HF vs LF Inverters: What is better in 2025? (Migrated posts)

[Norwasian]

Evidently it is an HF inverter. Their documentation says it could support a maximum of a 4HP motor, which is about 3KW.

That's what I like about the LF inverters--they can actually start motors equal to their rating, with up to triple their rating possible for surge capacity. This 5kw inverter claims to be able to surge to 125% of its capacity for about 5 seconds before halting output. If one is not running motors, it might be an awesome product. For myself, I've gotten to where I focus solely on the LF inverters, preferably toroidal.

 

[Zwy]

Evidently it is an HF inverter. Their documentation says it could support a maximum of a 4HP motor, which is about 3KW.

The 10Kw ASP will start a 5 hp single stage compressor on a single inverter and that was on one 120V leg. I couldn't get it to start the 5 hp industrial shop air compressor but think the compressor unloader may not be working correctly.

I run 2800W of lights constantly all day with the 2 ton mini split heat pump running full bore while starting motors all day long. I run the welders off the ASP units. I've ran the mini split with lights on and turned on the 2 ton central air in the shop that does not have soft start with no problems running the pair in the shop.

I'm impressed so much I bought 3 more for $2800 with DDP shipping. 2 will be replacing the LV6548's in my house and the remaining unit will be a spare unless I decide to use it in the shop. I do think 3 units will easily start the shop air compressor.

Load testing videos are in my Shop Build thread.

That's what I like about the LF inverters--they can actually start motors equal to their rating, with up to triple their rating possible for surge capacity. This 5kw inverter claims to be able to surge to 125% of its capacity for about 5 seconds before halting output. If one is not running motors, it might be an awesome product. For myself, I've gotten to where I focus solely on the LF inverters, preferably toroidal.

I have a LF inverter that can start some motors but found the sustained load will overload the inverter causing shutdown.

Like I said, I start motors all day long in the shop using the SRNE ASP's and not a single issue. The air compressor in the shop has a recorded surge of 141A. It doesn't surprise me it didn't start it. The compressor would start turning but couldn't get up to speed running off just PV and batteries, no grid assist. I did start it with Mixload seting which is grid assist easily.

 

[timselectric]

Evidently it is an HF inverter.

That's were the market is trending. And what most people want.
Lighter, smaller, more efficient, and less expensive.
You couldn't give me a LF inverter, for free.

Edit:
Actually, a member did give me one for free.
It's in the basement, collecting dust.
A whole lot of shit would have to hit a bunch of fans, for me to pull that heavy thing out.

 

[Norwasian]

I have a LF inverter that can start some motors but found the sustained load will overload the inverter causing shutdown.

Just to make sure I understand this correctly, are you starting a motor on an LF inverter that is rated for the same or less wattage as the inverter is rated? E.g. are you starting something like a 6HP motor on a 5kw inverter, and finding that the inverter will run the motor, but cannot sustain the motor for long durations? What is the inverter rating, and what is the motor's wattage and/or HP rating?

Like I said, I start motors all day long in the shop using the SRNE ASP's and not a single issue. The air compressor in the shop has a recorded surge of 141A. It doesn't surprise me it didn't start it. The compressor would start turning but couldn't get up to speed running off just PV and batteries, no grid assist. I did start it with Mixload seting which is grid assist easily.

That 141A of surge could possibly be handled by a 5kw LF inverter (should be about 125 and 136 amps of surge, nominally). If it is actually a 5HP motor, the inverter should be able to sustain it if not heavily loaded by other devices as well. But is this the motor that your LF inverter will start yet not sustain long-term?

I'm all in favor of hearing good reports on HF inverters, such as this one Will is promoting. But where I am located, for what is on the market here, I still don't trust the HF ones. I've had positive experiences with the LF variety, and have heard rather negative reports of the other. Here on the forum, I have seen virtually no complaints about LF inverters--but this can certainly not be said of their HF counterparts.

That's were the market is trending. And what most people want.
Lighter, smaller, more efficient, and less expensive.
You couldn't give me a LF inverter, for free.

Edit:
Actually, a member did give me one for free.
It's in the basement, collecting dust.
A whole lot of shit would have to hit a bunch of fans, for me to pull that heavy thing out.

It doesn't sound as if you've given the LF inverter a fair trial. If you haven't used it, what makes you dislike it....its weight alone?

Most things of greater weight have greater value.

If I were near you, I'd be happy to take it off your hands for the same price as you received it.

 

[timselectric]

It doesn't sound as if you've given the LF inverter a fair trial.

Life isn't fair.

If you haven't used it, what makes you dislike it....its weight alone?

I fixed it (why it was free) , tested it , and put it away.
I figured that I would use it for something. But it hasn't met the needs of any situation, yet.
"Lighter, smaller, more efficient" (free was less expensive lol)

Most things of greater weight have greater value.

Only when they're valued by weight.
In this market, weight has a negative impact.

 

[Norwasian]

In this market, weight has a negative impact.

Perhaps this is true for you, but it is not so for me. I look at the weight and the greater the better. More weight means more than just having a good amount of copper in a transformer. It can mean having a superior-quality aluminum heat sink. It can mean having larger, more durable, cable connectors. The shrouding itself is of better quality if it's not merely a thin tin-can ready to cave in at some unexpected bump.

When it's too light, I look elsewhere.

Why should the weight of an inverter be such a drawback for you? You'll only lift it when installing it...it's not something you'll have to deal with every day. Some favor those new styrefoam-type (can't remember their actual material) "concrete" blocks that are so much lighter weight and used for home construction, too: I'd take the traditional heavy blocks for my wall any day--something sturdy and able to support my toroidal inverter mounted to it--and not melt in the event of a fire.

 

[Mattb4]

My experience with LF versus HF is the HF work fine within their rated output. LF will start heavier surge items easier but it comes at a cost of less efficient operation. The LF may have lower idle draw than HF but many have lower efficiency during operation. The old LF inverters were built like tanks and last darn near forever but they lack refinement and easy user setup with access to features. It is like the old joke about you can have your choice of Ford Model T color. That is if your choice is black.

Been using SRNE based AIO's for ~3 years now. There are ongoing reviews of all the ones I have operated available here at the Forum. No failures but some quirks and things I would have wished were different.

Nearing my 2 year update for my Powmr 24vDC 3kW unit (SRNE). It has been doing its thing for so long that much of the time I pay it no attention at all.

 

[42OhmsPA]

On the topic of weight, I'll take light LiFePO4 over heavy Lead Acid all day long; maybe that's what I like light HF inverters. Heavy lead is great for other things....

 

[timselectric]

Why should the weight of an inverter be such a drawback for you?

Because I'm not getting any younger.
I don't want to lift it today. And definitely won't want to lift it in the future for repairs or to upgrade.
But again, it's not just the weight. It's the combination of all downsides.
Physical size is a big one.
Everyone will need to decide what is best for them. Based on their needs, space available, and budget.
There's nothing wrong with either option. They both can get the job done.
Just pick which one works for you. That's what I did, after years of research.
Only you can know what will accomplish your goals.

 

[Zwy]

Just to make sure I understand this correctly, are you starting a motor on an LF inverter that is rated for the same or less wattage as the inverter is rated? E.g. are you starting something like a 6HP motor on a 5kw inverter, and finding that the inverter will run the motor, but cannot sustain the motor for long durations? What is the inverter rating, and what is the motor's wattage and/or HP rating?

It was a 12V inverter, smurf blue color and I could start a refrigerant compressor that required 2400W to start but had to use 2 batteries. The problem was after it was started, the inverter would shut down. It had exceeded the inverter rating by 200W sustained.

That 141A of surge could possibly be handled by a 5kw LF inverter (should be about 125 and 136 amps of surge, nominally). If it is actually a 5HP motor, the inverter should be able to sustain it if not heavily loaded by other devices as well. But is this the motor that your LF inverter will start yet not sustain long-term?

I never said that. You assumed it. A pair of Quattros may not start that air compressor, I have other loads running while the air compressor might start which is how I tested it. The pair of SRNE ASP's actually start the compressor, it just won't hit full speed. 3 SRNE ASP's might, I have a spare but I had planned from the beginning to run the air compressor from grid power.

The ASP's run other 5 hp motors however. I show in the second load testing video just one ASP started a 5 hp single stage air compressor on just one 120V leg with other loads running on the same 120V leg. I have a Miller Trailblazer portable welder generator that could only start that same air compressor on 240V.

I might someday look at the shop air compressor unloader. I own a 15 hp 3 phase compressor and the unloader for it doesn't release until the motor is at full speed.

I'm all in favor of hearing good reports on HF inverters, such as this one Will is promoting. But where I am located, for what is on the market here, I still don't trust the HF ones. I've had positive experiences with the LF variety, and have heard rather negative reports of the other. Here on the forum, I have seen virtually no complaints about LF inverters--but this can certainly not be said of their HF counterparts.

HF is the way to go from my experience. Technology keeps advancing and the future will be HF. I don't like to spend too much on inverters as I can replace it and not be bothered by initial cost. This is why I'm replacing the LV6548's in my house. Low initial cost and I can move to a higher capacity inverter that would provide both 120V legs if one inverter went down.

It doesn't sound as if you've given the LF inverter a fair trial. If you haven't used it, what makes you dislike it....its weight alone?

It couldn't power the loads I needed to run.

Most things of greater weight have greater value.

If I were near you, I'd be happy to take it off your hands for the same price as you received it.

No, you wouldn't. I'm trying to decide what I should do with it. I could use it if needed until a LV6548 goes in my work trailer but after that, I don't really have a use for it as I have much larger HF inverters that handle the loads here.

 

[Zwy]

Perhaps this is true for you, but it is not so for me. I look at the weight and the greater the better.

So you drive a Class 8 truck for a daily driver instead of a car. Is it easy getting in/out of parking spaces? How about the fuel mileage? The Class 8 will go well over a million miles, those cheap light cars might not make it to 100K miles.

You must use lead acid batteries and not LFP. I could go on with more examples.

Heavier is better until it isn't.

 

[Mattb4]

My PowMr 10kW (SRNE ASF model) in the last few days has run my Sears 120v radial arm saw even when it bound up at one point and needed clearing, a 5 gallon 120v 150psi air compressor, My Makita worm drive 7-1/4 inch saw (it really has a startup surge), My cement mixer and the well pump this morning to build some solar array bases. A drill press and assorted grinders and never once did it seem to bother the ASF. Now most of these are run one at a time (household loads were likely only the refrigerator and some minor stuff) but since there is just one of me I do not find that limiting.

I will say this about inverters, the more capacity of batteries you have the more likely the inverter will pull up to its rating. Nothing chokes an inverter quicker under load than DC voltage drop off. Good cables are also a must.

 

[WorldwideDave]

Does this all-in-one inverter support charging batteries during specific Time Of Use grid provider plans (SoCalEdison)?

 

[Norwasian]

So you drive a Class 8 truck for a daily driver instead of a car. Is it easy getting in/out of parking spaces? How about the fuel mileage? The Class 8 will go well over a million miles, those cheap light cars might not make it to 100K miles.

You must use lead acid batteries and not LFP. I could go on with more examples.

Heavier is better until it isn't.

I can only afford to have one car...so it's a 4WD sturdy Toyota, and its mileage is poor. So, you're mildly close on that one. But, I just pulled a KIA wagon out of a steep ditch on a remote mountain this week with it, and I often need its capabilities when traveling around here in rainy season. I'd take the Toyota any day over a modern electric car--at least, for my circumstances.

I used to use the lead acid, and still likely prefer them over AGM, but I've moved on to Lithium. That said, the 48-volt LiFePO4 battery that I purchased had a shipping weight of over 110 kg / 242 lbs. That's not light. For those wanting a 20-pound inverter in place of an 80-pound unit, but then accepting a 250-pound battery for it, I say focusing on the inverter's weight sounds a bit hypocritical.

I guess one thing that bothers me is that the HF inverters are essentially guilty of false advertising. They claim to provide X kilowatts of power, but this is only true of non-inductive loads. Put a motor on it, and it often only supports a third of that rating. For this reason, it's unfair to compare HF and LF inverters which are given the same rating. At the same rated wattage, an LF inverter would knock the socks off an HF inverter, in terms of output--but it would be correspondingly more expensive, bulkier, etc.--all the features that some here discount/dislike. Get an HF inverter and an LF inverter which both start and run the same inductive load and one may see far less difference between them in terms of size and price. But the LF inverter will outlast its HF counterpart, and will lengthen the life of the motors it supports as well.

One gets what one pays for. An "inexpensive" inverter that must later be replaced just got more expensive.

 

[WorldwideDave]

I truly wish inverter numbers were more honest as well. But then again, BMS ratings are a similar issue.
Inverter example: I had a 2000W Renogy inverter that couldn't start a 1300W pump. current protection overload I guess inside the inverter. That inverter cost $500. Bought a $270 Giandel inverter also rated for 2000W, and can run 2000W constantly for 4+ hours at a time, and easily start a 1300W pool pump every time with zero issues, 7 days a week for the past year straight.
BMS example: Battery says '100A BMS', but that is surge/peak. The BMS handles that fine. Battery manufacturer/specs say '50A continuous', but after 35 minutes, it reaches 70 degrees C inside the battery, and BMS will not cut out. If I keep going, it will just melt the wires. The BMS never stops based on current or heat, only voltage. So while I can run the .2C rated cells at way above their charge or discharge rating running a 100A load for hours, I will melt the wires, bloat the batteries, and the BMS will never shut it off. That's terrible (CHINS battery, FYI - replaced BMS with JBD 7 months ago).

 

[timselectric]

You can't really put all HF inverters in a pile. Just like you can't put all LF inverters in a pile. The advertized numbers don't always match the truth.
But that's usually the fault of the vendor/rebrander.
My HF Growatts do output what they claim. But they are straight from the manufacturer. (No rebranding, advertisers)
A single 5k unit will (and has) start(ed) everything on my property.
The two hardest loads are a 3 ton A/C , and a 7hp air compressor.
I started with only one, to beat the hell out of it. And make sure they were capable of doing what I needed. It impressed me enough to build my system with them. The first one (that I throughly flogged) has been running for 3.5 years so far, without a hiccup. I don't know how long they will last, but I know that I will get more than my money's worth out of them.

 

[Will Prowse]

You can't really put all HF inverters in a pile. Just like you can't put all LF inverters in a pile. The advertized numbers don't always match the truth.
But that's usually the fault of the vendor/rebrander.
My HF Growatts do output what they claim. But they are straight from the manufacturer. (No rebranding, advertisers)
A single 5k unit will (and has) start(ed) everything on my property.
The two hardest loads are a 3 ton A/C , and a 7hp air compressor.
I started with only one, to beat the hell out of it. And make sure they were capable of doing what I needed. It impressed me enough to build my system with them. The first one (that I throughly flogged) has been running for 3.5 years so far, without a hiccup. I don't know how long they will last, but I know that I will get more than my money's worth out of them.

Absolutely. And there's tons of LF inverters that are pure and utter garbage. Everyone seems to forget about those. You can usually tell which LF inverter is good by the idle consumption. The lower the idle, the more time they worked on the software and usually everything else.

 

[42OhmsPA]

I guess one thing that bothers me is that the HF inverters are essentially guilty of false advertising. They claim to provide X kilowatts of power, but this is only true of non-inductive loads. Put a motor on it, and it often only supports a third of that rating.

Please provide some examples.

 

[Norwasian]

Please provide some examples.

The forum has many of these, some in this thread already. A 10kw inverter should produce 10,000 watts of power. Comparing to horsepower (HP) as motors are often classified, according to my dictionary:

Two common definitions used today are the imperial horsepower as in "hp" or "bhp" which is about 745.7 watts, and the metric horsepower as in "cv" or "PS" which is approximately 735.5 watts. The electric horsepower "hpE" is exactly 746 watts...

In any case, one horsepower is approximately 3/4 of a kilowatt. So a 10kw inverter should produce about 13.4 horsepower--which should suffice to start and run a 13HP motor.

Do you know of any 10kw HF inverter able to do this?

 

[OpenNRG]

In any case, one horsepower is approximately 3/4 of a kilowatt. So a 10kw inverter should produce about 13.4 horsepower--which should suffice to start and run a 13HP motor.

You aren't allowing for "Start Up" Watts. Start Up Watts can be 3-4x Running Watts.

 

[Will Prowse]

The forum has many of these, some in this thread already. A 10kw inverter should produce 10,000 watts of power. Comparing to horsepower (HP) as motors are often classified, according to my dictionary:



In any case, one horsepower is approximately 3/4 of a kilowatt. So a 10kw inverter should produce about 13.4 horsepower--which should suffice to start and run a 13HP motor.

Do you know of any 10kw HF inverter able to do this?

Yeah but the locked rotor amps required to start any motor are substantially more than their continuous duty requirements after it's rotating. Lf inverter will always be able to supply more inrush current for the coils. That's a fact and no one here is arguing that.

At 8kW HF 12kpv can start a 5 ton ac. Not bad. Without softstarter.

HF inverters are where the market is headed. Why are they not using an LF inverter on Tesla vehicles? They are starting and stopping a electric motor thousands of times per minute. Why are they using a liquid cooled HF inverter circuit? If they are running a motor, why don't they follow your advice and use an LF?

Maybe you should tell all these tesla engineers that they are ridiculous for their decision. You should show them how it's done.

What is a new LF inverter coming to market that you are excited about?

 

[Will Prowse]

If an HF inverter is properly sized, you can run any electric motor on the planet. If you have proper cooling and good design, you can do it for decades. Just because LF has inherently more current for motor start up doesn't mean that the market is going to continue to make them.

 

[Norwasian]

You aren't allowing for "Start Up" Watts. Start Up Watts can be 3-4x Running Watts.

But a 10kw toroidal LF inverter can handle a 3x surge. That's the point. HF can't even handle the running wattage, much less the surge.

Yeah but the locked rotor amps required to start any motor are substantially more than their continuous duty requirements after it's rotating. Lf inverter will always be able to supply more inrush current for the coils. That's a fact and no one here is arguing that.

At 8kW HF 12kpv can start a 5 ton ac. Not bad. Without softstarter.

HF inverters are where the market is headed. Why are they not using an LF inverter on Tesla vehicles? They are starting and stopping a electric motor thousands of times per minute. Why are they using a liquid cooled HF inverter circuit? If they are running a motor, why don't they follow your advice and use an LF?

Maybe you should tell all these tesla engineers that they are ridiculous for their decision. You should show them how it's done.

What is a new LF inverter coming to market that you are excited about?

A 5-ton AC unit is equivalent to 6.5HP, which translates to about 4850 watts. Your 12-kilowatt inverter had better be able to run that! An LF inverter could run much better than that.

I've seen some nice LF inverters. Victrons are the ones I'm looking at right now.

 

[Will Prowse]

But a 10kw toroidal LF inverter can handle a 3x surge. That's the point. HF can't even handle the running wattage, much less the surge.


A 5-ton AC unit is equivalent to 6.5HP, which translates to about 4850 watts. Your 12-kilowatt inverter had better be able to run that! An LF inverter could run much better than that.

I've seen some nice LF inverters. Victrons are the ones I'm looking at right now.

No that's not true, because the LRA is going to be higher. thats not 4,850W. It can be 4X higher. That's what my reply said. Motors require a massive inrush to get things moving.

I just said it's a 8kW inverter. It's not 12. That's the name of the inverter. It's not the output. The 12 is how much solar it can handle. That's why I mentioned both.

 

[Will Prowse]

But a 10kw toroidal LF inverter can handle a 3x surge. That's the point. HF can't even handle the running wattage, much less the surge.


A 5-ton AC unit is equivalent to 6.5HP, which translates to about 4850 watts. Your 12-kilowatt inverter had better be able to run that! An LF inverter could run much better than that.

I've seen some nice LF inverters. Victrons are the ones I'm looking at right now.

You could use a small inverter and run a large ac but it would require a soft start. That's also why I mentioned that in my example.