Need Some Advice and Help Kettle

7Hunter9
7Hunter9 Registered Users Posts: 11 ✭✭
in Solar Beginners Corner #1
Hey folks, thanks for this great forum.

I have a question and need some help.

1) Have a 100W Solar Panel, this one:
http://www.renogy-store.com/100W-Suitcase-p/kit-stcs100d.htm

2) Want to use it for a simple Kettle, this one.
http://www.amazon.com/Chefs-Choice-Cordless-Electric-Kettle/dp/B0058VCYUU/ref=sr_1_6?s=kitchen&ie=UTF8&qid=1408063372&sr=1-6

3) The kettle will be used for about 15 minutes per day.
4) The solar panel will get all day sun (Arizona)

What AGM battery should I buy?
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Need Some Advice and Help Kettle

    Hi Hunter, welcome to the forum.
    To be honest and fair to you, you'd be far, far, far ahead in every possible way I can think of - - - - to forget this proposed project and go with a little propane camping stove. Solar definitely has it's place, but this proposed project is not it.
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  • 7Hunter9
    7Hunter9 Registered Users Posts: 11 ✭✭
    #3
    Re: Need Some Advice and Help Kettle

    Thanks Wayne.

    I have several propane camping stoves. Been an outdoors man most of my life :-)

    But I still want to know if anyone can help? Why should I not do this? Expense, weight?

    Sorry I'm just a newbie with solar :-)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Need Some Advice and Help Kettle

    Well let's elaborate.

    The kettle draws 1500 Watts. It is 120 Volts. So to run it you need an inverter capable of producing 1500 Watts. Right there you've got several hundred dollars in expense. Now you need batteries to provide that power, including the conversion loss and self-consumption of the inverter. Well on 12 Volts that's going to be a need for about 150 Amps of current, so you end up needing nearly 600 Amp hours of 12 Volt battery to run the kettle at all, never mind for how long. A single 100 Watt panel will make no headway against that demand. To recharge it you'd need more like 1000 Watts of PV. Yes all that even though the Watt hours would only be 375.

    Or look at it simply (with no losses anywhere): 1500 Watts from 100 Watts of PV means 15 hours of direct, full sun. That doesn't actually happen below the arctic circle really. If you take that 375 Watt hours and divide it by a 100 Watt panel (again ignoring losses) you still need 4 hours direct sun just to be able to 'save up' that much power.

    If you try to do this on a much smaller battery, such as one that can hold 375 Watt hours worth of power (i.e. 125 Amp hours @ 12 Volts) its Voltage will drop drastically when the 1500 Watt load is applied and the inverter will shut down right away.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
    Re: Need Some Advice and Help Kettle
    7Hunter9 wrote: »
    Why should I not do this? Expense, weight?

    Yes, expense, weight, complexity, reliability, maintenance, all to heat a kettle of water.
    Yes, it can be done, but if you're looking at a small system as a learning project, I'd strongly suggest a small system to run a couple of LED lights. Far more affordable and more suited to a small solar system.
    Consider how long you can crank the starter on your car before the battery starts to fade - - that is roughly the power the 1500 watt kettle would try to suck out of your battery for 15 minutes. HUGE compared to a couple of LED lamps.
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  • 7Hunter9
    7Hunter9 Registered Users Posts: 11 ✭✭
    #6
    Re: Need Some Advice and Help Kettle

    Thanks Cariboocoot!

    Yep, for got about the inverter. Newbie!

    So looks like I need to spend a few more bucks on an inverter and more panels.

    Thanks much all.
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #7
    Re: Need Some Advice and Help Kettle

    Can you get by with a 12v appliance intended for truckers, etc?

    While I have cannot vouch for the quality of the products or retailer itself, I didn't know that such things like a 12v microwave even existed, let alone 12v contact cookers.

    I only present this here as representative of stuff I found, but cannot vouch for!

    http://www.roadtrucker.com/catalog/12-volt-kitchen-1.htm

    While the amperages on many devices are high, it is offset by cooking times well less than an hour, minutes in some cases. Still, you are looking at a hefty agm battery like a big Odyssey or Optima, and if all you are doing is making an 8 minute solar breakfast, this may be do-able.

    Note that I have not done all the math on each of these things to see if they are feasible with only a 100 watt panel to recharge, so don't buy anything without doing the power budget homework! Unless you do, some of these would be an, um, recipe for deficit-charge. :)

    I was just blown away seeing a 12v microwave. Who knew?

    Now that I think about it, due to Peukert, even with a large battery most of this is intended to be used with the truck engine / alternator running. So perhaps a small 12v coffee-maker might be worth looking into and not the major cooking appliances.
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #8
    Re: Need Some Advice and Help Kettle
    7Hunter9 wrote: »
    Thanks Cariboocoot!

    Yep, for got about the inverter. Newbie!

    So looks like I need to spend a few more bucks on an inverter and more panels.

    Thanks much all.

    Or, downsize your kettle to THIS.
    Paul
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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #9
    Re: Need Some Advice and Help Kettle
    waynefromnscanada wrote: »
    Hi Hunter, welcome to the forum.
    To be honest and fair to you, you'd be far, far, far ahead in every possible way I can think of - - - - to forget this proposed project and go with a little propane camping stove. Solar definitely has it's place, but this proposed project is not it.
    Yep. Much cheaper and easier ways to heat water.

    A twig-powered rocket stove and/or a propane burner is the answer to the OP's question.
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #10
    Re: Need Some Advice and Help Kettle

    Well just for the sake of the argument, changing times and all. Lets look at a lithium solution.

    Almost all of the premises of the conventional half ton solution for this scenerio, are fundamentally altered using a battery tech that can deliver high currents in a small package.

    OP Kettle: 1500W.
    1500W inverter.
    12v system.
    Required draw: 150A DC.
    Example Battery capacity: 60Ah [1]
    LiFePo4 max discharge rate :6C conservative
    Battery weight: 6kg
    Actual discharge: 2.5C
    Battery DOD: 80%
    Run time for kettle per charge: 20min
    Solar required per charge per day: (assuming 3kWh/kWp) 200Wp

    Almost viable....

    [1] http://ev-power.com.au/webstore/index.php/12v-lifepo4-batteries/calb-lifepo4-cells/ca60fi.html
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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