RE: Automating immersion heater from Solar Voltaic ?

[Peter + Jane <pandj.munnoch@xxxxxxxxxxxxxx>]

Apologies to those that already know, but for=20
those that don't, the Feed in Tariff of 41.3p per=20
kwh applies to every kwh produced whether=20
exported to grid OR used yourself. So FIT is not=20
the point, just that 3p / unit buy in, 6p/ unit=20
E10 or E7 (low rate), 14p/unit E10 or E7 (high=20
rate) xxxp/unit gas or oil I (don't use them so=20
don't have numbers) gives a small incentive=20
(compared with FIT numbers) to use as much as=20
possible rather than export. More continuously=20
running HA and entertainment gear, for example! ;-)

Rgds
Peter

At 12:39 18/01/2011, you wrote:
>
>
>The FIT scheme pays 3p for each KW you export=20
>back to the grid, so not much in it based on=20
>your figures. I guess it depends very much on=20
>the cost of your Gas (and how much we expect Gas prices to rise).
>
>Marcus
>
>From:=20
><mailto:ukha_d%40yahoogroups.com>ukha_d@xxxxxxx=20
>[mailto:ukha_d@xxxxxxx] On Behalf Of Simon
Haslam
>Sent: 17 January 2011 18:15
>To: <mailto:ukha_d%40yahoogroups.com>ukha_d@xxxxxxx
>Subject: Re: [ukha_d] Automating immersion heater from Solar Voltaic ?
>
>It sounds a good idea but I suggest your friend=20
>checks his sums and looks at his hot water usage=20
>carefully before going too far down this route.
>
>For example, a 150l cylinder takes about 7kWh*=20
>to heat from 19C to 60C (that's just a figure I=20
>had to hand) and loses about 1-2kWh (IIRC) a=20
>day. Above that the immersion thermostat will=20
>cut off the supply. So if your friend uses that=20
>much hot water a day in summer then it will=20
>easily absorb 2-3 kWh from his panels. However=20
>with a modern gas boiler say that's 8kWh gas=20
>which on my tariff is 6.7 (first 125 pqtr) or=20
>2.7p/kWh =3D about =A316 a month in the summer which=20
>needs to be compared to what he'd get for=20
>exporting the electricity. (I'm not sure on this=20
>- the FIT distorts things somewhat).
>
>Home PV is a bit like Solar Thermal where you=20
>get the most energy when you least need it. I'm=20
>not certainly not saying using PV for DHW is a=20
>bad idea, just to make sure it's worth the=20
>effort... and if you do the calcs please post=20
>them on here so that others can see your conclusions :)
>
>* kWh energy stored in DHW ~=3D <volume(l)> * 4.18 * <temp
diff> / 3600
>
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>
>


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