Worth it to buy a smaller microwave?

softdown
softdown Solar Expert Posts: 3,901 ✭✭✭✭
Full size units require 1300 watts. Bad enough but it also seems to "shock" cold batteries.

I am wondering if a smaller microwave using about 750 watts would be worthwhile. 

Not going to quit microwaving. Unfortunately I am hooked on the convenience. Though I try not to use it for over two minutes unless the sun is effectively charging the battery bank. 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries

Comments

  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    I've been using a small microwave on solar for several years. It works fine even with modified sine current. Biggest pain is not being able to use a full sized plate in the limited space.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
  • SteveK
    SteveK Solar Expert Posts: 387 ✭✭
    Remember to keep in mind the 1100W microwave uses more like 1500W or VA out the inverter too.

    I had a 700W microwave in our smaller 30A camper. Every time we used it was a let down. Things took forever to cook compared to our other microwaves so were just spoiled. We found it took the same amount of energy to cook meals but the times were way longer. So much longer we decided not to use it so I took it out. We moved to a single burner induction cooktop there instead.


  • SumPower
    SumPower Registered Users Posts: 63 ✭✭
    edited November 2023 #4
    We found that if you use the power setting on a large micro wave and take your time, the food cooks more evenly.
    The total power consumption was about the same between a small micro and the larger one that we replaced it with.
    For example, cooking rice in a glass bowl with a glass lid. We would set the micro to the power setting of 50%, then cook for 15 minutes. So the micro cyles full power for 10 seconds, then no heating for 10 seconds, so it would have full power for three 10 second periods per minute and three 10 second periods of no heating. Then let the dish sit for 5 minutes as a finishing process (simmering). Rice was always fluffy and perfectly cooked.
    Once you get food up to temp. it takes less heating to keep it simmering. 

  • softdown
    softdown Solar Expert Posts: 3,901 ✭✭✭✭
    Thanks for the input. So far nobody has indicated that a smaller microwave would significantly help the battery bank. 

    With all my freezers it becomes difficult to ascertain what exactly caused a significant voltage drop in the battery bank. It fluctuates a lot. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • Graham Parkinson
    Graham Parkinson Registered Users Posts: 168 ✭✭✭
    Just as a side note to all this - Inverter type microwaves such as the Panasonics actually draw less power when on lower power settings instead of turning on and off like conventional microwaves do to modulate power delivery.   This way you can have a larger microwave, still run on lower power draw and fit larger plates in.

    Offgrid in cloudy PNW

    Full Schneider system with 18 REC 420W panels, 100A-600V controller, XWPro, Insight Home, six Discover AES Rackmount 5kW batteries, Slimline enclosure, Lynk II, AGS, H650,  H2200, H3000 (with Gen Line 2 wire AGS on AC1), Kubota 4500, Onan 7500 (on second AGS and AC2).

  • SumPower
    SumPower Registered Users Posts: 63 ✭✭
    Thanks for posting Graham, had no idea that there was an inverter microwave on the market. Researched by googling "inverter microwave oven", and they are supposed to use up to 15 to 17% less power.
    Cooked for several years in Latin America and the only appliance we had was a microwave, so this makes it quite interesting for replacement microwave ovens.
  • SteveK
    SteveK Solar Expert Posts: 387 ✭✭
    edited November 2023 #8
    The inverter microwave sounds like a decent solution. Should bring the otherwise ~35% efficient cooker up to 50%. Thanks. Inverter tech saves us a ton of energy in our basement dehumidifier.
  • JRHill
    JRHill Registered Users Posts: 353 ✭✭✭
    edited November 2023 #9
    I didn't know of inverter MWs until this thread.

    I just recently replaced our 10 year old microwave as it was obviously degraded it took a minute+ longer to reheat a coffee, etc. than it did years back. We are anally conservative with power draw and when the MW performance deteriorated it drew the same amount of power while running. If the power draw degraded with run time I wouldn't not have been an issue vs run time.

    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
  • scrubjaysnesttoo
    scrubjaysnesttoo Registered Users Posts: 5
    SteveK said:
    Remember to keep in mind the 1100W microwave uses more like 1500W or VA out the inverter too.

    I had a 700W microwave in our smaller 30A camper. Every time we used it was a let down. Things took forever to cook compared to our other microwaves so were just spoiled. We found it took the same amount of energy to cook meals but the times were way longer. So much longer we decided not to use it so I took it out. We moved to a single burner induction cooktop there instead.


    I changed ours to 1100 watt, draws 60 amps on the inverter input while running. 
  • SteveK
    SteveK Solar Expert Posts: 387 ✭✭
    SteveK said:
    Remember to keep in mind the 1100W microwave uses more like 1500W or VA out the inverter too.

    I had a 700W microwave in our smaller 30A camper. Every time we used it was a let down. Things took forever to cook compared to our other microwaves so were just spoiled. We found it took the same amount of energy to cook meals but the times were way longer. So much longer we decided not to use it so I took it out. We moved to a single burner induction cooktop there instead.


    I changed ours to 1100 watt, draws 60 amps on the inverter input while running. 
    Sounds about right for a 24V system.
  • softdown
    softdown Solar Expert Posts: 3,901 ✭✭✭✭
    Just seen that eggs do better if cooked at a lower temp. Seems a smaller microwave would have the same effect. Not going to constantly fiddle with my power settings. I keep forgetting the close the skylights until it gets weirdly chilly. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries