SAP and EST - Assumptions

finchy · Nov 8, 2011

Hi,

Suprisingly we have customers calling wanting installations next year....however after looking on the EST the assumptions for exported and savings is 75%/25%. I was under the impression that 50/50 was agreed to use in SAP and EST plus our big six assume 50% exported (arbitary to install export meters). Has this changed ? obviously in my costing model only saving 25% reduces the returns.

I would like to say 100% savings plus 50% export due to not having a export meter, using 3.1p and 14.4p. Its close to the line but if a customer is home all day and the total generation is less than usage then this scenario will occur....

Whats the REAL and MCS guidance on this and has 50% export changed to 75%...?

Many thanks

TedM · Nov 8, 2011

Where on the EST site did you see that? Can you post a link please?

There is talk in DECCs consultation of changing the 50% value for deeming, but nothing else announced AFAIK.

JulianC · Nov 8, 2011

50% deeming applicable to export payments. Separately, EST began recommending using a figure of 25% of total generation for the amount of PV-derived electricity being used in the average household. They believed this was a more realistic figure to use in payback/income calculations.

finchy · Nov 8, 2011

TedM - if you click on assumptions pdf once you have used the EST calculator.

[TD="width: 50%"] Feed-in Tariff - generation rate
[/TD]
[TD="width: 50%"] 43.3 p/kWh until 11 Dec 2011 and 21.0p/kWh after 12 Dec 2011
[/TD]

[TD="width: 50%"] Feed-in Tariff - export rate
[/TD]
[TD="width: 50%"] 3.1 p/kWh until March 2012
[/TD]

[TD="width: 50%"] Electricty price (based on domestic use in 2011)
[/TD]
[TD="width: 50%"] 14.4p
[/TD]

[TD="colspan: 2"] Electricity home use fraction
25% (i.e. 75% of solar electricity is exported to the grid)

[/TD]

finchy · Nov 8, 2011

another point is being MCS we cant give any more emphasis to any other models other than SAP 2009 !! I have just done a sap calc and an equal EST the SAP figures give a higher return than EST. Because EST use 25% !!

xanderfh · Nov 8, 2011

Surely yopu should asses each custmomer as appropriate, if the customer is at home all day then they would potentially be using 100% of the generated electricity. If they want us to start doing epc's we are asses the house's energy rating we should also be looking at the consumers energy usage (time of day, etc)

finchy · Nov 8, 2011

And assume 50% exported tooo ?

xanderfh · Nov 8, 2011

of course, as long as the energy providers dont stipulate export meters fill your boots!!! We need all the angles at the moment to make solar as attractive as possible!!!

GreggElectrical · Nov 8, 2011

I really don't see how anyone can use 100% of the generation. Please explain how this is possible.

xanderfh · Nov 8, 2011

Example: a retired couple at home all day using appliances, etc using all power generated from their panels

GreggElectrical · Nov 8, 2011

So your saying they will always be drawing 4kw minimum? or at least using power equal to the generation at ALL TIMES.

xanderfh · Nov 8, 2011

Assumption of 4kw? A recent install of 2.5kw they had an energy monitor and they were using more or less all they generated (taking into account sap adjustments) obviously each install is different, as we carry out a full energy survey with each assessment we can ascertain their real saving

GreggElectrical · Nov 8, 2011

Please don't think I'm trying to be a clever git. We need to stick together more than ever.

I too have a client with a 2.0kw system installed who is getting close to using all their free electric. They are retired and watch all their meters very closely. They even boil the kettle when sun is out and put it in a thermos in case they want a brew when its cloudy. The kettle only goes on if they generate more than 1kw!!

I also know it is impossible to use 100% of the generated electric unless you have a load greater than you peak generation at all times. Customers can indeed make rather large savings, greater than most calcs. Just be careful estimating 100%.

Have you seen the inverters that link to batteries (small lithium type). They have the capability to Generate, export and charge. They only hold a small amount of power so far but if it can hold 2 Kwh of charge it would make a huge difference to customers bills. Imagine if they can go out on an average day (irradience wise) and come back and put a 13A load into use and it not cost a penny. Even if the PV is only making a few hundred watts.

This could be the next major step in small scale solar IMO.

xanderfh · Nov 9, 2011

Think that's a nedap inverter, incidentally i spoke NICEIC (I know they have a law of their own) the other day and they did say its possible to use 100%, but was advised to use 95% to be safe. We are also looking to Get some printing done for new tariff and asked a few questions to the Niceic and they advised not to yet as they believe more changes are coming (for the good)???

GreggElectrical · Nov 9, 2011

Yeah, that's the one. Spoke to couple of manufactures that say they will be releasing their version in 2012. Have ever had a price on the nedap inverter inc batteries?

Niceic are a joke. I bet the next man you speak to says somthing different. They also would run a mile if anyone ever tried to accuse you of mis-selling.

I hope some changes are coming, i would hold off your printing until.after 12/12.

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 !