SAP and EST - Assumptions

Solluva · Nov 9, 2011

Now if we all had meters that run backwards we wouldn’t need a complicated and expensive battery system. By not having a meter that runs both ways encourages one to attempt to use and in many cases waste all the electricity being generated. The best virtual battery would be the grid.

If one of the intended spin offs of micro-generation is an all round reduction in electricity use then a reversible meter is the answer. I agree with GreggElectrical it is impossible to use 100% of what you generate. Of the 480kWh generated from our seven week old installation only about 16% has been exported and that’s with being home all day long, taking great care in our use and having a meter that goes backwards to the nearest ten units.

Give us all reversible meters and stop the actual power fed into the grid payments.

SRE · Nov 9, 2011

There is no way, other than having heating appliances working during the summer to use up the generated heat that you will use 100% of what a 4kwp generates and I'd go as far as to say it's highly unlikely that you'd do that on a smaller system either. With a 1 - 1.5kwp it's potentially possible but anything more than that it's almost impossible.

I work from home, have a 4kwp system and in the Summer on a good day we'll generate 28kwh and use about 6 - 7. Washing done dishes washed, diner cooked etc etc still got 21kwh going back into the grid - how do you get that to 100% use of electricity generated????

finchy · Nov 9, 2011

I think we've gone off from my orginal question, However its interesting to see your comments. Particulary the actual usage %, is it worth recommending getting an export meter installed if customers use less than 50%....
or would it be like having a water meter installed, good idea until you start using more !!!

Anyhow my question was the difference in EST and SAP for export/savings, for customer illustration post 12th Dec. I guess its subjective depending on use, up to now I have used 50%. But the EST assume 25% exported....

SRE · Nov 9, 2011

EST are assuming 75% exported not 25%. Have a look at your post, it says EST assume 25% home use (which is based on a study of the actual use of 70 different houses) what I don't know is whether the figures assume that an export meter has been fitted and therefore there is 75% generation tariff or of they have assumed the deemed 50%.

finchy · Nov 9, 2011

Sorry that right. Its all very difficult to try get some sort of strategy/pricing post 12th, using 75% makes the ROI even worse...where did DECC get there figures from !