Hi friends,

I am planning to buy an SPF3000LMV or a Must PV33-6048., 3kW is good enough for me. Both have their advantage and disadvantages. In general, the idle load and the inverter efficiency is my point of concern. Does anyone have a good suggestion what to buy and/or can tell me what the idle load is of a Must PV33-6048.

Tell me what you think.

Thanks Piet de Pad.

2 hours ago, Piet de Pad said:

Hi friends,

I am planning to buy an SPF3000LMV or a Must PV33-6048., 3kW is good enough for me. Both have their advantage and disadvantages. In general, the idle load and the inverter efficiency is my point of concern. Does anyone have a good suggestion what to buy and/or can tell me what the idle load is of a Must PV33-6048.

Tell me what you think.

Thanks Piet de Pad.

Why do you want a split phase inverter?

I would go for this.

MUST 4KW 24V INVERTER 100A MPPT INCL WIFI.

MUST inverter 4KW 24V with 100A MPPT, WiFi, and dual outputs. Smart, battery-optional hybrid power for efficient energy control.

I have the 3.6kW brother to it hooked up to 4.55kWp of panels. The 4kW one depending on the voltage spec of your panels can take about 5.2kWp of panels. 93% efficiency and some 10W idle power consumption if I recall correctly.

4kW is better than 3 as more headroom.

Edited November 26, 2025Nov 26 by Denns

On 2025/11/26 at 1:02 AM, Denns said:

Why do you want a split phase inverter?

I would go for this.

MUST 4KW 24V INVERTER 100A MPPT INCL WIFI.

MUST inverter 4KW 24V with 100A MPPT, WiFi, and dual outputs. Smart, battery-optional hybrid power for efficient energy control.

I have the 3.6kW brother to it hooked up to 4.55kWp of panels. The 4kW one depending on the voltage spec of your panels can take about 5.2kWp of panels. 93% efficiency and some 10W idle power consumption if I recall correctly.

4kW is better than 3 as more headroom.

Hi denns thanks for responding to my message. Can you tell me if some has measured that 10Watt idle load or is that just an estimate.

Edited December 9, 2025Dec 9 by Piet de Pad

2 hours ago, Piet de Pad said:

Hi denns thanks for responding to my message. Can you tell me if some has measured that 10Watt idle load or is that just an estimate.

I dont think anyone really measures that. I think anything under 75W is ok which it most certainly should be. If the manufacturer claims 10W then at worst we could say 3x that so about 30W.

It is not a make a break parameter for people when they want an inverter. They typically care about PV rating, AC out power rating, Passthrough, Surge handling, Battery charging/discharge etc.

7 hours ago, Denns said:

I dont think anyone really measures that. I think anything under 75W is ok which it most certainly should be. If the manufacturer claims 10W then at worst we could say 3x that so about 30W.

It is not a make a break parameter for people when they want an inverter. They typically care about PV rating, AC out power rating, Passthrough, Surge handling, Battery charging/discharge etc.

I agree with what you say but if you look at the effect is has on the backup time with a low load it's dramatic. Fore example considering time between sunset and sun rise say 12 hr and an idle load of 75 what it consumes 12x75=900Wh that is more than 20% of a 5kW battery if you include the losses. So I do believe that idle consumption is an important parameter to know. You are right most people have no idea how these things work and yes they accept it as it is. Thanks for you response

@Piet de Pad @Denns True, the majority of buyers care more about capacity and PV ratings — agreed.

But from a practical off-grid and backup perspective, idle draw has a direct effect on battery sizing and runtime.

If an inverter idles at 60–75W, it consumes ~900Wh overnight. That's not trivial — it's 20–25% of a 5kWh battery’s usable energy. So while manufacturers rarely highlight it, idle consumption is definitely a meaningful spec for real-world performance.

People underestimate idle consumption big time. We brag about 3kW output and 6kW surge, meanwhile the thing is quietly burning half a kilowatt-hour every night doing nothing. At 75W idle(realistic), you throw away almost 1kWh between sunset and sunrise — that’s a fifth of a 5kWh battery gone before you even turn on a light.

So yes, it matters more than most think

On 2025/11/26 at 6:08 AM, Piet de Pad said:

Hi friends,

I am planning to buy an SPF3000LMV or a Must PV33-6048., 3kW is good enough for me. Both have their advantage and disadvantages. In general, the idle load and the inverter efficiency is my point of concern. Does anyone have a good suggestion what to buy and/or can tell me what the idle load is of a Must PV33-6048.

Tell me what you think.

Thanks Piet de Pad.

Back to your original question. I have installed a Growatt SPF3000LMV 24 system with 450ah( 11.5kwh) battery capacity. It is monitored by Solar assistant and a Victron Smart shunt. Solar assistant is not accurate enough to measure idle consumption but the smart shunt is capable of measuring it very accurately. I will ask my client when it will be convenient to switch the output breaker off to measure idle consumption from the battery as his system is off grid. It would be interesting to see what it takes to keep this baby 👶 alive 😉 😀

My two Growatt SPF5000ES when in idle, i.e. AC output disconnected consume around 110W, i.e. about 55W per inverter.
This is as reported by the BMS via SA. I have connected the Battery to PBMS tools as well via the RS232 port and it shows a draw as well of around 110W.

1 hour ago, zsde said:

My two Growatt SPF5000ES when in idle, i.e. AC output disconnected consume around 110W, i.e. about 55W per inverter.
This is as reported by the BMS via SA. I have connected the Battery to PBMS tools as well via the RS232 port and it shows a draw as well of around 110W.

This seems more in line with most inverters. The 10W seems too low for me. Having said this I have worked on 12V 1kW inverters that draw about 15W.

Managed to get the info from my client, off grid, load disconnected Growatt SPF3000LMV 24 system configured to SBU. Asked him to dissconect load and immediately connect the load so the inverter fan can start up dissconect load and take the idle consumption with fan running. Consumption via Victron SmartShunt.

On 2025/12/09 at 11:01 PM, TaliaB said:

Back to your original question. I have installed a Growatt SPF3000LMV 24 system with 450ah( 11.5kwh) battery capacity. It is monitored by Solar assistant and a Victron Smart shunt. Solar assistant is not accurate enough to measure idle consumption but the smart shunt is capable of measuring it very accurately. I will ask my client when it will be convenient to switch the output breaker off to measure idle consumption from the battery as his system is off grid. It would be interesting to see what it takes to keep this baby 👶 alive 😉 😀

Thanks i apreciate it

23 hours ago, TaliaB said:

Managed to get the info from my client, off grid, load disconnected Growatt SPF3000LMV 24 system configured to SBU. Asked him to dissconect load and immediately connect the load so the inverter fan can start up dissconect load and take the idle consumption with fan running. Consumption via Victron SmartShunt.

Thanks that quite a bit when you go to bed. You need at least 15% battery capacity left over in the en of the day to make sure this one will not drain the battery in 7 hours the time you sleep.

On 2025/12/10 at 7:57 AM, Scorp007 said:

This seems more in line with most inverters. The 10W seems too low for me. Having said this I have worked on 12V 1kW inverters that draw about 15W.

I have a must PV18-1012, 1kW single phase 120Vac that one takes around 10Watt when no load.

13 hours ago, Piet de Pad said:

I have a must PV18-1012, 1kW single phase 120Vac that one takes around 10Watt when no load.

Thanks for the info. I have 2 x brick inverters at 12V 750 and 1500W that also run at 8 an 10W under no load.

My Axpert 3kVA used to draw 25W under no load. Still much higher than 10W. I can remember how another member actively disputed this low 25W.

Thanks @TaliaB for the detail readings.

My Deye 5 kW is 95% of the time off grid and it draws 76 to 81W with grid off. What impressed me the most of this inverter is if I switch grid on for the 04h-6h30 period to keep at my set battery level it just draws enough for this puppose and most mornings it will only be 100-200Wh. Some other inverters will charge up to specific level and use a lot more grid before going back to battery mode.

I managed to calculate how much the MUST 3.6kW uses in offgrid mode. About 35 to 40W.