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Cardew

M4ximillion wrote: »

I
I HAVE MONITORED MY USAGE FROM THE GRID SINCE I HAD THE SYSTEM INSTALLED IN FEBRUARY AND I AM USING 40% LESS THAN THE SAME PERIOD LAST YEAR. MY TOTAL USAGE FOR 12 MONTHS PRIOR TO INSTALLATION WAS 4500 (ROUNDED UP, I GOT CONSUMPTION CHART). IF I CONTINUE AS I AM DOING, MY USAGE WITH THE PANELS IN PLACE SHOULD BE 2700KW HOURS. SO, I WILL HAVE SAVED 1800KW HOURS X 12P PER KILOWATT HOUR THAT I AM PAYING AT THE MOMENT = £216. I DIDN'T JUST DREAM THE FIGURE UP.

You keep going on about how you can't possibly use more than 1000kw hours a year and that you have seen proof of this but you offer no proof of it. Also, were the panels the same as the ones ive got? Were all the roofs the same as mine? (and others that asg have fitted on). From the feedback i see on ASG's facebook page and also from their testimonials my experience seems to be the norm. I think solar is much more effective than you say but youre determined not to let the truth out because you can't stand being wrong or anyone disagreeing with you. GrahamC is the same. You just keep harping back to the same figures. Do you ever think that maybe you could be a tad wrong????

I will repeat this once again!

Nobody is disputing that your electricity consumption might be lower this coming year.

Your forecast of a 40% reduction in annual consumption by next February(8 months ahead) might even be realised.

What we are saying is that you have given no rational explanation of the part solar PV will play in that reduction. Plenty of people reduce their consumption without having solar.

I have not stated 'you can't possibly use more than 1000kw hours a year' that is just a figment of your imagination - or perhaps you can show me where I have made such a statement?

What I have said is I haven't seen anyone who has an export meter(which you need to know how much you have used in the house) who has claimed to use more than 1000kWh pa.

It would be very easy to use every kWh you generated. Leave on several 3kWh heaters(and large lights) 24/7 in a sealed room and grow some nice plants!

What I have said is that people will do well to use 1,000kWh pa of PV generated electricity - around £100.

P.S.
Why do you pay 12p per kWh for electricity? Surely you would be far better off getting a cheaper tariff!

Dave_Fowler

Cardew wrote: »

I have not stated 'you can't possibly use more than 1000kw hours a year' that is just a figment of your imagination - or perhaps you can show me where I have made such a statement?

What I have said is I haven't seen anyone who has an export meter(which you need to know how much you have used in the house) who has claimed to use more than 1000kWh pa.

I agree with you. I've had my 3kWp system installed for 350 days now and have tried hard to match the generation of the panels with the power used in the house. My base-line power usage is around 500W - 2 fridges, 1 freezer, computer network and electronics workshop. I have tried to use power when the panels were producing a good output by turning on various loads such as the immersion heater, dishwasher, washing machine and other heavy usage appliances to use the excess power. I'm at home most days and have my own meters reading the panel output and the house consumption. There is a limit to how much energy a house can consume, once the hot water tank is hot, the immersion turns off. Because the import meter runs backwards when I generate more power than I am using, I am able to calculate reasonably accurately the exported power. (Maths posted in another thread on this forum). In the 350 days I have generated 2510kWh, exported a calculated 1352kWh and hence used 1158kWh.

Dave F

grahamc2003

Dave_Fowler wrote: »

I agree with you. I've had my 3kWp system installed for 350 days now and have tried hard to match the generation of the panels with the power used in the house. My base-line power usage is around 500W - 2 fridges, 1 freezer, computer network and electronics workshop. I have tried to use power when the panels were producing a good output by turning on various loads such as the immersion heater, dishwasher, washing machine and other heavy usage appliances to use the excess power. I'm at home most days and have my own meters reading the panel output and the house consumption. There is a limit to how much energy a house can consume, once the hot water tank is hot, the immersion turns off. Because the import meter runs backwards when I generate more power than I am using, I am able to calculate reasonably accurately the exported power. (Maths posted in another thread on this forum). In the 350 days I have generated 2510kWh, exported a calculated 1352kWh and hence used 1158kWh.

Dave F

Dave, Could you take just one more step in your analysis and estimate how much this has actually saved you, extrapolated to an annual saving? I think your experience will put an upper marker on what savings are possible (making reasonable assumptions) - both you and your situation appear to me to be almost the ideal for getting the most from your panels.

As a first cut (the type often done on here, usually accurate enough given the usual inaccuracy of the source data), obviously it looks like around £120 annual saving (this year), but your data above can be refined further.

Obviously water heating would have a value of your alternative cost of water heating, and also there must be an element of sometimes running the immersion (3kw?) when there's only a 1kw(eg) surplus, so sometimes a probability of a net financial loss of doing so, even if just for a few minutes (obviously these are dynamic systems with one minute a 2kw surplus, the next minute a 1kw surplus, the next minute a possibility of a 3kw import from the grid (for example, depending on what's happening).

Also, I'd be interested in your views on the average person's financial saving from solar energy used in the home, or perhaps an estimate of the range of savings realistically possible (the lower bound imv would be someone with a low 'background' usage, and out at work between 8 and 6 but with a timer set for a lunchtime clothes wash, the upper being your situation, imv. (my estimate would be something like £70 lower to £120 upper with the info I have atm.).

Thanks in advance if you could take the time to do this.

Dave_Fowler

grahamc2003 wrote: »

Dave, Could you take just one more step in your analysis and estimate how much this has actually saved you, extrapolated to an annual saving? I think your experience will put an upper marker on what savings are possible (making reasonable assumptions) - both you and your situation appear to me to be almost the ideal for getting the most from your panels.

As a first cut (the type often done on here, usually accurate enough given the usual inaccuracy of the source data), obviously it looks like around £120 annual saving (this year), but your data above can be refined further.

Obviously water heating would have a value of your alternative cost of water heating, and also there must be an element of sometimes running the immersion (3kw?) when there's only a 1kw(eg) surplus, so sometimes a probability of a net financial loss of doing so, even if just for a few minutes (obviously these are dynamic systems with one minute a 2kw surplus, the next minute a 1kw surplus, the next minute a possibility of a 3kw import from the grid (for example, depending on what's happening).

Also, I'd be interested in your views on the average person's financial saving from solar energy used in the home, or perhaps an estimate of the range of savings realistically possible (the lower bound imv would be someone with a low 'background' usage, and out at work between 8 and 6 but with a timer set for a lunchtime clothes wash, the upper being your situation, imv. (my estimate would be something like £70 lower to £120 upper with the info I have atm.).

Thanks in advance if you could take the time to do this.

Hi Graham. It's almost like being back at school and having some homework set!

In order to make any reasonable effort to calculate savings I have to consider the set-up before the PV installation. Water heating was only done by the gas central heating boiler (modern condensing). Probably quite efficient when central heating is on, but less efficient during summer when no central heating. Electric supply is on economy 7. Washing machine and dishwasher timed to be on at night rate. I am currently on a capped rate for both gas and electric. This was set before I had the PV installed and is probably not the best now - cap due to end next month.
Electric primary units are 23.12p per kWh and secondary at 9.21p per kWh. Gas is primary 6.8p per kWh and secondary 2.02p per kWh. All exclusive of VAT at 5%.

As I mentioned in my last post, my meter runs backwards when I export electricity. The supplier is aware of this, but I don't want to remind them by producing very low or negative meter readings. During the winter months I used the pre-PV installation method of energy use as there was only a few short times when there was an excess in production. Energy bills were reduced mainly by the lower imported supply. It has only been during the last three months (April, May, June) when I have had to use more energy during the daytime otherwise I would have exported much more than I imported and had a negative electricity bill.

During the winter months October - March I generated 745 kWh total, of this 385 kWh was exported. I.e. I used 360kWh. All of this would have been at the 9.21p rate - Just over £33 saved in 6 months by the reduction in imported electricity.

Moving on to some summer months, in the last 3 months (less 2 weeks) I have generated 910kWh and exported 469kWh, therefore used 441kWh. My import meter says I have imported 165kWh in the same 3 months. Remembering my meter goes backwards, my total usage is therefore 910+165 = 1075kWh. I know you can not compare one year with the next, but in the same period last year - before the panels were installed - I imported 689kWh. Much of the difference can be accounted for when I use a 3kW immersion, washing machine or dishwasher but only generate an excess of 2kW. Last year the cost would have been made up of 250 kWh at the primary rate of 23.12p plus 439 at 9.21p = £98.23. This year the bill should have been 1075kWh= £134, a loss of £36.*

Looking at my night-time electricity consumption over the same period: last year 314, this year 267 (Difference due to pumps and motors and water heating in washing machine and dishwasher last year?). A saving of 47 x 4.81p (night time rate) = £2.26. The 3 month gas consumption last year was 1209kWh, this year 728kWh - a vast difference, but I suspect mainly due to the warmer weather in April this year and nothing to do with the panels. Changing the dates of the readings I use to a time when the central heating was definitely off, but I was still using gas to heat the water, I was using 51kWh of gas per week. This year, when there was no central heating this has reduced to 40kWh per week. At 51 (or 40) kWh per week, all the gas would be at the higher cost/kWh rate so over a 13 week period, I will have saved (51-40) x 13 x 6.8p= £9.72p.

Deep breath. Conclusions:
Winter 6 months October to March, rough electric savings £33, Gas £0
Summer 3 months April to June, rough electric saving of £-36, Gas £10

Assuming I continue to use the same strategy for the next 3 month of summer, I may lose a further £16, giving a total for a year of £1.

*The actual bill was for April - June is 165 x 23.12p = £38.15, a saving of £60.08 for the three months giving a projected annual saving of 2 x (£60 +£10) + £33 = £173.

But what happens when my meter is finally changed for a proper modern meter? I certainly wont be turning on the immersion to use up the spare energy, not when the import rate is 21p per kWh and the saving on gas is only 2p per kWh. I expect my baseline level of 500W will be provided for during the average 12 hours of sufficient daylight during the summer months = 6kWh per day for 180 days = a saving of 6 x 180 x 9.21p = £99.47. And then £33 for the winter months. £133 per year.

Sorry It's taken so long, but you did ask!

Dave F

furndire

T:T:T:TA round of applause - that certainly must have taken some time working out :T :eek::

grahamc2003

Yes indeed, 10/10, one house point!

Thanks for all that effort, just shows how many factors have to be taken into account to reach a reasonable estimate of savings, even after you have all the generation data. I'll get back later when I have the time to absorb it all.

magyar

John_Pierpoint wrote: »

Am I right in thinking that the gear box in a wind generator lasts 10 years if one is lucky ?

You're right that gearboxes have historically been a weak link, but it's not as bad as that - we would normally factor in a gearbox replacement on about 25% of our turbines over their 20 year life.

Newer turbine designs are using direct-drive technology which doesn't have a gearbox so the problem will eventually go away.

HalloweenJack

so who do you work for maygar - given your statement

in a gearbox replacement on about 25% of our turbines over their 20 year life

would mean yo work in teh wind farm industry - and thus would naturally be opposed to Dr Carpenter.....

magyar

HalloweenJack wrote: »

so who do you work for maygar - given your statement



would mean yo work in teh wind farm industry - and thus would naturally be opposed to Dr Carpenter.....

I have never hidden the fact I work in the electricity industry, I don't solely work on wind power but I do specialise in renewables. I am not going to say specifically who I work for.