Electrical rant .......

This sticky seems to have become unstuck. So here is something that might be stimulating.
I do Electricity bills audits and so I see piles of the things every week. Some findings might not be suitable for readers of a nervous disposition.
Most people think electricity costs about 20c/kW.hr ... how about you?
Some people think night time electricity is miles cheaper
Some people think that pool pumping and lighting are expensive.
A 100W outside light left on for 8 hours a night costs €xxxxx a year?
.......
.......
actually Enel users pay 0.33c - 36c/kW.hr so an immersion heater for example would cost over €1 per hour
Night time electricity also incurs the add on charges and IVA and is only 12% cheaper.
We had a pool pump down to under 200W the other day. Running non stop it saves 62% or around €100 a month.
The LED lamp equivalent to 100W is ......wait for it...........around 8W! Those energy saver halogen things that last 2,000 hrs, come 10 minutes, are not the answer now.
A 100W outside light left on for 8 hours a night costs €100 a year

Love it! Now that's information....      

Wow!  Thank you.

A while back I decided I needed to 'understand' ENEL charges (about the same time I decided I needed to 'understand' quantum physics!).

I gave up on both in a matter of minutes.  Both are impenetrable!  

The pool pump at Casa Ghiro runs 9:00 - 19:00.  Would we be wise to restrict our swimming to the hours of darkness?

Think you need to clarify a few things as to the electricity cost Sagraiasolar. If you have over the 3Kw supply then the costs are scaled according to usage.
The energy use is based on the number of Kwh that you use are on a scale, so it is not a simple calculation.
For the normal supply, you are charged a fairly fixed rate, but then the service charges kick in and these push up the cost.
So the normal rate is between 7-9 cents per Kwh, but then the Servizi Di Rete is added and this is the "devil in the detail", as it applies to any other energy supplier that you switch to, trying to save money.
So here is the detail:
Up to 1800 Kwh P.A 9 cents per Kwh
1800 - 2640 11 cents Kwh
2640-4440 15 cents Kwh
4440+ 19 cents Kwh.
Of course all these prices have IVA added on, as always!!

If you include the basic service charges, divided by the number of Kwh used, then you may get to the 33C per Kwh.
I use between 9000-10000 Kwh here per year, as all electric apart from a gas hob.
Do not know how you have calculated, but would be interested to see.

my head hurts....

Fight, fight!

I have done an analysis of the ENEL charges based on what ENEL publish on their website for the period 1 July to 30 Sept and they work out as follows (including IVA). Not the easiest pricing sheule to work from

ENEL	Monthly useage					< 3kw supply			>3kw supply
For over 3kw supply or for over 2,700KWH per annum						Day	Night/Weekend		Day	Night/Weekend
Excluding fixed/monthly charges but incl IVA
						Euro	Euro		Euro	Euro
First	150		KWh			0.150392	0.142736		0.210408	0.202752
Next	66.67		KWh			0.211607	0.203951		0.22902	0.221364
Next	150		KWh			0.282029	0.274373		0.272272	0.264616
Excess						0.333465	0.325809		0.318615	0.310959

As you can see evenings and weekends is cheaper but not by a lot

Ah Panner- your big mistake was this: --- based on what ENEL publish on their website  .....  

1/. Re the pool pump.  I think there are two functions that could be profitably split... first you need to move all the water through the filter and some of that could be done at night  then you need to sweep off the bugs so some day time running is needed too. The easy way to do this is to get  pump timer that can do several on/offs a day.  Better still is to fit a modern pool pump and turn it down to about 200W and run it 24/7 ... for cleaning duties you can turn it right up again.

2/. My figures are dead right believe me... the price is the headline result of every report I do.  For a quick check take your last bill and divide the money by the power bought.
The fixed costs are fairly trivial so the cost of buying one more kW (the marginal cost) is only a tiny bit lower.

3/. The quoted figures in the various bands are a bit missleading if you think that's all you are paying ... they are just one of the four ways you are charged and then + IVA

Hi Sagraiasolar.
Using your calculations, then I agree that you can get to the 33 cents, but if take off the supply standing charges, which are always going to be there, however much electricity you use, then the KWh  cost is lower.
In the case of here, then my fixed costs work out @ E 50 per 2 months inclusive of IVA. Removing those from the formula, left the actual energy use of 860kwh @ 27c inc IVA as the average consumption price figure.
Anyone who does not hit the 4th level price price band, would find that average lower of course, as long as you remove the fixed charges.

When looking at overall cost the average price per KWh is fine and easy to calculate from the bill (with/without the fixed charges).

However when looking at costs/savings from changes to either behavior or equipment it is the marginal cost per KWh that is important - and that depends on which pricing level you fall into, time of day and and how much is left at that level. Once into the 4th level then it is all at the highest marginal price.

Using an average of the 4th level gives a marginal price of around 31 to 32c  per KWh (incl IVA)

Panner wrote:Once into the 4th level then it is all at the highest marginal price.Using an average of the 4th level gives a marginal price of around 31 to 32c  per KWh (incl IVA)

Hitting Scaglione 4 is rare for me but from my April bill the marginal cost of a daytime energy rise was 0.1862 (scag 4) for the quota variabile + 0.08983 for an F1 day time kW.hr.  Add 0.01256 for dispacciamento, 0.00024 for perequazione
A total of €0.28883 and €31.77 with 10% IVA.  I expect my bills are quite low (€208.07 for this one) and almost everyone will enjoy a marginal rate like this for day time consumption as outlined by Panner above.
Badger - your rate sounds excellent - is this the heat pump special rate at work?  I once got to grips with this but I'm out of date now... do you have a level in mind where it pays to transfer over?

Badger - your rate sounds excellent - is this the heat pump special rate at work?  I once got to grips with this but I'm out of date now... do you have a level in mind where it pays to transfer over?

Hi again.
No, I am not on the BTA3 tariff, as although I meant to go for it this year, I still had some work to do burying the tubing for the supply from the pylon, so hopefully next year in the summer!!!
I am waiting for one of my clients to let me know their costs for running a BTA3 supply on a 17Kw output GSHP, as this is the first full year on that meter for them, so we can see the difference from the one supply and then compare to the 2 meter supply ( House + Pump ). Will post more details when I hear further. The cost per Kw supply is quite high, but the rate is about 50% lower for the usage.
I think in the example that I posted below, that they have messed up on the BTA2 tarrif, but the 3 looks about right.

http://www.enel.it/it-IT/reti/enel_distribuzione/venditori_tariffe/usi_diversi/bta1-bta5.aspx
http://www.enel.it/it-IT/reti/enel_distribuzione/venditori_tariffe/esempi/
The heat pump here, just on water heating, is only operating about 3-4 hours per week ( in the summer months ), @2.1 kwh, so it is minimal cost, only taking about 5 odd mins to boost from 46C to 53C, on a 160 ltr tank.
How many Kw have you as a supply, as my bill for the June - July period, did not seem too bad @ E280.

Geotherm

Do you know if the special rate/seperate meter applies to ASHPs as well.

I am currently looking at one for my heating.

Thanks

Panner wrote:GeothermDo you know if the special rate/seperate meter applies to ASHPs as well.I am currently looking at one for my heating.Thanks

Yes Panner, it applies to GSHP, ASHP and air/air, with inverter technology. You must quote it is a heatpump when you apply, as one of our clients electricians messed the application up and they were charged the 21% IVA. Resolved now though with a refund of the overcharge!!!

Edit: With just a holiday home, you need to look at it carefully, as the extra fixed costs may overide the saving, unless you are there for a reasonable time in the winter months!!

Thanks Geotherm

Whilst it is a holiday home at the moment we are planning on moving over and being there most of the time from around Easter time next year. I am currently weighing up the options and costs/savings in terms of fuel costs/capital expenditure and payback periods so that all the work is done for then.

Geotherm wrote:
How many Kw have you as a supply, as my bill for the June - July period, did not seem too bad @ E280.

I agree - a remarkably nice bill especially considering you are majoring on electricity and paying extra for a fat supply. I can only compare with this by cheating - my 4.6kW PV solar panels help a lot.  My ENEL supply is 6kW.
As your heat pump consumption is not disimilar to that of an electric kettle I wonder if you actually need to have a particularly fat supply?

Sagraiasolar wrote:

Geotherm wrote:How many Kw have you as a supply, as my bill for the June - July period, did not seem too bad @ E280.

I agree - a remarkably nice bill especially considering you are majoring on electricity and paying extra for a fat supply. I can only compare with this by cheating - my 4.6kW PV solar panels help a lot.  My ENEL supply is 6kW.As your heat pump consumption is not disimilar to that of an electric kettle I wonder if you actually need to have a particularly fat supply?

 The supply was based on the appliances that we brought over, as we did not want it to trip out if we used too much. To use a washing machine, 3Kw electric oven, 3 kw kettle, all at the same time would tend to cause problems. Therefore, in a cost analysis, it was better just to pay for the extra kw's supply charge, as it does not effect the per unit rate. Our view only!!!
I must admit, that neither of us here like solar panels, so they were discounted in the early stages, as apart from the costs and the rebates at the time, we did not think them suitable on a 250 year old building.

If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.
I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc.
 I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

I must admit I've read your posts on these heat pumps many a time and never looked to see what they are! Reading up they do seem "magical", so I wonder why more people don't have them, although seeing them I see what I thought were just air con units on houses could well be the same thing... On that subject two things come to mind; they look ugly outside houses and how much installation effort and cost is there?

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

I haven't got a bill, but looking at the ENEL site their other figures bear a close resemblance to bills I have for my ordinary tarriff (D3).

The rates on the BTA3 tariff also seems to change every month for part of it (vendita) whilst the other part (rete) is fixed for the quarter

Based on their quoted rates for September the unit cost (including IVA) is:

F1 (Weekday 8am to 7pm)      19.151 Cents/KWh

F2  (Weekday 7am to 8am and 7pm to 11pm and Sat 7am to 11pm)    18.8309 Cents/KWh

F3 (rest of the time)    17.3349 Cents/KWh

Fixed Charges (incl IVA)

6KW supply E39.43

3KW supply E30.23

Taking a weighted average (assuming constant consumption level) gives a price 0f 18.2946 Cents/KWh. Based on the marginal costs arrived at in my earlier post the saving works out at approximately 13 Cents/KWh

On a 6KWh supply this would require a monthly consumption of 302 KWh to "break even" ignoring any installation costs for wiring/meter etc. (for a 3KW supply the break even is 232 KWh per month). In both cases assuming that the other consumption means that there is some charge in each of the months where the heat pump is operating at the highest rate. If not then the savings would not be as much and the break even would be higher

Sagraiasolar - I would be interested in looking at your spreadsheet when you put it together. May even have a go at doing one myself but I assume you already have a basic model that you can adapt.

Would also be interested in the interaction between solar PV offset and how the own use is netted off - is it first against the general useage (D3 Tariff) and then the heat pump (BTA3 Tariff) as I am looking at solar PV as well as an ASHP and it may affect the savings/amount of solar PV (and therefore initial cost/payback)

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

Thought I had emailed you a BTA3 excel beta. a few years ago. If you need it again just let me know.

stevegwmonkseaton wrote:

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

I must admit I've read your posts on these heat pumps many a time and never looked to see what they are! Reading up they do seem "magical", so I wonder why more people don't have them, although seeing them I see what I thought were just air con units on houses could well be the same thing... On that subject two things come to mind; they look ugly outside houses and how much installation effort and cost is there?

Steve.

Probably what you have seen on the outside of houses, is either a normal aircon unit or a air/air one. A ASHP, is normally sited on the ground, and are not so obvious.

http://www.geotherm.it/Pompe-di-calore-aria-acqua-e-aria-aria.html

A GSHP is completely hidden, as it either sits in the house, or in a outbuilding.

http://www.geotherm.it/Pompe-di-calore-geotermiche-riscaldamento-alta-temperatura.html

As regards to installation, then it all depends on which system you go for in the beginning, or as a retrofit. ASHP a couple of days to connect up. GSHP, 2-3 days  for the trenches and laying the ground probes, with a couple of days for the pump connection.
Cost will vary on pump size and type, DHW tank size according to the house size and insulation levels.

Hope this answer is as near as possible to your question.

Panner wrote:

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

I haven't got a bill, but looking at the ENEL site their other figures bear a close resemblance to bills I have for my ordinary tarriff (D3).

The rates on the BTA3 tariff also seems to change every month for part of it (vendita) whilst the other part (rete) is fixed for the quarter

Based on their quoted rates for September the unit cost (including IVA) is:

F1 (Weekday 8am to 7pm)      19.151 Cents/KWh

F2  (Weekday 7am to 8am and 7pm to 11pm and Sat 7am to 11pm)    18.8309 Cents/KWh

F3 (rest of the time)    17.3349 Cents/KWh

Fixed Charges (incl IVA)

6KW supply E39.43

3KW supply E30.23

Taking a weighted average (assuming constant consumption level) gives a price 0f 18.2946 Cents/KWh. Based on the marginal costs arrived at in my earlier post the saving works out at approximately 13 Cents/KWh

On a 6KWh supply this would require a monthly consumption of 302 KWh to "break even" ignoring any installation costs for wiring/meter etc. (for a 3KW supply the break even is 232 KWh per month). In both cases assuming that the other consumption means that there is some charge in each of the months where the heat pump is operating at the highest rate. If not then the savings would not be as much and the break even would be higher

Sagraiasolar - I would be interested in looking at your spreadsheet when you put it together. May even have a go at doing one myself but I assume you already have a basic model that you can adapt.

Would also be interested in the interaction between solar PV offset and how the own use is netted off - is it first against the general useage (D3 Tariff) and then the heat pump (BTA3 Tariff) as I am looking at solar PV as well as an ASHP and it may affect the savings/amount of solar PV (and therefore initial cost/payback)

Hi Panner.

Some figures that you may like to work on

This is for the heat pump installed here, but I have only detailed operating hours over the 2012-2013 year and 2013 to date. If you need a more detailed info, for example week by week, with outside air temp recorded, or month by month, then let me know.
Have just checked prior to typing this, and since Monday a.m to 14.00 hrs today, it has operated for only 3 hrs. Heat distribution from its display over the year, averages out @20% DHW and 80% heating..
The pump here, GSHP 11Kw, draws 2.2Kwh @ 35C output temp @ 0C external, (underfloor heating as here), or 3.0Kwh @ 50c and 0C external, which is radiator operating temperature.

Anyway the figures: 02/01/2012 - 30/12/2012 = 1782 hrs x 2.2 kwh = 3920.4kwh.
                            30/12/2012 - 23/09/2013 = 1354 hrs x 2.2 kwh = 2978.8kwh.

What always must be taken into account is that these units are meant to operate 24/7, therefore in the winter months they hit the F1 rate during the day. My average F1 use is around 37%, for the whole house.

Geotherm wrote:

stevegwmonkseaton wrote:

Sagraiasolar wrote:If anyone can send me a copy of a recent BTA3 heat pump bill I'll gladly build an Excel model to compare rates and determine which level is worth changing over.. I'll then share it with you all.I find the ENEL site too weird to trust so the only way is to see a real bill with real money etc. I'm quite enthusiastic about this because, as I expect you all know by now, a heat pump is already a very cheap energy provider - magically multiplying energy bought by about 3 times.

I must admit I've read your posts on these heat pumps many a time and never looked to see what they are! Reading up they do seem "magical", so I wonder why more people don't have them, although seeing them I see what I thought were just air con units on houses could well be the same thing... On that subject two things come to mind; they look ugly outside houses and how much installation effort and cost is there?

Steve.Probably what you have seen on the outside of houses, is either a normal aircon unit or a air/air one. A ASHP, is normally sited on the ground, and are not so obvious.

http://www.geotherm.it/Pompe-di-calore-aria-acqua-e-aria-aria.html

A GSHP is completely hidden, as it either sits in the house, or in a outbuilding.

http://www.geotherm.it/Pompe-di-calore-geotermiche-riscaldamento-alta-temperatura.html

As regards to installation, then it all depends on which system you go for in the beginning, or as a retrofit. ASHP a couple of days to connect up. GSHP, 2-3 days  for the trenches and laying the ground probes, with a couple of days for the pump connection.
Cost will vary on pump size and type, DHW tank size according to the house size and insulation levels.

Hope this answer is as near as possible to your question.

GSHP I have looked into (still know nothing much about them), it was the ASHP that I'd  not really bothered with. I get the impression with these installation could be a lot easier and cheaper (even if they are not quite as good). It was THESE things I saw that made me think they looked like aircon units...