When exactly should I be Boiling a Kettle when I have a Solar Panel?

[Deactivated] on 30/11/2018 - 13:44
Last edited 30/11/2018 - 14:02

I was reading something dubious about net metering and smart meters. Apparently the energy imported/exported is calculated instantaneously and then logged every 30 mins. That means I should only be boiling the kettle when the sun is actually shining rather than if it was shining for 8 mins beforehand on say a 1kwh system and then boiling on a 2200W kettle.

In fact you can be importing 1000w whilst also exporting at 12c just a few mins later, assuming you only have 1kw of panels. I looked online at EnergyAustralia and they say they have 30 minute interval data, but when I login, I can only see data for hourly… I'm thinking of looking at my old data but from what I can see I don't see any spikes during certain hours where I know I have boiled water. It is zero, which makes me think the instantaneous logging method is incorrect.

I've also logged some data for today and will wait for the data to become available. I basically am always at home at 1pm when the sun is shining and boiling a kettle, and on basically everyday I have zero when it was sunny, where I know I boil the kettle in that hour. Even on cloudy days I am at zero. 2pm is when the peak time hits for me.

https://forums.whirlpool.net.au/archive/2461833

Should I be trying to get 700W 240V kettle instead. I'm thinking of using a 700W portable hotplate instead and seeing how that works.

Can someone confirm what is the actual method and whether the user philius on whirlpool is correct or not?

I was also thinking of adding another 1kw of panels if this is the case, just enough for the kettle when the sun is at 100% brightness. (Will need to do a cost benefit analysis)

Context

I probably wasted 4c of electricity typing this and thinking about this for over an hour, 100w on computer.

But yeah, I'm retired so I just look at random things now. Think about the theory of how things actually work.

Maybe I'll find something better to spend my time on in the future.

Electrical & Electronics

Comments

  • spackbace on 30/11/2018 - 13:45
    +8

    Wow…

    You're really that concerned about when you should have your cuppa?

    I was also thinking of adding another 1kw of panels if this is the case, just enough for the kettle when the sun is at 100% brightness

    Nice troll.

    • [Deactivated] on 30/11/2018 - 13:48

      No, lol not really. It's like 4c.

      Yeah, I thought it was interesting.

      There are plenty of people trying to optimise the amount of use during sunlight so nothing gets exported.

      • spackbace on 30/11/2018 - 13:49
        +3

        If you're concerned about 4c of energy, while using a device to type this post, using either a battery (which will need charging), or electricity, then I'm truly concerned where your priorities lie.

        • [Deactivated] on 30/11/2018 - 13:50
          -1

          Realistically isn't the minimum one should get 2kw panels anyway because of peak appliances, usually space heaters are like 2000W too.

          Yeah, been thinking of battery too. (Not cost effective though at the moment)…

  • Nugs on 30/11/2018 - 13:50

    1kW solar?
    .

    • [Deactivated] on 30/11/2018 - 13:51

      I think I need more. lol.

      This is the old panels from the free offer btw…

  • altomic on 30/11/2018 - 14:04
    +12

    amateur - pre-heat the water by placing it in black jar inside a much larger transparent sealed container which is in direct sunlight.

  • EightImmortals on 30/11/2018 - 14:06
    +7

    Mate, if making a cuppa is getting to be as complicated as flying the Starship Enterprise then we've taken a wrong turn somewhere.

    • spackbace on 30/11/2018 - 14:13
      +1

      See post edit.

      OP is retired and needs a hobby 😂

  • macca9123 on 30/11/2018 - 14:14
    +11

    Is there a nearby park with a free electric bbq that you could use to boil water in a pot instead?

  • [Deactivated] on 30/11/2018 - 14:15
    +5

    When the sun is at it's highest and the moon can be seen in the east.

    When the tide is at it's lowest and the wind is against your back.

  • mick123 on 30/11/2018 - 14:34
    +6

    Instead of boiling it everytime you want a cuppa, to save time and electricity, boil 2-3 litres at a time. Use what you need for your coffee/tea and put the rest in a heatproof bottle in freezer. When you need more water, bring water to a boil in saucepan to defrost the bottle and once defrosted, pour required amount of this water into cup/mug and microwave for 90 secs.
    So you only need to use your kettle once a day or so

  • poboy on 30/11/2018 - 14:49
    +3

    In the spirit of getting actual data, I filled up my kettle to exactly 2 cups of water. I then put a smart plug on the powerpoint. The cost of heating this water was so little, it didn't even register to three decimal places ($0.000), so alas I can't report back the actual electricity cost.

    • macca9123 on 30/11/2018 - 16:04
      +1

      Back of the envelope calculation:

      The energy required to heat two cups of water (500ml) from say 15 degrees to 100 degrees is:
      500g * (100-15 degrees) * 4.186 = 177,905 joules

      (where 4.186 is the specific heat of water in joules per gram-degree).

      One joule is one watt-second, so expressed in kilowatt-hours this is 177,905 / (3600 * 1000) = 0.049418 kWh

      With electricity roughly costing 25c/kWh this means that boiling two cups of water in the kettle costs 0.25 * 0.049418 = 1.2 cents

      Of course, just because a device displays 3 decimal places doesn't mean that it is accurate to 3 decimal places too.

      • poboy on 30/11/2018 - 19:43

        Nice, thanks

  • [Deactivated] on 30/11/2018 - 16:49

    You're 1kw system will not be producing 1kw most of the time. There is a lot of factors like angle, orientation, ambient temp, etc. You can model all these through various online simulators.

  • John Kimble on 30/11/2018 - 17:11

    I probably wasted 4c of electricity typing this and thinking about this for over an hour, 100w on computer.

    But yeah, I'm retired so I just look at random things now. Think about the theory of how things actually work.

    Maybe I'll find something better to spend my time on in the future.

    Bahahaha

  • hawkeye on 01/12/2018 - 00:01

    I have 17 x $1.50 magnifying glasses from the $2 shop to make a mug of hot water for coffee and on rainy days I like to drink lukewarm aquapure natural straight from the mug.

  • MikeKulls on 01/12/2018 - 22:34

    A better question is when should you put on the washing machine or dishwasher. Answer is while the sun is brightest, unless you still have the 66c feed in tariff. Then you should do it at night.

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