Solar Panels - Energy Saving

EricMears

Martyn1981 wrote: »

Originally Posted by Martyn1981
Do you think a 450kWh cap makes sense, reflects typical import savings?

I've had a nice chat with the EST who stand by the numbers, citing government research. They say the average saving is 450kWh.

I pointed out that that's just baseload, they said baseload is 81W, I countered with what about central heating pumps more likely to be running during the day, and fridges/freezers warmer in the day etc, but they were unmoved.

I would suggest that the purpose of the 'cap' is to prevent unscrupulous salesmen from claiming higher than reasonable savings. Whilst I agree that their baseload seems a lot lower than mine, I think I support the idea of them insisting that the lowest likely figure is used. But I'm pretty sure that salesmen will get round that by saying that many people have higher baseloads - however, the onus would be on them to convince the punters that theirs is a high baseload house and surely they'd ask them to justify such a claim ?
(No idea why this post is stuck in italic ! Clicking on the I button doesn't cancel.)

jimjames

Kevinwebster wrote: »

Hi and thanks for all the comment, the system basically comes with two batteries so stores the power for me to use so little or none will go back to the grid, that could be why the price is higher. According to the rep all the deadliest have to be confirmed by three other parties, including MSE people, because Martin Lewis would agree it any other way. Is there anyone from MSE who can validate the figures? Could 16 panels really generate 3735 kWh which could be stored and therefore I would not need to use the grid and pay my supplier, which could save me circa £600 per year. I am also a but confused that in the MSE website it indicated the Government scheme indicate the could be free, but I am being told it is 10k which I need to take a loan for.

I think you can safely say if you're being told it's agreed by Martin Lewis then you're being ripped off. MSE do not sell solar panels.

Martyn1981

Thanks guys, interesting thoughts.

Eric, I mostly agree about aiming/suggesting a bit low, so as not to mislead folk, but the EST's numbers aren't a minimum, they are saying that 450kWh and 81W are average, which seems very strange to me.

They did say that the baseload is measured between 3am and 4am, so it would exclude the central heating pump when the heating is in operation, which could double that figure. But I can't think of anything extra in the summer months, other than perhaps a hotter house causing the fridge/freezer compressors to work harder during the day, but that's a long shot.

I wish my baseload was 81W?

Mart.

EricMears

Martyn1981 wrote: »

I wish my baseload was 81W?
Mart.

Seconded !!!

pinnks

Thirded - is that even a word?

Anyway, the lowest I have ever seen my usage is 130W and that is real base load - no fridgefreezers cooling or pumping, no TVs actually on etc etc.

Fridges on "sleep" consume about 21W between them, Virgin box about 15W, phones, TVs, alarm and other clocks etc another 15W or so, and so the list goes on...

Martyn1981

I've found the government report that says 81W, and above it 47W which the EST also mentioned. It's on page 397 of this report:

Household Electricity Survey A study of domestic electrical product usage

I was talking baseload, the EST did say stand by in response to my 120W(ish) claim, so there may be some confusion over the terms, but it was cited to say my number (guess) was too high.

I note that on page 263 it says the average fridgefreezer uses 427kWh pa, which is an average of 48W on its own.

Just changed my boiler water pump speed from 2 to 3 (I do this to protect the heat exchanger in the summer, but to prevent whistling at the TRV's in the heating months - I think my boiler is a little too powerful). Anyway's the pump settings are 40W, 65W and 90W, and these consumptions (when the heating is on) wouldn't be shown in the survey which was carried out between 3am and 4am.

The problem now, is that I'm getting more confident that 450kWh of import reduction should be a minimum not an average, if baseload is higher than they claimed. So still no nearer to understanding why the average savings are set so low.

I wonder what the results of a survey comparing generation to export (smart meter) would show? Obviously excluding those with diversion switches. That should give a genuine PV consumption/import reduction figure.

Mart.

Martyn1981

And here's the report (page 10) concluding 450kWh of PV consumption. It actually says households with PV reduced import by 900kWh, but a test group without PV reduced demand by 500kWh during the same period 2011-2013.

I'm obviously having a confused day, as this report has surprised me. The non-PV household reduction is 10%, that is of course entirely possible (low energy lights, more efficient fridges and freezers, and lower consumption TV's).

However, these energy reduction items have been available for decades, so why would the test group, on average, all reduce demand by 500kWh during the 2011-2013 period? Why not before, during and after.

If it's a genuine comparison, then it must be true, but it seems statistically impossible?

Mart.

zeupater

Martyn1981 wrote: »

Well, where to start.

I've had a nice chat with the EST who stand by the numbers, citing government research. They say the average saving is 450kWh.

I pointed out that that's just baseload, they said baseload is 81W, I countered with what about central heating pumps more likely to be running during the day, and fridges/freezers warmer in the day etc, but they were unmoved.

So 81W x 10hr average per day (fair?) x 365 days = 295kWh that can't really be avoided no matter how hard you try. Then even for a house empty during the day, you have summer evening use and weekends when folk are home and consuming/saving more.

So 450kWh is an average of 295kWh up to XXXXkWh.

I pointed out that logically I was struggling with this average since my reduction of about 1,400kWh would need about 3 people on zero savings to average out. Thinking about it, it would take 6 households on 295kWh to balance me out.

I also added that those I chat with on MSE or renewables forums, with PV, seem to have reduced consumption far more, but they countered (quite cleverly I feel) that such people are environmentally or financially motivated to do better than the average person. I mentioned that I'm both environmentally and financially motivated, but don't really try hard at all, it just does what it says on the tin.

Does this sound fishy to anyone?

Mart.

Hi

It's not fishy at all ... if the EST "stand by the numbers, citing government research. They say the average saving is 450kWh." ... then I'll simply call it as it is - it's utter MBE (Male Bovine Excrement, or bullsh1t) - I'll also challenge both the EST & their sources to justify that it's not ....

Taking the average day daylight hours as being 12hrs, then 450kWh represents (450/365/12), so just over 100W average power consumption during the day, which is absolutely ridiculous ...

Okay, so let's test the assumption with a single technology, refrigeration, by taking a random and representative consumption from the efficiency labels available at product sale which are based on EU approved test cycles, so something which the EST and everyone else have ready access to themselves ...

A+ rated under-counter = (F)188+(R)113 = ~300kWh/year
A+ rated fridge/freezer = ~260kWh/year
A+ rated 'American' style = ~400kWh/year
A+ rated large = (F)325+(R)143 = ~470kWh/year
A+ rated medium chest = ~260kWh

... Okay, taking the above spread and plucking a figure to use as a 'brand new' average usage we probably get to somewhere around 360kWh/year (totals/4) excluding the chest freezer. Remember, these are figures representing new appliances, so allowing an average ~20% efficiency drop over the appliance lifetime we'll add 10% (through-life average) which gives us a pretty fair ~400kWh/year average .... let's be ultra fair and say that summer & winter operating temperatures are equal (which they're not!) resulting in equal cooling demand, then over the 12hrs of average daylight refrigeration alone consumes ~200kWh .... almost half of the ridiculous assertion which they stand behind ...

It looks to me that someone who employs intellectual lightweights to perform 'research' has come up with more of the same - it'll probably be the EST themselves, if not then DECC and/or the BRE would be running closely behind ... so I'll repeat my challenge to the idiot(s) who came up with the figure .... either provide proof which would be typical to the average UK household which is capable of having a stand-alone pv system, or accept that you're wrong and simply peddling male bovine excrement ...

HTH
Z

Martyn1981

Hiya Z. What are your thoughts on the study that finds only a 450kWh reduction when the control group is taken into account?

I can't argue with a genuine study if those are the findings, but I'm confused by the control groups significant savings within the comparison period.

Can you think what might have gone wrong, or is it us?

Mart.

EricMears

Martyn1981 wrote: »

I can't argue with a genuine study if those are the findings, but I'm confused by the control groups significant savings within the comparison period. Mart.

It's a well know trial effect - closely related to 'White Coat Syndrome' in the medical world.

I used to do a lot of testing of various additives in the cement grinding process. It quite often happened that when we tested something we all agreed couldn't possibly have any effect (e.g. dribbling a few mls per minute of pure water onto the feed belts which carried materials of varying intrinsic moisture of their own) there was more often than not an apparent improvement in grinding efficiency. This was generally ascribed to operators taking extra care because they knew the test was being monitored more closely than on normal days.

I'd suggest it's quite likely that when a government inspector knocks on a door and tells occupant he wants to monitor your electricity usage he'd very likely take special care to switch off lights when he left a room, only half filled the kettle to make one cup of coffee etc. etc. OTOH, if the same inspector knocked on my door or yours we'd probably have no 'special steps' left to take.