So now I have a solar PV system how do I make the most of it???

Cardew

thenudeone wrote: »

Anyway - unless you have a smart meter fitted it doesn't make any difference how much of solar electricity you actually use. The tariff just assumes 50%.

Of course it makes a difference!

If I generate 2,000kWh pa, apart from FIT I get 1000 x 3p(£30) for exported electricity.

I get that £30 regardless of exporting all 2000kWh or nothing.

Every kWh I use in my property saves me, say, 10p. So if I manage to use 500kWh I save £50 off my bill, for 1000kWh I save £100 etc etc.

So every extra 10kWh I manage to use in the house saves me £1 off my electricity bill.

The whole point of this thread is to find ways of using more of the generated electricity in the house!!!

P.S.
Yes at the current price of oil it costs about twice that of mains gas.

John_Pierpoint

.........as long as I don't use it for heating water, if I have gas or a night time electricity tariff as the alternative way of heating water.
If I do have these alternatives then I am only saving half as much.

John_Pierpoint

Mcfi5dhc wrote: »

Rank Postcode Area Count Percent Postcode Town/City
1 S 1238 6.28% Sheffield (guess who!)
2 PO 659 3.34% Portsmouth
3 EX 550 2.79% Exeter
4 BS 489 2.48% Bristol
5 AL 482 2.44% St Albans
6 RG 389 1.97% Reading
7= DN 385 1.95% Doncaster
7= NG 385 1.95% Nottingham
9 TN 373 1.89% Tonbridge
10 NR 352 1.78% Norwich

Data above is straight from the data - I have not tried to combine the London postcodes into one clump, but I guess they would be quite high in the rankings if I did.

HTH

Darren

PS sorry about the formatting, I did try and tidy it up a bit

Very interesting - we would need to know the number of households per post code to know something really significant BUT I wonder why Sheffield seems to be a hot bed of PV electricity?

With the exception of Bristol, I don't think this list matches the "greenie" tendencies of the local people.
Has anyone got an idea of the balance between "rent a roof" and "invest your own money" ?

Cardew

John_Pierpoint wrote: »

Very interesting - we would need to know the number of households per post code to know something really significant BUT I wonder why Sheffield seems to be a hot bed of PV electricity?

" ?

A Shade Greener(ASG) were the first large company to get into the 'rent a roof' business and initially all their systems were installed only in the South Yorkshire area; they have installed thousands of systems

They are based in Sheffield.

thenudeone

Cardew wrote: »

Of course it makes a difference!

If I generate 2,000kWh pa, apart from FIT I get 1000 x 3p(£30) for exported electricity.

I get that £30 regardless of exporting all 2000kWh or nothing.

Every kWh I use in my property saves me, say, 10p. So if I manage to use 500kWh I save £50 off my bill, for 1000kWh I save £100 etc etc.

So every extra 10kWh I manage to use in the house saves me £1 off my electricity bill.

Is it not the case that in the absence of a smart meter, the readings on your generation meter and standard utility meter will be exactly the same regardless of when you used or generated any particular unit?
A standard meter does not measure the amount exported separately from what is purchased; there is just one single measurement.
In your example, you will "save" the balance of: 2000 (generated) LESS 1000 (assumed exported) = 1000 units

Cardew wrote: »

The whole point of this thread is to find ways of using more of the generated electricity in the house!!!

Which is perfectly valid if
1) you want to maximise the use of solar power by yourself personally and therefore minimise the draw from the grid which may come from fossil fuels OR
2) you have a smart meter in which case it's clearly financially beneficial

I have based my reasoning on The Government’s Standard Assessment Procedure for Energy Rating of Dwellings SAP 2009 available here: http://www.bre.co.uk/sap2009/page.jsp?id=1642

Which states on page number 79 (not pdf page 79):

The cost saving associated with the generated electricity depends on whether it is used directly within the dwelling or whether it is exported. Electricity used directly within the dwelling is valued at the unit cost for purchased electricity (standard tariff, or the high/low rate proportions given in Table 12a in the case of an off-peak tariff). Electricity exported is valued at the price for electricity sold to the grid. The effective price depends on a factor b, which is in the range 0.0 to 1.0 and is defined as the proportion of the generated electricity that is used directly within the dwelling. The value of b depends on the coincidence of electricity generation and electricity demand within the dwelling. At present the value of b = 0.50 should be used for SAP calculations: this will be reviewed in future if relevant data becomes available.
The fuel price used for calculation of the cost benefit is:
b ´ normal electricity price + (1 - b) ´ exported electricity price.
where the normal electricity price is standard tariff, or weighted high and low rates (Table 12a) if an off-peak tariff.

I don't yet have a system installed but I understand that 0.5 is used for the calculations where no smart meter exists; so it doesn't matter.
Unless I have missed something!

zeupater

thenudeone wrote: »

Is it not the case that in the absence of a smart meter, the readings on your generation meter and standard utility meter will be exactly the same regardless of when you used or generated any particular unit?
A standard meter does not measure the amount exported separately from what is purchased; there is just one single measurement.
In your example, you will "save" the balance of: 2000 (generated) LESS 1000 (assumed exported) = 1000 units


Which is perfectly valid if
1) you want to maximise the use of solar power by yourself personally and therefore minimise the draw from the grid which may come from fossil fuels OR
2) you have a smart meter in which case it's clearly financially beneficial

I have based my reasoning on The Government’s Standard Assessment Procedure for Energy Rating of Dwellings SAP 2009 available here: http://www.bre.co.uk/sap2009/page.jsp?id=1642

Which states on page number 79 (not pdf page 79):

The cost saving associated with the generated electricity depends on whether it is used directly within the dwelling or whether it is exported. Electricity used directly within the dwelling is valued at the unit cost for purchased electricity (standard tariff, or the high/low rate proportions given in Table 12a in the case of an off-peak tariff). Electricity exported is valued at the price for electricity sold to the grid. The effective price depends on a factor b, which is in the range 0.0 to 1.0 and is defined as the proportion of the generated electricity that is used directly within the dwelling. The value of b depends on the coincidence of electricity generation and electricity demand within the dwelling. At present the value of b = 0.50 should be used for SAP calculations: this will be reviewed in future if relevant data becomes available.
The fuel price used for calculation of the cost benefit is:
b ´ normal electricity price + (1 - b) ´ exported electricity price.
where the normal electricity price is standard tariff, or weighted high and low rates (Table 12a) if an off-peak tariff.

I don't yet have a system installed but I understand that 0.5 is used for the calculations where no smart meter exists; so it doesn't matter.
Unless I have missed something!

Hi

I think that the issue revolves around the assumed 50%. if you look at how the FiT system came about you'll find that the assumed 50% export came from analysis of small systems ~2kWp. As the system rated generating capacity increases it becomes harder to consume 50% in the home, therefore you'll find that far more than 50% will be exported on something like a 4kWp system.

The majority of people who invest what is effectively the value of a new car on glazing their roof attempt to recoup their fixed investment as quickly as possible and the only way this can be achieved/influenced is through changing personal energy usage profiles. It actually become quite fun/obsessive for a while as people play with their new toy to maximise the return, then it just becomes habit.

Every unit of self generated energy which is consumed efficiently in the home through changing the usage profile reduces the import requirement & therefore the cost to the household. The problem with the SAP calculation referenced is that the 50% assumed export is a one size fits all (no pun intended ) figure, where a sliding scale would have been more appropriate. I personally don't like the fact that the assumed export figure is also used as an assumed self-usage which is misleadingly used to calculate the payback on your quotation. Take an extreme example where a household uses ~3000kWh/year and has a system capable of generating ~3000kWh/year, the saving value would be calculated on ~1500kWh/year, but if you have a system which produces ~9000kWh/year the saving would be calculated on 4500kWh, which is far more than the household would use in daylight & darkness combined .....

HTH
Z

grahamc2003

thenudeone wrote: »

I don't yet have a system installed but I understand that 0.5 is used for the calculations where no smart meter exists; so it doesn't matter.
Unless I have missed something!

Yes, you are missing something.

You are confusing the method of calculating the predicted financial projections you will be quoted, with what happens in real life.

If you have no export meter, projections will be made on the basis you quoted (i.e. 50% of the predicted output being exported and worth 3p (or ish) per kwh, and half being assumed to be used in your home and valued at whatever your tier 2 day rate electricity price is.

The reality is that you will be paid 3p for 50% deemed exported, and you'll get the option to use 100% of the electricity generated, which will be worth more or less than the calculations.

For various reasons as discussed on here, it looks like in reality, it's both unlikely you will use 50% generated, and that the average value of that used will be less than your tier 2 day rate, so the value will be less than the projections. Although you'll probably export more than 50%, you deemed export will stay at 50%, and you'll be paid on that basis.

It all boils down to, as should be obvious from this whole thread, that you want to use as much of the generated power as possible, and use it in a way which maximises its value (i.e. not for heating or hot water which, for the vast majority of people, lowers the value).

Cardew

I don't know what you mean by a 'standard utility meter'.

The cost saving associated with the generated electricity depends on whether it is used directly within the dwelling or whether it is exported

That quote from SAP 2009 is exactly what I was saying.

That seems to be at odds with this statement of yours:

Anyway - unless you have a smart meter fitted it doesn't make any difference how much of solar electricity you actually use. The tariff just assumes 50%.

e.g. Your system and my system both generate 2,000kWh pa. You use 1,000kWh of that generated power in the house and I use 500kWh. (Assume electricty for the house costs 10p/kWh)

You get 2,000 x 41.3p, + 1,000 x 3p + save 1000 x10p = £956

I get 2,000 x 41.3p, + 1,000 x 3p + save 500 x10p = £906

So the more you use in the house the greater the saving. Even after smart metering is introduced that statement still applies as it is better to use a kWh that saves you 10p rather thanexport it and get 3p.

The title of this thread is "So now I have a solar PV system how do I make the most of it???" i.e. find ways of using more electricity in the house.

If you are saying that you get paid @ 3p/kWh for 50% of the generated electricity regardless of how much is exported, then that is correct, but in the context of this thread, and in your response to the post of Graham's you quoted, it does make a difference 'how much you use'!

Cardew

Just had a thought(rare occurance)! Could your reference to 'Standard Utility meter' mean you think the 2,000kWh generated will 'turn back' the mains electricity meter by 2,000kWh?

If so that happens on a very few meters, and is of course illegal!

Equaliser123

Just a reminder to those with panels - as I've not heard from my FIT provider (EON) as to what it is going to do about the FIT price increase, I will be sending in a reading of my generation meter tonight as the FIT increases tomorrow.

Nice to think of my solar panels having a pay rise....