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Comment by elil17 | Hacker News Reader

Rtings has a post saying that they aren't effective: https://www.rtings.com/microwave/learn/research/microwave-in...

Curious to hear more about your personal experience

Read that and got to this ludicrous claim:

> The inverter models are marginally better at converting the total power they draw from an outlet (the apparent power) to useful work (the active power). However, your residential electricity bill is calculated based on active power use, so an inverter microwave won't save you any money.

If any power company has the ability, much less the inclination, to not charge you for your appliances waste heat that would be news to me.

I’m trying to figure out how they misinterpreted things to come up with that statement. Maybe they are mixing up start-up draw and constant draw? Idk

Yeah, I have no idea. The article was published in late 2024, maybe they used a late 2024 LLM to help write it? Seems like the sort of confident-but-obviously-wrong mistake that was common back then.

Power factor is the only thing that makes any kind of sense to me. Utilities don't typically bill you for bad power factor unless you're an industrial power consumer.

I don't know offhand what the power factor of a microwave looks like, but I bet it's not great. I can see an inverter style having better power factor.

Wow that's wild. I usually consider Rtings pretty reliable so that's a big surprise to me.

This is referring to active vs reactive power and the concept of power factor [1]. You're still paying for all the real energy consumed (including waste heat). Inverter microwaves tend to have a higher power factor than traditional models (measured data [2]). Residential electricity bills are based on active energy (kWh), not apparent power or reactive components, so a better power factor by itself doesn’t lower your bill. We’ll take a look at the article to clarify it.

[1] https://en.wikipedia.org/wiki/Power_factor [2] https://www.rtings.com/assets/pages/hRDTskis/power-factors-l...

Okay, this is a new concept for me so mind if I try explaining it to confirm I understand?

Inverter microwaves have an actual power consumption that more closely resembles what you see at the wall. Non-inverter microwaves will appear to draw more power from the wall than is actually delivered to food, but it doesn't matter that much, because that "extra" power is stored inductively in the magnetron, which gets returned to the grid when the microwave shuts off. There are some minor conversion losses from this, but not nearly as great as one might initially think looking at wall vs radiated power.

Is that correct?

Could they be talking about power factor? Still doesn't make sense anyway.

I've found inverter microwaves for example useful when making porridge. A traditional one at 50% power blasting at full for 5 seconds makes it boil over, but on an inverter microwave 50% continuous heats it evenly and consistently such that it doesn't boil over. Sure you may be able to lower the traditional one so it does it even shorter steps but then it takes longer to get done or the result might be rather poor due to the inconsistent heating steps.

I also could never get traditional ones to heat potatoes well. Scalding hot on the outside, cold on the inside. With inverter ones it's simpler: just a lower power setting for longer.

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