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Microwave Ovens with Inverter Technology Really Cook

by on October 28, 2009
in Health and Home, Kitchen, Guides & Reviews, Time Savers
Rating: 5 Stars 

kitchen with microwave ovenIf you’re like most of us, your microwave oven serves two main duties: boiling water and reheating leftovers. But wouldn’t it be great if rather than just taking up a chunk of space in your kitchen, you could actually rely on your microwave for cooking meals?

Cooking food successfully in a microwave is challenging because the magnetron, the element that cooks the food in most microwaves, can only deliver full power. Even when set to “50% power”, the microwave oven is actually going through cycles of delivering 100% power, followed by a period of no power.

Imagine if your regular oven worked this way! Instead of cooking a roast at 350 degrees, you’d cook it at 700 degrees for ten minutes, then take it out for ten minutes, and repeat over and over again until the meat is cooked. Good luck with that!

The Microwave Inverter Solution

inverter vs. conventional microwavesPanasonic and GE have microwave ovens on the market with something they call “inverter” technology, which aims to solve this problem. The inverter modulates the level of energy being transmitted by the oven to achieve a consistent level. So when you set 50% power, for example, you actually get a steady stream of 50% power for the entire cooking time. The result is more evenly cooked food, defrosting without cooked edges, and even the ability to keep foods warm until mealtime.

Update 6/13/13: Whirlpool AccuWave and KitchenAid Optimawave ovens use the same technology.

Panasonic NN-SD688SWe spent a few weeks with Panasonic’s NN-SD688S, a 1.2 cubic foot counter top model with 1300 watts, to see how it worked out. Using recipes from Panasonic’s site, including some produced by the prestigious Culinary Institute of America specifically for inverter microwaves, we made hollandaise sauce, fruit crisp, corn chowder, barbecued pulled pork and some other fun dishes.

What we found was that the microwave inverter performed surprisingly well for dishes that required slow cooking in moist environments, such as the hollandaise sauce (which can be tricky to do on the stove top) and pulled pork. Corn chowder worked fine as well, though it would have been just as easy on the stovetop and we didn’t like moving large bowls of boiling liquid in and out of the oven. Perhaps not surprisingly, the fruit crisp was a flop, with a soggy, raw-tasting topping and overcooked fruit underneath.


Based on our experiences, we could easily see using an inverter microwave in addition to our standard cooktop and range, especially during busy holiday times when we are trying to cook many dishes at once, while also keeping everything warm until serving time. It is a fast and clean way to steam vegetables, melt chocolate, braise meats or do any one of a number of occasional kitchen tasks that involve steady cooking and do not require browning.

So if you are purchasing a microwave, we recommend that you give inverter models strong consideration. All Panasonic models also recently received the Good Housekeeping Seal, which provides a two-year limited warranty against defects.


Where to Buy

Panasonic Inverter microwave ovens: Buy Now at

Whirlpool AccuWave microwave ovens: Buy Now on Best Buy

KitchenAid Optimawave microwave ovens: Buy Now on Best Buy


UPDATE 6/24/17: With Whirlpool and KitchenAid no longer making inverter models, Panasonic is the remaining brand of choice for this technology. The Panasonic NN-SD945S was our recent winner in our Best Microwave Oven review. Read the article to find out why and learn about our opinion on whether Panasonic's new "cyclonic wave" inverter oven technology is worth the extra cost.

How to Make Microwaves Even Better

(An open call to manufacturers)

Our experiment with microwave recipes, even those written specifically for Panasonic inverters, clearly revealed another long-standing design flaw with all microwave ovens. It turned our initial attempt at crumbled bacon for the corn chowder into charcoal, and curdled our first run of hollandaise. The culprit is the nonsensical decision to use a scale of “1” to “10” to set the power level, rather than setting a specific wattage.

This abstract power scale becomes a significant issue with microwave recipes because it requires the cookbook author to assume a certain wattage in developing the recipe (often 800 watts, sometimes not). However, microwave ovens vary significantly in wattage, from around 700 watts to about 1400 watts. So a 700-watt oven will take approximately twice as long on “High” as a 1400-watt one to provide the same amount of cooking. To compensate, the cook needs to convert those times for her own oven based on its wattage.

But this assumes the cook knows what the original wattage was when the recipe was written and the wattage of her own oven. And if you don't know your wattage, don't bother looking on the oven. Amazingly, many manufacturers don't even print the wattage on their ovens! Talk about trying to make things difficult for cooks! Algebra with unknown variables is not something that should be required in the kitchen...

The solution to this is simple, however, and just requires one manufacturer to make the common-sense leap forward to allow all of their ovens to be set based on wattage delivered. This is the same logic that allows us to set our regular gas and electric ovens to 325 degrees, not “60% of the way around the blank dial”. Microwave recipes could then be written as “cook at 800 watts for five minutes”, which would be easy for a cook to apply for any oven from any brand.

Discussion loading

How to figure out Watt the Hob is going on...

From Greg Gallacci on August 27, 2015 :: 8:56 pm

Calories[or Watts!]: energy required to raise the temperature of some Water by some Degrees during some Time.
Measure out 1 quart of Water, and measure the Temperature. 
Microwave the Water for One Minute at Power setting 1.
Measure the Temperature of the Water again, and note the change in Temperature.
With fresh water, do the same for Power Setting 2, measure the change in Temperature after One Minute.
Once you have this list of temperature changes for each power setting, find the formula that tells you how many Watts it takes to heat up a quart in sixty seconds by the temperature-changes on your list.
This sort of calibration seems crude, but it is a good measure of how much energy your oven actually delivers into water in a minute at each setting.  Microwaves do most of the cooking through the heating of water/moisture.

I am being lazy, not providing equation.

I do agree, a direct wattage setting would be very handy, and be a reliable standard.
“Warm for 5 minutes at 18 Watts/second” would be nice….




From Phil Nielsen on September 29, 2015 :: 11:15 pm

Why, out of the dozens & dozens of co’s making micro-waves, doesn’t at least one make a left hand door model?



How does the Cyclonic Wave CES2015 perform?

From noreen on January 31, 2016 :: 10:31 pm

Hi Josh,

I am buying new microwave. The Cyclonic wave sounds interesting. Have you evaluated it and if so, how does it compare to one with only the inverter tech?



I haven't reviewed directly, but I'm familiar with it.

From Josh Kirschner on February 04, 2016 :: 11:31 am

The cyclonic microwaves use the same inverter cooking mechanics as all the other Panasonic microwaves. The difference is that the cyclonic models claim to distribute the microwaves more evenly within the interior, for more even cooking.

I haven’t tested the cyclonic microwaves side-by-side with the non-cyclonic. If the price difference is relatively small, I would probably opt for the cyclonic model, though either would be a step up from a non-inverter oven.



I don't think it makes

From Sean Smith on April 19, 2016 :: 7:39 am

I don’t think it makes sense to specify a particular wattage because this only applies while the microwave is new. As the magnetron ages with use, its effective power decreases. It might make sense if the decline is predictable and the oven takes this decline into account when displaying the power.



GE Profile with Inversion

From rudy strusinski on June 14, 2016 :: 6:22 am

just replaced old GE Microwave with a new Profile GE.  It was great to be able to adjust the wattage.  It seems more logical having this ability to raise or lower its strength just as we control our stovetop or oven gas or electric.  I am getting the hang easily enough of reheating items that once were problems with chicken or certain meats.  Getting closer to the “Jetson’s” technology.  Cool!




From tryduck on August 23, 2016 :: 12:52 pm

I agree these manufactures need to own up to their products!Along with your “call” I think they should also stop charging outrageous prices for the replacement parts for ANY devices period! WTH good is paying 250 for a MW then the board goes out and the cost for the damn board is 225 when the damn whole MW is only 250…So tired of all this over priced replacement parts BS, if they could make an sell the MW for 250 then they should be forced to divide that 250 up when putting costs on replacement parts!Its no wonder humans waste so damn much, WHY pay 225 for a board for something that you bought BRAND NEW for only 250. Then they got that who “black market” used parts BS where the used part is 215 WTF is wrong with humans and their GREED…If our government should put their nose in things put it in this not healthcare!



In the UK

From Gary Moore on August 31, 2016 :: 7:01 am

Electricq now offer an inverter microwave oven in the UK. the model no is:- EIQMW9BEAINV. It is available from Buy It Direct who are the importers and Tesco.



Bad experience with Panasonic inverter

From jose luis on October 23, 2016 :: 4:18 pm

I am in Spain. I purchased a Panasonic NN DF383 1000W inverter microwave oven, combined with convection + conventional oven.
The inverter part failed after a month of use, had some smoke inside, bad smell and no heating. I took it to the Panasonic Service and got the inverter circuit replaced.
Back home I noticed now it takes much longer to heat food than when new. Made a quick test of power with a measured quantity of water and noting the temperature increase in five minutes and got a result of about 740W instead of the intended 1000W.
A measure of the input power shows normal input power of about 1750W, but it decreases slowly during operation and is only 1300W after 5 minutes heating.
I suspect the Magnetron is defective. I will take it again to Service, but son far it has been a bad and frustrating experience.



Panasonic Inventor

From Owen More on December 13, 2016 :: 9:31 am

Good day

I am owning a Panasonic Micro oven and the service provider indicated that an Inventor(A606Y4V00GP) need to be replaced.

Contact details: 072 280 3725

Advise please.



Inverter or convection microwave

From Carol on December 29, 2016 :: 5:09 am

I want a microwave that bakes, heats through evenly and does small roasts. Should i be looking at inverter or convection model?



Definitely convection

From Josh Kirschner on December 29, 2016 :: 1:08 pm

While an inverter will heat evenly, it will not brown roasts or bake the way a regular over will. For that, you definitely want a convection oven. Some microwaves have convection cooking, as well, or you could get a large toaster oven that offers convection cooking. Our recommendation for the best large toaster can be found here:



Microwave deficiencies

From Sarah on February 17, 2017 :: 5:34 am

Manufacturers are more interested in the latest bells and whistles than being practical.  We need a white (for visually impaired) oven, no sensor cooking, and one that could make it through year one.  We are on our third one with the same warranty, Kenmore from Sears.



Are they cheating with power specifications?

From joseluis on February 18, 2017 :: 8:50 pm

Some manufacturer specifies the MO as 1000W microwave power output, (as written on the plate). But the line Input power is given as 1040W on the same plate. Does it mean that the inverter + magnetron has an astonishing high 96% efficiency?

Not really,they make a biased interpretation of IEC 60705, the Norm to measure the power output of microwave ovens.

We already know the trick: design and specify a product that complies, but only while at the Test Bench… same as certain German diesel engines!

So, this inverter type MO will provide the 1000W output, but only for very few minutes. The time necessary to test according to IEC 60705. After that, they gradually reduce the output power to about 600W. That is what you actually get if you cook for, say, 15 minutes.

Easy to prove: measure the input power and you get initially about 1720W (reasonable for an output of 1000W, efficiency 60%). Continue for 5, 10, 15 minutes and you will see the input power descending to 1050 W - and 600W aoutput power!

And this is legal, they comply with IEC 60705. But you only have 600W instead of 1000!!!

A nice, but very indecent trick, absolutely unmoral that this Japanese manufacturer is using to cheat its trusting customers.




From chuck on April 22, 2017 :: 12:04 pm

Where do I get a replacement for a broken latch.
  model#NN-SN936B OR 946B OR 736B



See if you can repair yourself

From Josh Kirschner on April 25, 2017 :: 11:45 pm

The door latch issue on Panasonic microwaves can sometimes be repaired yourself. Do a Google search on “Panasonic microwave door latch repair” and you’ll see a number of videos showing you how to do it. If it truly is broken, you should contact a Panasonic authorized repair center to get it fixed. They may be able to sell you the part but, more likely, will require you to have them repair it (at a cost that probably won’t be worth it).



what do you think now?

From pam on June 24, 2017 :: 1:47 pm

I’m in the market for a new microwave now.  What are your updated recommendations?



Still recommend the Panasonic

From Josh Kirschner on June 24, 2017 :: 2:41 pm

Hi Pam,

Not much has changed in the microwave market over the past five years. The Panasonic SD-945S is our top pick in our Best Microwave Oven article. Read the story for more detail on why we recommend that microwave over others, including the latest Panasonic “cyclonic” models.




Trying to buy a really great Microwave Oven in place of a regular oven

From Mari on November 01, 2017 :: 8:11 pm

I’m looking for a gift for my kids - they are living in an extremely small place & their oven is a mess.  I’m looking for a microwave oven that will cook (obviously minus burners) like a REAL OVEN -

I’m looking for counter top & something they can take along when they buy a house in the future - so,
something that cooks great & looks great & can be used when they move ..



You need a countertop microwave/convection combo

From Josh Kirschner on November 06, 2017 :: 10:47 am

There are a few models of countertop oven out there that combine a microwave with a convection oven. Cuisinart, Kenmore and Kitchenaid are some of the options (e.g., I haven’t tested any of them and, ideally, they would get better results from a separate microwave and oven, but if space is really tight one of these might work.



Inverter vs Old Amana Radarange

From DENNIS on January 24, 2018 :: 3:58 pm

Back in the 70s & 80s, we had two Amana Radarange microwave ovens which had a system that controlled the pulse timing of the power levels to offer very even cooking. !00% magnatron power was always utilized, but the rapid on-off cycling provided even heat production. On power level “1” the “ON” pulse might have been only one second followed by maybe ten seconds OFF. The rapid cycling of the Radarange did not over cook the edges of food, melted butter eveningly, cooked roasts and whole chickens thoroughly inside and out. If I thought for a minute this new inverter technology even closely compared to the results provide by a 40 year old Radarange, I’d have one in a second. Yes, we are still using both Radaranges. One magnatron replaced in 40 years. Not bad, right? I only wish Amana still made them with newer external designs.



"On power level “1” the

From Davehat on June 29, 2018 :: 5:06 pm

“On power level “1” the “ON” pulse might have been only one second followed by maybe ten seconds OFF”

Microwaves still work the same today.



You're missing the distinction of inverter technology

From Jack on June 29, 2018 :: 5:46 pm

Non-inverter ovens (nearly all except Panasonic) work that way, by pulsing the magnetron on and off. For example, lowest power (10%) would be full power “on” for 1 second, then “off” for 9 seconds. 50% power would be on for 5 seconds, then off for 5 seconds, etc. That’s like putting a fry pan on a high burner for a few seconds, then removing it , then putting back on, etc. to reduce the heat. This is far different from reducing the energy output of the magnetron as an inverter oven does. An inverter oven is like a gas burner which can be turned to low flame, high flame, or anywhere in-between. This offers far more even, uniform, more consistent heat than pulsing between high heat and no heat.




From Leone on April 18, 2018 :: 6:00 pm

Hi I just purchased the Panasonic NN-SF574S microwave because of flatbed and inverter features. We are old school and have never had a microwave before. It fits in a cavity in our kitchen however the manual specifies 15cm airflow on top we have 4cm! We do have the suggested 10cm at back and 5cm on each side…What are the likely consequences of having too little airflow on top? Should I return it?



That's tight, but probably tolerable

From Jack on April 19, 2018 :: 11:53 am

That’s tight, but probably tolerable - unless it’s also convection, which heats the entire oven - not just the food itself. Try it heating water or something for 15 minutes and periodically feel the top. If it’s slightly warm, that’s good. If it’s definitely hot, that’s not.



Too hot, I'm afraid

From Jose Luis on April 19, 2018 :: 2:31 pm

I use the standard oven mode (convection) regularly in my Panasonic 1Kw Microwave.
It gets quite hot everywhere, including of course the top of it. I think it would not work OK with only 4 cm ventilation space on the top, if you use convection in your model.
Not only you may burn something, but also the internal electronics could be damaged, even if not all of it is operating in convection mode. Timer and display always operate and should no be overheated.



Imagine if your regular oven worked this way!

From Davehat on June 29, 2018 :: 4:59 pm


your regular oven DOES work that way.  The heating element only has two settings: On or off.  Once it achieves the desired temperature it cycles off/on/off/on/off/on et cetera.  So that’s just like a microwave that cycles off/on/off/on et cetera.

There’s no difference from an engineering point of view.



That's not an accurate comparison

From Josh Kirschner on July 03, 2018 :: 2:36 pm

Yes, your oven does have a heating element that cycles on and off. However, your oven doesn’t go from room temperature to 500 degrees every time it cycles. The oven will have some variation in temperature, maybe 5-10 degrees between cycles, but that’s it - your food will be cooking consistently at (close to) the temperature you set.

The microwave will cycle between full blast power and no power. And during that full blast cycle, it’s very easy to overcook your food before you even realize it, especially for more delicate dishes.




From Davehat on June 29, 2018 :: 5:05 pm

I regularly cook in my microwave.  Mostly I do steaks and other meats, converting them from raw to medium rare.  They are delicious.

I have also cooked mac’n'cheese and other sauce-immersed items.

Setting the microwave to 20% or 30% gradually raises the food’s temperature and cooks it, in much the same way a slow cooker does.  (Except the microwave does it in 30 minutes instead of 4 hours.)



Problem with my Panasonic micro-wave

From Pierre Parenteau on November 30, 2018 :: 9:27 am

Hi ! I bought the Panasonic Cyclonic Inverter (NN-ST775S) 18 months ago. I have a problem with it. Sometimes, the micro-wave stop after 4 secondes of reheat. After 4 secondes, i heard the sound inside change for lower sound. And then, everything is alright or everything stop and i lost the timer and the hour and i have to reset et reprogram. Somebody know what is the problem ? Thanks.



Panasonic / inverter issue

From Jake on December 15, 2018 :: 12:35 pm

Inverter are not made to rush such power into   the high Voltage DC Diode to graduate the magnitude flux into the magnetron

increasing or decreasing the voltage wattage without loosing the performance of the magnetron… depending on the size of the cooking plate 750W per inch square will be fair to start cooking and auto-transformer will do best to drive and performed those task… unless if the inverter are made in the better quality


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