Types of Microwave Ovens

Inverter, convection and standard microwave differences

While the basic technology in microwave ovens hasn't changed for decades, there have been some developments in the last few years, including the integration of cooking sensors and inverter technologies in microwave ovens. Although combination convection/microwave ovens have been available since the 1980s, improvements in convection technology have made combination microwaves much more popular.

With convection technology, ovens use traditional microwave heating and a small fan to circulate heat throughout the oven, a process that aids in surface browning -- a weak spot for microwaves. This enables the oven to produce a roast chicken with crispy, browned skin or fries that are golden and crunchy. Convection cooking also helps food retain moisture. Microwave/convection ovens let you choose which cooking technology you want to use: microwave only, convection only or microwave and convection combined. In convection mode, you can almost use these models like a second regular oven. Though foods won't cook much faster, you can bake, roast and safely use metal pans (only in convection mode). Using microwave and convection together cooks food faster, and you get crispier results than you would by using a regular microwave. Editors at Consumer Reports say that many microwave/convection ovens work very well, and for small dishes, it could save you from turning on your regular oven.

A microwave with a convection feature adds significantly to the price, so if you mainly want to reheat and defrost foods, a standard countertop microwave is more cost effective. Top-rated countertop microwave ovens usually cost about $100 less than comparably sized microwaves with convection.

Inverter technology works to prevent overcooked edges or ice-cold middles in dishes. When powered at 50 percent, conventional microwaves will cook in cycles, cooking at 100 percent for a short time, then not cooking at all for an equal period, then back to 100 percent on high. Microwaves with inverter technology cook the full time at 50 percent power, resulting in better control and reducing cooking times. Inverter microwaves are especially good at defrosting and reheating at lower power, say reviewers.

Despite technology differences in microwave ovens, however, we found similar complaints about durability across the board; several owners complain in reviews that "they don't make them like they used to." Even with more-expensive convection microwaves, we didn't find a correlation between price and reliability. For example, the pricey Kenmore Elite 67909 (*Est. $300), a 1.5-cubic-foot microwave/convection unit, earns good scores in tests for even heating and defrosting ability, but owner ratings from Sears.com are mixed. About half of the two dozen owners are perfectly happy with this model while the other half complains of breakdowns, sometimes within months of purchase.

Panasonic microwaves, especially those models with inverter technology, get great reviews in professional testing, especially for evenness of heating. Reviews in Which? and Choice magazines include testing of Panasonic inverter microwaves; both testing organizations say the technology works especially well when reheating dense foods such as lasagna or a casserole. However, we still found a smattering of complaints about durability. The Panasonic NN-H965BF (*Est. $150) has an inverter defrost function. While most of the 30 owners posting reviews to Amazon.com say it worked perfectly, we found a similar pattern of complaints for this microwave as we did for many others -- some units broke within months of purchase.

To be fair, we found durability complaints about most microwave models, but the sting seems worse when owners have paid extra for convection, inverter technology or for a stylish design. We did find some bright spots in user ratings, however. Quite a few Sharp microwaves get consistently good owner reviews, even though they are not usually particular standouts in professional tests. We found solid user reviews for the mid-sized Sharp R-305KS (*Est. $120) and Sharp R-820JS (*Est. $230), a 0.9-cubic-foot microwave with convection.