So, I know inverters have been tested by the end user with no load and compared per product, but when are they ever really going to be in idle with no load for any significant amount of time? When the inverters are working with a load, how can we assume the tested idle power is wasted or added into the working power? For example, let's say for a 1000w load, each inverter is working and the tested consumption of each inverter is, let's say 1050w. 1000w for the load, and 50w working loss or whatever...so where is the idle power at this time? I'm just curious about this and trying to wrap my head around it.
Something I'm not getting about inverter idle consumption...
- Thread starter jfharper
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Dinobot248
New Member
From my understanding the idle power is what is required to run the inverter. It should exist regardless of whether the inverter is idle or not. The idle power consumption is outside the scope of the inverter. In other words, it does not know that it is consuming that power.
It's can be difficult to measure. I measure mine by disconnecting the AC input and only at night when there is no solar. Solar has its own small inefficiencies that I don't want to blend in.
Get a clamp meter and measure the current going through one of the large battery cables. Your inverter will tell you how much load it's providing. Simply do the math
Clamp current 20A x 53v = 1060 watts
Inverter is supplying the house load of say 900 watts. Power drawn from battery is say 990w so the power required by your inverter to run is about 70w. The efficiency conversion of DC to AC is 900/990 or about 90%. This is a simplified example.
At very low loads, efficiency takes a nose dive so you need to really measure the loads at a meaningful about like 50% of inverter capacity.
I don't need an exact number and measure it when there is a stable house load like 1000 watts.
It's can be difficult to measure. I measure mine by disconnecting the AC input and only at night when there is no solar. Solar has its own small inefficiencies that I don't want to blend in.
Get a clamp meter and measure the current going through one of the large battery cables. Your inverter will tell you how much load it's providing. Simply do the math
Clamp current 20A x 53v = 1060 watts
Inverter is supplying the house load of say 900 watts. Power drawn from battery is say 990w so the power required by your inverter to run is about 70w. The efficiency conversion of DC to AC is 900/990 or about 90%. This is a simplified example.
At very low loads, efficiency takes a nose dive so you need to really measure the loads at a meaningful about like 50% of inverter capacity.
I don't need an exact number and measure it when there is a stable house load like 1000 watts.
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Warpspeed
Solar Wizard
A high idling power is like driving your car with the handbrake partly on.
Its a continual loss you can well do without.
Its a continual loss you can well do without.
MurphyGuy
It just needs a bigger hammer
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Idle load is in addition to any loads being powered. There is a small drop when a load is powered, but its irrelevant. If your inverter has a 100 watt idle, and you put a 1000 watt load on it, you'll probably be using 1095 watts.. (1000 + 95)..
High idle loads are the mark of cheaply designed inverters, and they add up fast.. 100 watts x 24 hrs = 2.4kWh of energy wasted.
High idle loads are the mark of cheaply designed inverters, and they add up fast.. 100 watts x 24 hrs = 2.4kWh of energy wasted.
wopachop
New Member
Good question i wonder if the idle load changes at all. I think i could test it with a wifi 120v meter and a space heater.
Will see what it pulls on regular shore power. Then see what it pulls off my inverter. Then find out what my idle draw is with no load. Manual claims 1.0a for my 12v 1000watt Renogy inverter. I know the space heater changes slightly as it warms. Will bounce back and forth between outlets several times. Or maybe use a battery charger with constant current.
Will see what it pulls on regular shore power. Then see what it pulls off my inverter. Then find out what my idle draw is with no load. Manual claims 1.0a for my 12v 1000watt Renogy inverter. I know the space heater changes slightly as it warms. Will bounce back and forth between outlets several times. Or maybe use a battery charger with constant current.
wopachop
New Member
Renogy 1000w inverter.
Shore power sagged to 119.4v under load and pulled 520watts.
Inverter sagged to 117.3v and pulled 513w.
The inverter at that time was using 529.44 w.
Turned everything off and idle load is 5.78w. (lower than expected....is there maybe stored power in capacitors?)
Waited 10 mins idle draw is down to 5.36w.
edit: this doesnt answer the question huh? Need to know the inefficiency of the inverter itself. Would those numbers say the inverter is running at 96% efficiency at 500watts?
Shore power sagged to 119.4v under load and pulled 520watts.
Inverter sagged to 117.3v and pulled 513w.
The inverter at that time was using 529.44 w.
Turned everything off and idle load is 5.78w. (lower than expected....is there maybe stored power in capacitors?)
Waited 10 mins idle draw is down to 5.36w.
edit: this doesnt answer the question huh? Need to know the inefficiency of the inverter itself. Would those numbers say the inverter is running at 96% efficiency at 500watts?
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Tomthumb62
Solar Wizard
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In our use case, we have lots of time that the inverter isn’t powering any loads, because the inverter mostly is there just to power the fridge. So we switched from a 2000w inverter to a super efficient Victron 1000w. Our idle draw has dropped about 10 fold, from 540Wh to 60Wh per day. Our max surge load is about 800W, the Victron can do 2400W.
Dinobot248
New Member
Capacitors don't last but a couple of seconds at the very most. If you consider Victron the leader in this area, their 48v 1200VA (about 1000w) has an idle consumption of 10w.
It's very difficult to see any other company / brand beat Victron's number.
It's very difficult to see any other company / brand beat Victron's number.
Hedges
I See Electromagnetic Fields!
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Inverter efficiency data curves or tables, when given, tend to show a fixed (idle) power consumption, plus additional consumption proportional to the square of the power delivered.
That makes sense since power dissipated in a resistor (such as inductor or transformer windings, and MOSFETs) W = I x R^2
For larger inverters, more dissipation but could be less per watt of rated output. How do Victron's bigger inverters compare?
SMA Sunny Island, 48V 5750W idle consumption 25W.
There is some amount of power for the computer and analog electronics. Then there is driving gate capacitance of MOSFETs and hysteresis loss in magnetic cores.
That makes sense since power dissipated in a resistor (such as inductor or transformer windings, and MOSFETs) W = I x R^2
For larger inverters, more dissipation but could be less per watt of rated output. How do Victron's bigger inverters compare?
SMA Sunny Island, 48V 5750W idle consumption 25W.
There is some amount of power for the computer and analog electronics. Then there is driving gate capacitance of MOSFETs and hysteresis loss in magnetic cores.
The larger victron inverters have pretty low idle power specs, although I've seen quite a few posts on the victron forums about the actual idle power being significantly higher than the spec sheet indicates.
Aridom82
Learning addict
You can put one of these to see how much power you are using. Then you turn off everything and the figure it shows will be the idle consumption.
timselectric
If I can do it, you can do it.
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My system is never idle.
Idle consumption is no concern for me.
Efficiency losses are a different story. But that's only an issue for small systems.
Idle consumption is no concern for me.
Efficiency losses are a different story. But that's only an issue for small systems.
I think my brain absorbed 3 words in that entire post.
Maybe a comparison for one the YouTubers could be setup, Will maybe as he might have all the gear, where he measures different percentage loads on a certain system, like 10%, 25%, 50%, 75% for i.e. 2x6500ex vs Victrons vs 18K system, and measures the power going in and power going out...I guess that would be the efficiency Hedges mentioned, maybe that is too much to ask...but it might shed some light on if the idle is an additional power draw or part of the system on those percentages. Meaning, if the idle draw sort becomes part of the working part of the systems at those percentages, obviously like fan power...fan power at idle is not doing much but at 50-75% is part of the system that perhaps other systems see as well, so the idle loss is less loss and more part of the work.
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Rednecktek
Solar Wizard
Hedges
I See Electromagnetic Fields!
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A little math and graphing in Excel goes a long way.
diysolarforum.com
diysolarforum.com
Won't help with the bulging head, however.
low frequency inverter
IM looking to buy48v 6kw lfi ,how do you justify big idle consumption in this case 150w for 6kw model i see it as disadvantage over hfi. It is 3.6kw per day just for the idle consumption .I will have 16 lifepo4 280ah batteries ,so what would you buy LFI or HFI ?
diysolarforum.com
Help needed - 48VDC system (Skoolie)
The “conversion penalty” at 48v will be quite a bit lower than 15%. For a Victron unit, I can tell you it will be 8% or less. Victrons are top shelf and have demonstrated ~90% efficiency. Anyone want to test their mpp 48 volt all in one unit?
diysolarforum.com
Won't help with the bulging head, however.
