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Home Forums General Discussion Electric appliances off-grid

This topic contains 3 replies, has 2 voices, and was last updated by  elnav 7 years ago.

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  • #36679

    elnav
    Member

    At first the idea of electric appliances in an off grid house seems like a contradictioe

    However careful measurements using a power monitor that measures total consumption reveals that some countertop cooking appliances are far better than electric stoves and in some cases even better than propane or wood stoves.

    In summer time a propane or wood cook stove adds undesirable heat to th edwelling interior. Electric cooking appliances will minimize the amount of heat added to the kitchen and by actual measurement consume less power than a typical solar PV array produces. In places where a generator is needed periodically to drive a deep well pump of 300 feet or deeper, cooking time and water pumping can be combined into one operation thus making better use of fuel burned by necessity.

    #40798

    Kathleen
    Participant

    I believe that if you use electric appliances that generate heat that is an awful big draw on your system. We have a small, affordable system and I would never even consider that. Even a bread machine can only be used for mixing and kneading not baking. My wood cook stove is used all year long and I am not really so concerned about heating my house up, as it would heat it up about the same with an electric stove (which I personally do not like for cooking). Most everyone I know would never give up their microwaves. Possibly they would be efficient, but we don’t use them due to the fact that we feel they are not safe from a health standpoint.

    Now electric refrigerators is another matter. We are going to be adding the Sundanzers to our household within the next year.

    #40803

    elnav
    Member

    I’m basing my comments on power consumption measurements using a P4400 meter and some practical experiemnts by Marshall at http://www.genverters.com

    High peak demand for short periods still does not amount to a lot of kilowatt hours. But then again the conventional wisdom was you could not run air conditioners on inverters. Good thing Uncle Sam didn’t know that, because I worked for a company that sold 124 systems for military patrol boat use.

    four years later we still haven’t seen a failure.

    Please excuse my ignorance. I have only been designing off grid systems for 8 years so I guess I still don’t know much. I began in alternative power back in the mid seventies designing wind turbine controls

    #40804

    elnav
    Member

    Kathleen I just finished browsing your website. Your battery bank is equal to what Marshall has (www.genverters.com) and may be even better depending on previous use. You said “I believe that if you use electric appliances that generate heat that is an awful big draw on your system”.

    Yes and no. Your trimetric meter isn’t telling you the whole story. Look up the P 4400 ‘Kill A Watt’ meter to see what I am talking about. It is selling from Amazon for around $20

    Your Trimetrix measures whole system performance but the P4400 measures each individual appliance. It is much more accurate.

    The reason why I concluded a bread maker is quite energy efficient is because it is an enclosed small compartment and it does not vent heat into a room the way conventional ovens do. If you plot the actual power consumption curve minute by minute you can see how the power draw only occurs at discrete periods with lots of no load period in between. The yeast rises as much from residual heat as it does from active heat input. Even during the baking cycle the heater element is not energized for the full time period and when it is active it is a smaller element than a regular ove uses.

    A conventional oven uses a 3000 watt element to heat a comparatively large volume but the bread maker does not. It has a very closely controlled heat input.

    My measured consumption of a Hitachi brand bread maker for the whole 4 hour 10 minute cycle is 0.078 kilowatt hour. Some recipes take less. Last time I checked NY state electricity rates you were paying just under 20 cents per kilowatt hour. So if you were grid connected you would have paid less than one tenth of 20 cents per loaf id powered from the grid. From looking at your solar panel array it appears you can generate in the neighborhood of 300 watts per sunhour. 3.5 hours around noon would give you 1 kilowatt hour of charging. Adding all the available sun hours at your location my guess is you can get roughly 2 kilowatt hours per full day of sun for your particular panel so consuming 0.078 kilowatt should not be such a drain.

    since you are hand washing the laundry in small batches, feeding horses, and drawing water your work day is pretty full. Sometimes a labor saving device can be a real boon.

    I lived in Ontario close to upstate New York for a quarter century at approximatel the same latitude so I think I am familiar with your climate.

    I first became acquainted with power measuring meters like the Trace Line logger when I worked as an applications / Sales engineer for Xantrex.

    But the P4400 is way better.

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