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Idle Consumption: Is It Standby or Overhead?

forbin

forbin

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Jul 4, 2022
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Simple question.

If an inverter has 100W idle consumption, and the other loads amount to 4000W during peak hours, then:

A) During peak hours, total consumption is 4000W. At night, when there are no other loads, minimum consumption is 100W. In this case, idle consumption is standby.

B) During peak hours, total consumption is 4100W. At night, when there are no other loads, minimum consumption is 100W. In this case, idle consumption is overhead.
 
Yes, but I would consider the consumption be turned into Efficiency once you have any loads. Technically you don't have an Idle once you have any loads. If you have an efficiency of 90% at 4000w, then you are burning 444w due to efficiency loss, but I wouldn't call this idle.

Not sure if thats what you were already getting at.
 
Its not that simple. There are 2 categories of loss or inefficiency. First, the electronics & microcontroller which is relatively constant. Second is the loss within the power electronics of the inversion process. This is usually expressed as percentage of the load and can vary by a few percentage points depending on the amount of load.
I would agree that at 0 load the minimum current draw is accurately called STANDBY. Once a load is attached and the inverter is working, any power not being used by the load is really all OVERHEAD.
 
My AIMS 12,000w inverters have a 200w idle (each) and list 88% as their peak efficiency in the specs.

In a year I get....
18,000kwh of PV power IN per my Midnite Classic charge controller metrics.
15,000kwh of consumed power OUT per cheap ebay power meters on the output of my AIMS.
This is 15,000/18,000 = 83.3% efficiency.

For the sake of discussion, let's say the battery charge/discharge + other is 1.7% loss which leaves a round number of 85% efficiency. This means that 2,700kwh of the 18,000kwh of PV were lost at the inverter / year.

Now.... In a year, the AIMS are on for 5,500hrs (1 is on 1/2 that time, both are on the other 1/2) that's 2,250hrs * 200w idle + 2,250hrs * 400w idle = 450kwh + 900kwh = 1,350kwh of idle.

This implies...
1) 1350/2700 = 50% of my losses are idle power consumption.
2) 1350/2700 = 50% of my losses are due to conversion losses.
 
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Lt.Dan said:
Yes, but I would consider the consumption be turned into Efficiency once you have any loads. Technically you don't have an Idle once you have any loads. If you have an efficiency of 90% at 4000w, then you are burning 444w due to efficiency loss, but I wouldn't call this idle.

Not sure if thats what you were already getting at.
Click to expand...
Ultimately, the question I'm trying to answer is, do I need to add panels to account for idle consumption? I like EG4's new 6000EX AIO, but it has high idle consumption in the 130W range. If I run it 24 hours, that works out to 3120Wh. That means I'd have to dedicate 2 or 3 panels just to satisfying the idle draw, which is awful since I only have room for 16 panels total.
 
forbin said:
Ultimately, the question I'm trying to answer is, do I need to add panels to account for idle consumption? I like EG4's new 6000EX AIO, but it has high idle consumption in the 130W range. If I run it 24 hours, that works out to 3120Wh. That means I'd have to dedicate 2 or 3 panels just to satisfying the idle draw, which is awful since I only have room for 16 panels total.
Click to expand...
Yeah, most of the systems people post about here basically need their own solar array just to power the electronics, it's pretty disgusting.
 
forbin said:
Ultimately, the question I'm trying to answer is, do I need to add panels to account for idle consumption? I like EG4's new 6000EX AIO, but it has high idle consumption in the 130W range. If I run it 24 hours, that works out to 3120Wh. That means I'd have to dedicate 2 or 3 panels just to satisfying the idle draw, which is awful since I only have room for 16 panels total.
Click to expand...
Per my post above.... Ultimately I get 15,000kwh of useable power / year from a 12,825kw PV array. If you include wire losses from PV to charge controllers in addition to battery and inverter losses - the overall loss of the whole system is 18% or so. Idle is one component - in my case 1,350/18,000 = 7.5%.

I don't view an overall 18% loss in the whole system as abnormal, it is what it is in each case. So yes - you need to add panels and/or more efficiency and/or larger battery bank till you achieve the consumable power thru-put you want. In my case, I view the glass as 80% full rather than 20% empty :)
 
OffGridInTheCity said:
Per my post above.... Ultimately I get 15,000kwh of useable power / year from a 12,825kw PV array. If you include wire losses from PV to charge controllers in addition to battery and inverter losses - the overall loss of the whole system is 18% or so. Idle is one component - in my case 1,350/18,000 = 7.5%.

I don't view an overall 18% loss in the whole system as abnormal, it is what it is in each case. So yes - you need to add panels and/or more efficiency and/or larger battery bank till you achieve the consumable power thru-put you want. In my case, I view the glass as 80% full rather than 20% empty :)
Click to expand...
Forgive me, I'm new to all this. I went through your post but didn't quite connect all your math dots. Here's what I am expecting. My array size is 7280W (16 x 455). On a good day, I get 5 solar hours, which works out to 36.4 kWh/day. I'm sort of expecting overall system loss (Sun -> PV; PV -> Charger; Charger -> Battery; Battery -> Inverter; Inverter -> Load) to be around 30%, so my usable power would be 36.4 * 0.7 = 25.48 kWh/day. If my AIO is using 3120W of idle, then it is using about 12% of my total usable power. That's ghastly.
 
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forbin said:
Forgive me, I'm new to all this. I went through your post but didn't quite connect all your math dots. Here's what I am expecting. My array size is 7280W (16 x 455). On a good day, I get 5 solar hours, which works out to 36.4 kWh/day.
Click to expand...
Let's say you get 36kwh/day from the PV. At overall loss as in my system, that's 36kwh * .8 (e..g 80%) = 28.8kwh consumable power out of the inverter.

forbin said:
I'm sort of expecting overall system loss (Sun -> PV; PV -> Charger; Charger -> Battery; Battery -> Inverter; Inverter -> Load) to be around 30%,
so my usable power would be 36.4 * 0.7 = 25.48 kWh/day.
Click to expand...
Sun -> PV - I won't put this in with other losses. Sun -> clouds/weather/(smoke from wildfires) is not the same kind of loss as inverter losses, it's weather and you have no control. I'd start with something like PVWatts - https://pvwatts.nrel.gov/pvwatts.php - and see what PV you are likely to get at the charge controller based on your arrays size, angles, and time of year. And then go from there as far as losses. 15% - 20% are realistic.
The one thing you can control is to use large enough wire from the Solar Panels -> Charge Controller to keep losses low as in <2%.

forbin said:
f my AIO is using 3120W of idle, then it is using about 12% of my total usable power. That's ghastly.
Click to expand...
It's not 3,120w of idle, it's 120w of idle :)
 
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FWIW. As mentioned idle power is overhead. Some inverters have a standby/eco/pulse mode which is say down at 2W. Checks for load every 30s but the load has to be decent, normally a % of the rating. Doesn't work with most electronics as they don't present a load initially. Only works for me on an old fridge that uses timers and thermistors.

Also just did a quick test on HF & LF inverters with 2 loads;

HF
Idle = 23W
600W load
Overall efficiency = 91%
Less idle = 94%

1300W load
Overall efficiency = 88%
Less idle = 90%

LF
Idle = 57W
600W load
Overall efficiency = 85%
Less idle = 94%

1300W load
Overall efficiency = 85%
Less idle = 89%

The LF uses an EI transformer so poor idle. I have another with a toroid that idles at 17W but haven't tested.
 
Lilikoi_Heavy_Industries said:
Yeah, most of the systems people post about here basically need their own solar array just to power the electronics, it's pretty disgusting.
Click to expand...

Can inverters be inverter-type or similar? Our inverter-type 8 cu. ft. AC fridge is rated at 85w; I always catch it drawing 50w max, sometimes 0w.

An 100w idle/standby draw is too much.
 
Call it Idle power or overhead power it’s really just operational power consumption.
 
I just add the idle/standby/whatever into my base load calcs.
Don't overlook the fact that inverters have a sweet spot, and are terrible when operated at low loads
 
forbin said:
Ultimately, the question I'm trying to answer is, do I need to add panels to account for idle consumption? I like EG4's new 6000EX AIO, but it has high idle consumption in the 130W range. If I run it 24 hours, that works out to 3120Wh. That means I'd have to dedicate 2 or 3 panels just to satisfying the idle draw, which is awful since I only have room for 16 panels total.
Click to expand...
If more panels was the only sacrifice it might be an easier pill to swallow but the reality is that about 18 of those 24 hours of power consumption are being provided by the batteries.
 
OffGridInTheCity said:
It's not 3,120w of idle, it's 120w of idle :)
Click to expand...
120w operating continuously for an hour yields a 120wh consumption. Over 24 hours, that would yield 2.88kwh of power consumption.

I don't think smiley faces excuse willful ignorance/similar if that was your intent. I'd never use an inverter that wastes so much power.
 
Lilikoi_Heavy_Industries said:
120w operating continuously for an hour yields a 120wh consumption. Over 24 hours, that would yield 2.88kwh of power consumption.

I don't think smiley faces excuse willful ignorance/similar if that was your intent. I'd never use an inverter that wastes so much power.
Click to expand...
The intent was to "gently" correct the idea that a GroWatt inverter actually uses 3,120w / hour of idle power.

It's not strange that an inverter would have 120w idle power consumption. It's partly a function of how large the inverter is and price plays a role as well. My AIMs12,000w inverters idle at 200w but in return the price was OK and I get 240v@50a of power.

This forum (to me) is about sharing info to help people research/choose but also respecting what people choose.
 
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Imagine being a utility and having to have all those extra megawatts generated to overcome all the losses through the grid o_O

I really wonder what kind of efficiency the utility grid actually runs. Even if it was 95% (I doubt it but I could be wrong), that's still a huge amount of watts lost.
 
SparkyJJO said:
Imagine being a utility and having to have all those extra megawatts generated to overcome all the losses through the grid o_O

I really wonder what kind of efficiency the utility grid actually runs. Even if it was 95% (I doubt it but I could be wrong), that's still a huge amount of watts lost.
Click to expand...
Interesting question! - quick google search - https://cogeneration.pro/energy-losses-and-inefficiencies-in-the-traditional-power-grid/
1664380390043.png
According to this it's more like 68% loss overall! But of course this is just one article / viewpoint.

But it already makes me feel better about my ~20% overall system losses with my Solar.
 
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