Electrical rant .......

by Sagraiasolar Tue Sep 24, 2013 1:50 pm

First topic message reminder :

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

by Panner Fri Sep 27, 2013 2:22 pm

Geotherm wrote:
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 quarterBased 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.

Thanks Geotherm

That's useful, especially the split as to F1 and hot water/heating.

I am looking at a 12KW ASHP (with an average COP of 4 as that fluctuates with outside temperature. (The quoted COP at 7C outside 35C water is 4.69 for the unit I am looking at) - we are in southern Italy where the outside temperatures (on average during the heating period) should be above 0C and average mean temperature Jan/Feb is around 8C (with average lows of 4C and highs of 12C). (worked on 0C in terms of sizing etc). To cover the underfloor heating and hot water have estimated about 6,000 KWh consumption with approx 15% for the hot water. I suspect when it is in and operating in the real world it will probably use less as my calculations were deliberately on the cautious side and used average monthly temperatures for the region from one of the weather sites.

As I am looking at PV as well I need to think about the order of offset and overall level of net useage and what my marginal rate will be on the D3 tariff to work out whether it is worth setting it up so that the ASHP can go on the BTA3 tariff.

With so many variables any calculations are no more than estimates that are hopefully in the right ballpark

by **Geotherm** Fri Sep 27, 2013 3:15 pm

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...

Agree Steve, that they look like aircon units. A lot now are being made in China, so that they can break into the market. The only real difference of the installation of a GSHP to a ASHP in time is the ground loops, as rest of the connection is very much the same.
I would certainly not want something that looks like that in the link you gave Mad

by **Geotherm** Fri Sep 27, 2013 3:30 pm

Thanks Panner. The COP of that unit seems very high @ 7C. Most units are circa 4.0 at that temp, which can drop to around 3 around 2C.
Would be interested if you would send me a PM with the link to it, so I could have a look.

by Panner Fri Sep 27, 2013 4:31 pm

Geotherm wrote:Thanks Panner. The COP of that unit seems very high @ 7C. Most units are circa 4.0 at that temp, which can drop to around 3 around 2C. Would be interested if you would send me a PM with the link to it, so I could have a look.

It is the new Panasonic Aquarea range (came out earlier this year). the 12kw model has a cop of 4.67 at 7C and drops to 3.4 at 2C and (9 KW is 4.74 & 3.53). As I am looking at an output temp of 30 to 32C rather than 35C should be able to achieve an average of 4 over the heating season.

UK link to where you can get details is http://www.panasonic.co.uk/site/en_GB/node/10482636/Len_GB (some of the brochures only show +7 and -7 COPs but others show +2 and -15 as well.

by Sagraiasolar Sat Sep 28, 2013 11:32 am

OK the Excel sheet is done. Please email me on heatingitaly (at) gmail.com and I'll send it off for preliminary checking.
Notes: As Enel measure out the higher rates over the year on a guestimate basis you need to use this over a whole year - checking one bill against it doesn't work.
The change point to go over to ASHP rates is - provisionally - 5,555 kw.hrs. If you were heating a house requiring a typical 25,000 kW.hrs or 8,300 kW.hrs of electricity running an ASHP on a COP of 3 then the saving would be £350 a year.
If you envisage any additional sources like wood and solar then I doubt it would be worth it as the ASHP would be substantially backed off.
N.B. When you go over to the ASHP meter your domestic bill still ticks on although it's good to know that there could be some moving down the scaglione if you are a very light user - under 4400 kW.hrs a year.
Thanks Panner for the data - I had to draw a 24 hr clock and colour in the F1, F2 etc just to get to grips with how it works.

by **ghiro** Sat Sep 28, 2013 12:45 pm

My brain hurts just reading this thread as my knowledge of electricity doesn't extend beyond using light switches and changing bulbs! Sad

by Panner Sat Sep 28, 2013 1:27 pm

2 Aspirin and a cold towel or a bottle or two of wine - then the technical bits just flow over you or you are so happy you don't care

by Flip Sat Sep 28, 2013 2:01 pm

So too sum all this up then, we need to switch off things during peak times and don't waste electricity, have heaters etc on timers so they use off peak tariffs, wear an extra pullover when it gets cold instead of turning the heat up, only use electric ovens when absolutely necessarily, to avoid horrendously high bills ...... common sense then.
P.S.
our last 2 moths electricity bill was €134 and we only have electricity, so we must be doing something right.

by **ghiro** Sat Sep 28, 2013 5:09 pm

Panner wrote:2 Aspirin and a cold towel or a bottle or two of wine -

Definitely going to opt for the latter option! Very Happy

by stevegwmonkseaton Sat Sep 28, 2013 7:38 pm

ghiro wrote:
Panner wrote:2 Aspirin and a cold towel or a bottle or two of wine -
Definitely going to opt for the latter option!

Ok and us as aspirin is far too expensive here.... Very Happy

by **Gala Placidia** Sat Sep 28, 2013 7:42 pm

What about candles? Razz

by stevegwmonkseaton Sat Sep 28, 2013 8:42 pm

Gala Placidia wrote:What about candles?

Ok might stick one or two in the empty wine bottles...

by Sagraiasolar Sun Sep 29, 2013 8:31 am

Flip wrote: P.S.our last 2 moths electricity bill was €134 and we only have electricity, so we must be doing something right.

Ha - Well I suppose the thread was going to break down eventually. €134 sounds quite high for just 2 moths.

by stevegwmonkseaton Sun Sep 29, 2013 9:42 am

Ok back on track as this is a great thread and advert for the forum.... I'm amazed at some of the bi monthly amounts quoted in some of these posts. Of course the amount of electrical devices you have and numbers of people, rooms etc make all the difference, but still some of the amounts quoted are eye watering. We have a 3 bed room place, but normally there is only the 2 of us here. All bulbs are energy saving of the old and new type and we are a bit on the "echo warrior" side of life, so switch off when not in use. No TV, radio, dish washer , pool pump... In fact just the washing machine and electric oven of any note and with the latter we often use the pizza oven in summer instead. Our bill which arrived almost the day this thread started was €32.74 (D2 bioraria rate), last year at the same time the bill was €32.70... Had a quick look back and our bills since being here have always (except for a few times we've been away a few months in the UK) invariably been on or around the €32 mark. Winter we have sanza (olive waste) boiler and wood burning stove in main room. We have all the costs of wood, gas (small tanks for top cooker only) and electric, so I must try to work out what our spend is at some point...

by Panner Sun Sep 29, 2013 1:22 pm

Needs the cost of all those other things to see the true comparative cost between what can be achieved by the "eco warrior" approach and the lesser mortals who rely solely or mainly on electricity and have some of the "luxuries" plugged in

by **Geotherm** Sun Sep 29, 2013 2:52 pm

Sagraiasolar wrote:
Flip wrote: P.S.our last 2 moths electricity bill was €134 and we only have electricity, so we must be doing something right.
Ha - Well I suppose the thread was going to break down eventually. €134 sounds quite high for just 2 moths.

Love it.
The 2 moths must have been very happy with all that heat and light. You should have got a hampster running round a cage linked to a bike alternator, would have been less costly Smile

Anyway, our last Enel bill that has just arrived, came in @ Euro 237 which wasn't that bad, according to us. I did not even reach the level 4 rate!!!

If we switched all the lights on in the bathroom alone here, we would consume 800wh, Kitchen, circa 500, just on lighting alone. Discount the microwave, F/F, dishwasher, 3Kw electric oven, kettle etc. Wife does tend to use the Wm and T/D during the week Mad

Everything depends on the lifestyle that you want, so it is a personal decision. We do have a number of energy saving lights, but most here are 50w halogen.

I must be a lesser mortal Panner:lol: Laughing

by Sagraiasolar Sun Sep 29, 2013 3:25 pm

Panner wrote:Needs the cost of all those other things to see the true comparative cost between what can be achieved by the "eco warrior" approach and the lesser mortals who rely solely or mainly on electricity and have some of the "luxuries" plugged in

yes indeed ... the lower end of the scale must be owned by my chums who are entirely off grid and live in a tent.
However I'm afraid I have surveyed a few systems at the silly end of the scale - €10,000 total energy. As to what is normal I think one first needs to set the height of the hurdle and 25,000 kW.hrs a year for heating is about right for a fairly big rustic stone house here.
5mq of wet solar and €1,200 of wood covers this in most cases. Gas costs 6 times as much. A heat pump would fall in the range 2000 - 2500 and without any log lugging has to be a front runner.
Domestic electrical consumption needs to be added to that of course. Most surveys reveal something that should be sorted out; pool pumps in particular.
It is a sobering thought to think that each 1Watt used for 10 hours a day costs €1 a year. To start eliminating each Watt I like wandering around with an Efergy Elite energy meter which being battery powered can be carried- £40 well spent.

by **Geotherm** Sun Sep 29, 2013 4:23 pm

Have moved this into the property site, as there is so much info, that should not be just in suggestions. If you disagree, then will move it back!!!

by **Gala Placidia** Sun Sep 29, 2013 6:22 pm

This is a very valuable thread. Congratulation to all the brainy members who made all those great contributions (not including myself... but we are all "allowed" a bit of silly humour... Razz

by **Geotherm** Sun Sep 29, 2013 6:31 pm

Of course Gala, there nust be humour, as clinical answers bore everyone

by stevegwmonkseaton Wed Oct 02, 2013 11:00 am

ENEL tariffs are here if you need them ENEL Tarrife LINK

by Vicino Thu Oct 03, 2013 4:59 am

Thanks Steve and others,

This is not causing me enough concern to spend the time to fully understand it all. To try to do that would cost me so much in headache tablets, it would not be cost effective ! Laughing

V

by Sagraiasolar Thu Oct 03, 2013 7:38 am

About that rule of thumb : Every 1W used for 10 hours a day costs €1 a year
I keep finding scary examples around the house. 20W of nightlights is OK I suppose but it was the 30W lava lamp left on all the time that got me .... €72

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