I am not sure I understand the deeming process. I am thinking of getting solar thermal for my solid wall detached house. If I get subsidy at what SAP deems my house to require, given basic efficiency measures being in place, then I find that I ought to get paid at 18p x 3742 kWh for the water, and 18p x 26700 or so kWh for the heating, using exemplar figures from the back of the consultation document. That is of order £5500 a year. From my reading of the consultation document, the whole point of the deeming idea is that the subsidy I get is based on the needs of my house rather than the potential yield of my solar thermal system; I can't see anywhere in the consultation document where it says that I have to have installed what my house would need, and so, so far as I can see, given that income derived from actual fuel savings are minimal compared to the subsidy, the scheme encourages me to have the smallest possible system installed, giving payback times of order 1.5-3 years.
Firstly the solar would be unlikely to supply more than 10 -15% of domestic heating requirement and no more than 60% of hot water.
The problem is that when you need it most the solar cannot deliver.
I suspect they will arrive at a deemed figure of about £250 p.a. for domestic hot water and where sufficient panels are installed for home heating this might be about £500, but you'd need a hell of a lot of panels for the latter.
heinbloed
23 Mar 2010, 1:39 PM
The ST heated house is available of the rail. There are many manufacturers/builders offering solar houses running on 100% solar energy. A retrofit can be done as well. I reduced my total thermal energy demand (space heating, cooking, DHW) by 50% this winter just with ST energy. And this winter was much colder then usual. If you can't find a competent architect or (heating-)engineer where you live then shop further abroad. Subsidising energy usage is a waste of energy. Don't get hooked on alms. As soon as the political wind changes (after elections for example) you might have to face reality anyhow.
mbh
27 Mar 2010, 4:42 PM
But Niall, my point is that the document appears to say that the deemed requirement will be based on the SAP assessment of my house, given reaonable efficiency measures being in place. It doesn't say that you have to have enough kit in place to meet the demands of your house, whether for water or for heat. The whole point of "deeming", apart from avoidance of subsidising excess heat generation, is that heat is hard to meter, unlike electricity.
It says that there will be a flat-rate deemed requirement for water of 3742 kWh pa, which at the given proposed tariff of 18p / kWh gives about £700 subsidy for that alone, whatevfer your property.
See if you read the document differently.
NiallMac
28 Mar 2010, 12:28 PM
The document doesn't read clearly.
It is only a consultation paper in any event and these things will be cleared up later, but I did read an ealier paper which suggested solar thermal, for hot water alone, would provide £400 p.a. including typical savings on heat of about £150 p.a.
Two intersting devlopments for next month:
Baxi finally launch Ecogen their Micro CHP on April 6th - but it is expensive when compared to a standard boiler - List price just under £8,000! But this could compare favourably with a PV system for instance.
secondly I hear PVT panels will be MCS approved and qualify for FITs and RHIs! About £15,000 for a 2kWp system installed.
