Free solar panel discussion

zeupater

cathd6 wrote: »

Thanks for the polite post.

I genuinely don't have my monthly figures here (and I feel much more inclined to make the effort to show them to you than some others around here! The meter is not far from my seat and I've posted total generated above) but one obvious point from the Wembury figures you've posted above. February is showing far better than December, despite you saying, quite correctly, that it was abysmal. For us, December wiped the floor with February. Are those figures correct?

We have exceeded forecasts for every month so far, so I appreciate that we are doing particularly well. As I've already stated we probably couldn't have a better set-up. It is "only" 4kwp tho - no point installing more than that, is there.

Hi

The way you need to look at the figures is that PVGIS is an average taken over a number of years and is quite accurate down to a very small area resolution .... the latest dataset is based on satellite data collection and is the one used to calculate the figures which I used and will therefore reflect your specific location (Devon, that's why I chose Wembury for the example .... I know the county quite well). The SAP calculation is based on an average for the entire country and would probably only be correct for somewhere around Sheffield(ish). The Met-Office anomaly charts can be used to flex the actual performance of your system by a percentage based on sunshine to a nominal figure in order to gauge performance .... this is how many with systems keep an eye on them, and you can quite easily use the combination of these two data sources to explain why in your case, and that experienced by many others, for last winter December outperformed February.

Many pv system owners publish their generation data on comparison sites in order to directly compare with other systems. This is usually done in the form of kWh/kWp and is also compared against a nominal dataset such as PVGIS or website average. There are owners who have systems in Devon to compare your system against on at least two of these sites that I know of. There are also people who have fitted equipment to their systems in order to publish their generation to the web, there's one who posts on this forum quite regularly, so possibly expect an "it's me" soon.

I know that it is nice to have pv and those who have it become a little defensive of their decision in order to self-justify, I do it too at times, and it is possible that there are some posts regarding renewables on this forum which are a little abraisive at times, but you'll find that with reflection many of the posts are by individuals who are actually utilising knowledge & experience in order to try to help others understand what is, and what is unlikely to be, possible.

My 4kWp system isn't in such an ideal location as yours and doesn't face due South, however this is only likely to give your system a 25% advantage over mine when averaged over time, it is this and the ability to flex short term data by referencing the met office anomaly data & maps which cause me to question your savings .... in this field there's likely, there's possible, then there's outrageous. On a 4kWp system located in Devon averaging 300kWh/month over a year is likely, 400kWh/month over a year is possible in a good year, but to actually achieve between 300kWh & 400kWh in December, January & February is beyond unrealistic.

Add to this the savings on self-generated electricity used in the house, which to save £400 on a 4kWp system would mean that you would be using 100%, or close to 100% of production. The only way that you could possibly achieve this would be to ensure that you can effectively mirror household consumption to generation at all times .... or .... have a very high base load whenever it's light, something like well lit retail premises using display-stand spotlights.

HTH
Z

cathd6

grahamc2003 wrote: »

When you first posted the £100 in 3 winter months saving you did not state that it wasn't proof of anything - it was posted (as most of your incorrect views are) as a matter of fact.

It is a matter of fact that our electricity bill for the first quarter post-installation was £100 less than previous. Nothing else in the household changed over that time. That's the only claim I've made. Anything else is down to your own reading.

It shouldn't need pointing out (although I've done it) that this is not a scientific method, as I expect most people on here have the basic level of education required to understand that. It's a more than reasonable guide though.

And it's not reasonable to paraphrase any statements I've made as "wind power is decoupled from fast reserve". If you want to challenge me then challenge what I actually said (which I believe in this case was "It is baloney that Denmark's success with wind power is premised on high availability of hydro power and that this alone makes wind power viable" Spot the difference. And somehow I don't think you're going to want to be challenging that one.

I'm not going to be intimidated into digging out the monthly figures. I don't have anything to prove and tbh you wouldn't believe them anyway, would you? If you don't want to believe me that we've generated 2253 over 6 months, well, that's entirely up to you. "Hello darling, what are you doing?" I'm just spending half an hour looking up some data from our spreadsheets to win a !!!!ing contest on an internet messageboard" Erm, no! :cool: I'm happy to receive a PM from anyone who is genuinely looking to make this kind of investment and offer advice based on our experience.

On the other hand we have sent our data to both the Sheffield University project and to one further site measuring ROI. I'd be happy to share those links when they appear.

cathd6

zeupater wrote: »

but to actually achieve between 300kWh & 400kWh in December, January & February is beyond unrealistic.

I'm sure that we didn't. With 2253 over 6 months that would mean we generated the same over Dec-Feb as we did over March-May. Dec was close to one of the "warmer" months

I've only claimed to average 300-400/month, which is on the low side looking at the actual figures.

I know for fact though that the Dec-Feb total was well over 500 - even looking at the total generated it's very clear that it would be implausible that we'd generated 1700 over the other three months.

If we do save £400 this year it will be a very good year indeed, and I have no expectations that following years will be the same. In the meantime :beer:

There is a very clear question here which I'm still waiting for someone to ask, and the answer is "I honestly don't know", but all I have done is post some facts about our situation and no doubt as the year goes on things will settle down and we'll have a good picture. As I've said above, our data's going to be on a couple of sites soon.

The real context was a few people whose mindset towards renewable energy development could be compared to "Computing machines! At home? Nonsense, how would they ever be affordable and where would you keep all those damn punchcards?"

grahamc2003

cathd6 wrote: »

And it's not reasonable to paraphrase any statements I've made as "wind power is decoupled from fast reserve". If you want to challenge me then challenge what I actually said (which I believe in this case was "It is baloney that Denmark's success with wind power is premised on high availability of hydro power and that this alone makes wind power viable" Spot the difference. And somehow I don't think you're going to want to be challenging that one.

I'm not going to be intimidated into digging out the monthly figures.
.

Well yes, you're correct, I don't want to 'challenge' you on your statement. But not for the reasons you think. I could explain (yet again) why your view is incorrect, but you are in the frame of mind not to accept any form or reason (maybe you are always in that frame of mind possibly), so it would be pointless, plus I have already explained this point.

On the second point, why do you describe posting your meter readings as 'intimidation'? It's always the very first thing requested when people make any sort of claims such as 'NPowr are ripping me off', 'why is my bill so highy' and 'I saved £500 this month alone from my solar panels' (and tbc, I'm not saying you nhave said those things, they are just examples). No one else I have read about has ever objected to posted readings or accused others of intimidation when requested, and I wonder why that simple (and obvious) request has produced that reaction in you.

Anyhow, I'll leave the discussion now, so I wish you good luck with your panels. One thing more though if you don't mind - would you mind disclosing if you or family have any vested interest in solar or any other renewable energy? No need to answer if you feel this is intrusive and, as I said, I won't reply further anyhow whatever your situation.

Cardew

cathd6 wrote: »

It is a matter of fact that our electricity bill for the first quarter post-installation was £100 less than previous. Nothing else in the household changed over that time. That's the only claim I've made. Anything else is down to your own reading.

Are you seriously suggesting that you were not implying that the £100 saving in a winter quarter was down to your PV installation?

zeupater

cathd6 wrote: »

I'm sure that we didn't. With 2253 over 6 months that would mean we generated the same over Dec-Feb as we did over March-May. Dec was close to one of the "warmer" months

I've only claimed to average 300-400/month, which is on the low side looking at the actual figures.

I know for fact though that the Dec-Feb total was well over 500 - even looking at the total generated it's very clear that it would be implausible that we'd generated 1700 over the other three months.

If we do save £400 this year it will be a very good year indeed, and I have no expectations that following years will be the same. In the meantime :beer:

There is a very clear question here which I'm still waiting for someone to ask, and the answer is "I honestly don't know", but all I have done is post some facts about our situation and no doubt as the year goes on things will settle down and we'll have a good picture. As I've said above, our data's going to be on a couple of sites soon.

The real context was a few people whose mindset towards renewable energy development could be compared to "Computing machines! At home? Nonsense, how would they ever be affordable and where would you keep all those damn punchcards?"

Hi


Going back to the £100 electricity savings .... is it possible that the £100 saving is over 2 quarters .... this older post (23/05) (http://http://forums.moneysavingexpert.com/showpost.php?p=43864818&postcount=14) suggests that the system was installed in November and that you are "owed over £100 for electricity saved so far", that would be over six or seven months, not three. Allowing for some basic energy saving techniques (such as using standby less), whether consciously, or subconsciously, the saving becomes more plausible.

Looking at the figure of 2253kWh. Without knowing the source of the figure, I'll assume that it's the total generation meter reading and that it was yesterday's reading, also assume that the installation was in mid-November. Taking a location as being Wembury, Devon and let's say a 10% system loss instead of the usual 14%, we achieve the following generation prediction using PVGIS/C-SAF....

---

Latitude: 50°19'34" North,
Longitude: 4°5'11" West
Nominal power of the PV system: 4kWp
Inclination of modules: 35deg.
Orientation (azimuth) of modules: 0deg.
Fixed angle
Month/kWh
1 157
2 214
3 395
4 497
5 543
6 535
7 512
8 494
9 425
10 280
11 214
12 139

Monthly Average 367
Annual total 4400

---

Therefore, on a system installed mid-November, a generation reading taken mid-June would be .... (214/2)+139+157+214+395+497+543+(535/2) .... which equates to 2319.5kWh of generation, which is almost spot on with your 2253kWh figure.

I hope this helps explain that simply taking the total generation and dividing by the number of months and arriving at an answer between 300kWh & 400kWh per month does not mean that you would generate the average every month.

I know it's crude, but without data assumptions need to be made, however, the figures are in the right ball park. There could be timing issues at the beginning or the end of the period, depending on the installation date & the date of the 2253 reading, but then again, there were very good generating periods in the Spring which would compensate .....

HTH
Z

HalloweenJack

gosh

http://forums.moneysavingexpert.com/forumdisplay.php?f=100

read that forum - apparantly your system saving£100 over winter is magically betetr than the YEARS worth of data present in the above forum link..... they get anything from nothing saved to not alot - but your system is amazing and saves you money in the dark overcast winter....


does it work well with snow on the panels as well?

edit:


whats of more interest is the redution in subsidies to the `green field renewables` - those ppl who are build mega watt installations in fields , then claiming the domestic tarrifs - the climate minister isnt too impressed with this - and one reason why the scheme is being looked at , in depth , again.

apparantly `small scale` is defined as 5 MW - the output of the worlds first commercial atomic reactor at Obninsk was lessso the `indusrty` is up in arms over the reduction in putput from 5mw to 50kw ; sorry but thats damn right - if you want to make a power station , you get paid at those rates rather than the much MUCH higher domestic rates.


edit:

if you havent read it its:

http://www.fitariffs.co.uk/library/regulation/110609GovtResponse.pdf

for all installations over 50kw or those which are stand alone , its now `large scale` pv and not domestic - thankfully someone has seen sense.

As an illustration of the financial constraint, we estimate that every 5 MW solar PV scheme would incur a cost of approximately £1.3m per year for the scheme, which means that 20 such schemes would incur an annual cost of around £26m, money that could support PV installations for over 25,000 households.

HalloweenJack

everyone around the world is looking at the `facts` given to them by experts - and stunningly , most countries are reducing the money paid out , not only on solar but wind as well - seems too many ppl are growing money for not much return.

australia is another country reducing payments - the numbers dont add up to all the hype.

cathd6

Hi zeupater. The system was installed end Nov, began operation 1 Dec exactly. Latest reading was from June 1. Electricity bill was for the last quarter received which almost ties in with 1st 3 months of operation - due next bill any day so will be interesting. Bill differential now claimed and banked - over £100.
I'm aware that generation will be lower in winter months point was that 500 over first quarter would be implausible as this would indicate 1700 for 2nd. If you look at your figures above the total Mar - may is1400.
If anyone would like the full details on how much we've saved and sold back then again, Pm me and I'm really happy to give them to help with your decision. Suffice to say,we're very happy.

cathd6

Cardew wrote: »

Are you seriously suggesting that you were not implying that the £100 saving in a winter quarter was down to your PV installation?

I wouldn't have thought anyone would assume that, no.I seem to have been proved wrong though.
It wasn't £100 and 0 p eitherif anyone's also confused about that use of generalisation