live in Denmark, where its dark for a long time in october to March. So i was hoping to find a better product, without paying 8.000 USD. I've looked at Victron, but it seems like they are extremely expensive.

Have anyone here, something to recommend?

Thanks

BR Mikkel
 
You dont find any cheaper.
Is your plan offgrid or hybrid? Ie being able to sell back to grid?

Hybrid MPP products or clones you have to calculate around 6-80w idle load per phase. Ye its a lot. I live in sweden and run it so i know :)

If you want to get lower ie 40w per phase or even lower you have to pay. Hybrid cost alot more also than offgrid. Both in purchase and in idle draw.

You cant have the cake and eat it at the same time :)
 
My plan is NOT to sell to the grid, so an offgrid inverter is actually what I need.

God any suggestions, for something better than MPP??

6-80 watt idle, how is it not 80watt all the time, that was how I understood it at least 😎
 
M1kkel said:
My plan is NOT to sell to the grid, so an offgrid inverter is actually what I need.

God any suggestions, for something better than MPP??

6-80 watt idle, how is it not 80watt all the time, that was how I understood it at least 😎
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I'm 100% off-grid. I use AIMS 12,000w 240v (US 2 legs of 120v) and it runs about 200w/hour idle.... except that I don't let it be idle. Its turned on (automatically) when the battery (14s lithium ion) hits 51.5v and I'm ready for the house to consume power from it and off when the battery hits 49.5v and the house reverts to grid via ATS. The on/off voltages are adjustable so I can control the max DOD on the battery.

I don't have any idle time... but I do have (DC->AC) conversion losses. I'm running 14% overall loss to the system - most of that is due to AIMS inverter losses I believe.

So I'd say there's 2 issues - idle and conversion loss. I've take care of idle but I'd have to buy something like a Magnum to do better on conversion losses.
 
offgridinhecity.. even though you dont run it idle the unit still pulls that :=)

60-80w. Depens on the type. Not 6w. sorry :)

Victron is better but it cost more but you can get below 40w internal use. Dont forget that MPP and others have an efficiency between 80-90% meanwhile victron and others generally are above 90%. Also a factor tho think about.

Neither less as you know in our area we dont hav emuch sun in winter so make sure you have enough panels! I have max 5% output from the solar panels during the winter. That doesnt even cope with self consumption of the system :)
 
daromer said:
offgridinhecity.. even though you dont run it idle the unit still pulls that :=)
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I'm willing to listen - but that's not what my numbers say.

The AIMS has a peak efficiency of 88% per documentation. When I have a constant load on both legs of AIMS (when it on), the overall percentage of loss drops to 14% - e.g. AIMS is likely at 85% efficiency and system is loosing 1% - something like that. That's based on overall kwh out/consumed (from AIMS) divided by kwh in (as reported by Midnite Classic). An operating efficiency of 85% out of 88% peak (specs) sounds like I'm getting full efficiency I'm only loading the inverter it at the 40-60% level and so it not in 'peak' operating range.

When I don't have a load on 1 leg, the idle is 100w/hour and if no load on either leg it goes up to 200w/hour - and the overall efficiency (kwh out / kwh in) drops to low 80s% indicating loss to idle..... the drop is significant... which is why I believe its due to idle and that idle is not there when a load is active.

Remember that I have the AIMS configured as 'plain inverter' - e.g. the ATS / charging functions are disabled (its an option) so its not doing any 'sensing' of incoming AC loads or anything like that. Its a straight-thru DC-> AC power with no other operations going on.
 
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The inverters Always uses a set Number of watts to drive the unit. Loaded or not loaded doesnt matter. IF you want to calculate true efficiency you retract those Numbers but for most People its better to include Them. Cheap Manufacturers Always removes Them to get higher overall Numbers for efficiency ;)

Instead of calling it Idle load call it self consumption. Its There No matter of the load.

And you can test it. With known resistive load :) but beware of that efficiency differ alot based on the load. On mpp its alot. :)
 
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I'd like to understand things better because at this point, I'm confused about the meaning of "Idle consumption".

Let me start with this - measuring kwh in to the battery vs kwh out downstream of the inverter - I'm get a high of 86.1% efficiency. For every 100kwh in from the PV array I'm consuming 86.1kwh in the house. The inverter is the largest loss but not the only one.

Losses in that 13.9%.....
1) The Batrium shunt shows 48w draw with everything on except the inverter.
2) Charge/Discharge of the lithium-ion has a small loss
3) General wiring etc losses.
4) *Inverter*

Let's say that the at its best - the inverter itself the source of a 13% (of 14%) loss for the sake of argument. It can be as high as 19% and as low as 13% depending on the load.

So... you are saying, that even in the best case - the 13% loss is partly due to 'idle consumption'. I think the issue I'm having is that I thought 'idle consumption' was separate from DC->AC conversion losses - and that its the inverter logic such as (in AIMS case) probing for grid for charging/ATS switch-overs and things like that.

Here's the AIMS 'Idle Power Consumption' table from the docs.....
1611620019021.png

What you're saying is that the 200w shown in the table above for "Power Saver Off" mode of the 12K is occurring weather there's a load or not so the actual DC->AC conversion loss % is "loss - 200w"? If I did "Power Saver On" mode, then this should drop to 40w and I might see hgher than 86.1% effeciency?

This is potentially a big deal because the AIMS ran for 5,493hours in 2020. 5,493hours * 160w savings = 878kwh that I potentially lost thru 2020.

I sent an email to AIMS tech support on this - will post what they say if they respond :)
 
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Yes correct. The unit will always pull a certain amount of energy to keep itself running. This is true but there is also some things to consider like when utilizing the unit the self consumption can vary. Lets say you have 100W self consumption in the base this could potentially be lower or higher depending on a couple of factors.

With that said people call it idle because you only see it when "idle" or having very low usage like if you pull 20watt you get 120w usage :D
Thats also why many inverters efficiency is higher at higher load.

I have roughly 200+w self consumption for my system and on daily useage i can see this neither less i run 500watt or 5000watt. If i add upp the efficiency i can still see those 200ish watts lost :D

I think people call it differently i mean those used watts they cant magically dissapeara just because you load the machine right :D

Example but stupid. You walk.. You need xx energy to walk.. You carry something you then need xx energy + yy energy to carry the stuff. Its not like you stop walking just because you carry the things right? :D
 
Got a reply from AIMS on this topic.....

My question: When the inverter is actively producing power from DC battery, with a load on both 120v legs of 30% or higher, is there any loss to 'idle power consumption'? I'm getting 86% efficiency with 30-50% load - and that seems perfectly normal? (e.g. no loss to idle - but loss to DC->AC conversion).

More Info:
I have them configured in 'straight DC->AC' mode - e.g. they are not hooked to incoming AC or doing charging or ATS ing. My system turns them on/off automatically for use - e.g. they never sit with 'no load'. They are not in power saver mode - they are in regular mode.

1611709619100.png
 
@M1kkel OK, you can see that AIMS is around 86% efficient with 200w or 40w idle consumption :)

Back to your original question. The 'most efficient' inverter series I've read about is MagnaSine. They claim up to 96% efficient. Not sure about 3 phase option.
 
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daromer said:
offgridinhecity.. even though you dont run it idle the unit still pulls that :=)

60-80w. Depens on the type. Not 6w. sorry :)

Victron is better but it cost more but you can get below 40w internal use. Dont forget that MPP and others have an efficiency between 80-90% meanwhile victron and others generally are above 90%. Also a factor tho think about.

Neither less as you know in our area we dont hav emuch sun in winter so make sure you have enough panels! I have max 5% output from the solar panels during the winter. That doesnt even cope with self consumption of the system :)
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Exactly - but you are using victory now, is that correct ?

I was quoted for a 250/100 victron mppt charger, 3x multiplus II 3000/48 and a fox display for 25.000 dkk.
However it doesn’t seem the charger is able to deliver to both battery AND inverters. How did you solve that?

the mpp-pip can be turned off in the winter months, is saw you write that in another post. BUT will it still consume idle power, if it’s just delivering ac via. The grid?

growatt will need 3 batteries if I parallel 3 units. That’s really dumb.
 
OffGridInTheCity said:
>the mpp-pip can be turned off in the winter months,
If it helps you - I have an MPP-PIP in my cargo trailer -> camper conversion and put in a switch to 'bypass it' when the trailer is not in use - to avoid idle issues. Here's my thread on this - https://secondlifestorage.com/index.php?threads/trailer-disable-pip-for-long-term-storage.10142/ and out of that - here's the switch/circuit.....
View attachment 23583
Click to expand...

Okay - so doing it the hard way.
thanks for this, this is really great.

so you also have a pip in your house?
 
M1kkel said:
so you also have a pip in your house?
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In the house I have dual AIMS 12,000w inverters for a total of 24,000w (the blue boxes in my ID photo to the left). I also have Midnite Classic Charge Controllers, APC UPSs, etc - separate pieces of equipment. The PIP is all-in-one - Charge Controller, Inverter, AC Charging, UPS.
 
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