[chbot] 60 min of free power per day

Sun Jun 25 11:21:50 BST 2017

Just had a look at the panel & I have 7 16 amp circuits for the underfloor
heating (that I never use) plus the hot water.

I share a 30kva transformer with next door and everything is rated at 100A
as far as I know (the 3 phase power I ran to the shed years ago is on a
100A circuit and looks like the same size cable).

Assuming 7 floors plus water of 3kw each I still can't get to the 100A
(quite!!).

If I could override the ripple control it might be interesting to try ;)

> Mark,
>
> Same problem as solar power in Chch. You get it when you don't need it and
> don't get it when you do. If you could reliably and economically store the
> energy then all may be well, but batteries fail the second test today.
> Under floor heating and cooling with high thermal mass seems to be the way
> to go for solar, and a free hour of power just adds to the fun. Not much
> use unless you build from scratch to cope with it.
> Water heating is typically limited to 3kW or so for a short period, and
> what to do with the rest??
> I did contemplate using a swimming pool as a heat sink/source for heat
> pumps but that also fails the economics test. Free just isn't what it used
> to be . . .
>
> Colin
>
> Get Outlook for Android<https://aka.ms/ghei36>
>
> ________________________________
> From: chchrobotics-bounces at lists.linuxnut.co.nz
> <chchrobotics-bounces at lists.linuxnut.co.nz> on behalf of Henri Shustak
> <henri.shustak at gmail.com>
> Sent: Sunday, June 25, 2017 9:00:07 PM
> To: Christchurch Robotics
> Subject: Re: [chbot] 60 min of free power per day
>
> I love this comment!
>
>> On 25/06/2017, at 8:28 PM, Mark Atherton <markaren1 at xtra.co.nz> wrote:
>>
>> Thank you Helmut,
>>
>> No immediate plans to charge the platoon of Nissan Leafs from the one
>> dangling light socket in the house, for 60mins !
>>
>> Given the obviously available methods of energy storage within a house
>> (hot water cylinder, electric storage heater), and the availability of
>> low cost nighttime electricity, it became quite quickly obvious to me
>> that the whole marketing ploy of electric-kiwi was rather clever. At
>> first brush, it seems a brilliant deal; upon investigation it seems
>> almost useless. Isn't that almost the definition of brilliant marketing
>> ?
>>
>> Regards, Mark
>>
>> On 25/06/2017 8:01 PM, Helmut Walle wrote:
>>> Safety warning...
>>>
>>> A word of caution regarding this line of thought - and I am sure you
>>> are more than aware of this, Mark, but it may warrant stating
>>> explicitly: time is obviously limited. You have one hour to "download"
>>> all the energy you can get, which appears tempting. But there clearly
>>> is an incentive to draw a high current in this tariff.
>>> Now while the service fuse may be rated 60 A, surely many of the
>>> downstream parts of the installation are not. This lies in the nature
>>> of residential wiring work, which is there to provide electricity to
>>> many places in the house, but the power available per socket is quite
>>> limited. The current rating on any individual circuit will typically be
>>> 10-20 A. All circuits should have appropriate over-current protection.
>>> But there are some potential issues with this: any electrical
>>> installation is subject to ageing. One thing that happens is that
>>> connection points of any kind show a higher resistance over time, which
>>> can be due to corrosion or loosening. The increased resistance can lead
>>> to excessive heating under high load (high current). One of the
>>> possible outcomes is a fire. But even moderate heating that doesn't
>>> cause an outright fire can damage and degrade insulation, which can in
>>> the long run again lead to a fire.
>>>
>>> Older houses in particular may be fraught with various issues affecting
>>> the safety of their electrical wiring, which can be a serious safety
>>> risk under very "normal" operating conditions that do not even go
>>> anywhere near maxing out the current ratings.
>>>
>>> So this is something to keep in mind: when connecting higher loads or
>>> drawing higher currents than before from the same installation, be
>>> particularly careful and alert regarding these safety concerns.
>>>
>>> Kind regards,
>>>
>>> Helmut.
>>>
>>> On 25/06/2017 11:50 a.m., Mark Atherton wrote:
>>>> Hello All,
>>>>
>>>> Only just found about this energy company, and their offer of 60 min
>>>> of
>>>> free off-peak electricity per day -
>>>> https://www.electrickiwi.co.nz/hour-of-power
>>>>
>>>> Haven't run-the-numbers yet to see if there are real savings to be
>>>> had,
>>>> but figure this might make an interesting chocolate-fish-challenge for
>>>> the group.
>>>>
>>>> So the question is: how maximize the benefit of this kind of offer.
>>>>
>>>> So for a 60A service to a house, this is almost 14kW, and at $0.35 per
>>>> (daytime) unit, this could amount to just under $5 per day, if the
>>>> entire 60A could be consumed. This amounts to around $150 per month
>>>> possible savings.
>>>>
>>>> Obvious thing to turn on is the heater on the hot tank (3.5kW), which
>>>> would normally be heated at the night rate ($0.15 per unit), so only
>>>> $0.52 savings here.
>>>>
>>>> So, the problem looks like it converges on a need for daytime power,
>>>> if
>>>> the higher saving is to be leveraged.
>>>>
>>>> Anyway, just a daft thought experiment.
>>>>
>>>> Comments welcome.
>>>>
>>>> -Mark
>>>>
>>>>
>>>>
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>>>
>>>
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>>
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>
>
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-- 
Robin Gilks zl3rob/g8ecj
Internet: g8ecj at gilks.org    http://www.gilks.org