[OpenTRV-interest] Fwd: Storage heating, dynamic demand, and OpenTRV

[Damon Hart-Davis]

Begin forwarded message:

> From: Damon Hart-Davis <EMAIL ADDRESS HIDDEN>
> Subject: Re: [OpenTRV-interest] Storage heating, dynamic demand, and OpenTRV
> Date: 7 September 2014 18:17:38 BST
> To: "Open, non-developer list for interested parties" <EMAIL ADDRESS HIDDEN>
> Cc: Damon Hart-Davis <EMAIL ADDRESS HIDDEN>
> 
> Hi,
> 
> My DHW is all ‘instant’ otherwise yes, that could be a better option for me for example.
> 
> Just trying to find some cheap low-hanging fruit for some of the 500,000 people in the UK with PV but without a hot water tank.
> 
> Also, trying to be nice to the grid, by smoothing flows, with different sorts of storage.
> 
> Rgds
> 
> Damon
> 
> 
> On 7 Sep 2014, at 12:47, Mark Wigmore <EMAIL ADDRESS HIDDEN> wrote:
> 
>> Hi Damon,
>> 
>> I had storage heaters until a year ago when I switched to gas central heating. I had some fairly modern storage heaters and their design is such that there is a constant air flow through the core. There are dampers to increase the flow ('boost') but I don't know of any design that will stay hot for more than a couple of days. Having said that, I can see that they could be used in conjunction with PV as a kind of reverse Economy 7, heating up during the day when there's surplus generation to provide warmth in the early evening. As you say, +/- one or two months around the winter solstice there might be little benefit, but in spring and autumn there could be something. The alternative is to dump the energy into the hot water system via an immersion heater, as that's used all year round, but if you're going to do that it might be better to use solar-thermal panels instead.
>> 
>> One thing I have noticed since removing the storage heaters is that in the summer there is a much wider variation in room temperature. I think they were actually stabilising the temperature by acting as a sink in the day and a heater at night. I kept the boost dampers open from spring to autumn to enhance the airflow for this effect.
>> 
>> Hope this is of interest,
>> 
>> Mark
>> 
>> PS I still have the storage heaters if you want to experiment.
>> 
>> PPS Another thought that's just occurred to me is to use the excess PV to run a reversible heat pump, maybe using storage heater bricks on one side of the pump?
>> 
>> 
>> On 7 September 2014 12:28, Damon Hart-Davis <EMAIL ADDRESS HIDDEN> wrote:
>> Hi,
>> 
>> This isn’t particularly about money (or indeed carbon yet), though given the ratio of export to retail tariffs it might pay off.  And the generation component is paid just the same.  And many people’s export is ‘deemed’ anyway.
>> 
>> This is about attempting to minimise grid flows to/from a house which has some virtues of its own, and looks trickier than I had expected given how fast power generation from PV varies from my own measurements.
>> 
>> Note that in our case because of our E- and W- facing PV we generate relatively little power in winter, but still probably only get to consume about 50% of it in house because of timing, and a resistive heating dump is probably the most robust thing to practice on!
>> 
>> Rgds
>> 
>> Damon
>> 
>> 
>> On 7 Sep 2014, at 12:21, John Stumbles <EMAIL ADDRESS HIDDEN> wrote:
>> 
>>> On 07/09/14 12:00, Damon Hart-Davis wrote:
>>>> Hi,
>>>> 
>>>> I have a thought in the back of my mind about carefully making some
>>>> use of residual exported solar PV generation in winter with
>>>> highly-efficient storage heaters controllable by an extension of
>>>> OpenTRV to supplement a gas-fired system.
>>> 
>>> Wouldn't you get more money selling PV 'leccy back to the grid than it would be worth to you as heat?
>>> 
>>> 
>>> --
>>> John Stumbles                                    http://stumbles.org.uk
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>>> 
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