Free solar panel discussion

Cardew

cathd6,

Notwithstanding I cannot understand your reluctance to post figures for your winter quarter, can you at least explain how you 'calculate' any saving figure for in-house consumption.

The only way to calculate that figure is to have an export meter e.g. generated 1,000kWh, exported 750kWh so 250kWh used in house.

As posted elsewhere in this forum, there are a couple of posters who have had their systems for several years(before introduction of FIT) and are 'solar enthusiasts'. Both have export meters and can accurately calculate in-house consumption.

One used 1,000kWh of his generated power in a year and the other 500kWh - the latter having wife and two children at home all day. So that equates to £100 and £50 savings a year.

furndire

Cath6 "On a more interesting topic which is closer to the reason I first posted!! what do people think about yesterday's press on the falling cost of solar panels which would make non-subsidised solar viable in the near future? To a layperson this would appear to be a cautiously optimistic sign that FIT was having the desired effect."


That can only be a good thing - so long as panels perform as well - I don't know if its possible to cut corners in manufacturing them i.e. making them less efficient - hopefully not as in the case of a lot of things that become cheaper quality goes down.

By the way, our panels are one of Nangs case studies - unfortunately I can't tell how much I have saved on electric, because of my meter situation.

cathd6

Cardew, more assumptions - firstly that my household is not of the nerdy variety (I'd consider that a big leap when you know the main academic interests within are physics and linguistics and you couldn't get much more geek!), and secondly about activities within. It's not so unusual to have kids at home - ours both under 4, and I run my business from home. And remember that your bill is reduced by 100% of the energy you produce in any case - by a much smaller proportion for energy you don't use yourself (although I wouldn't put it past anyone on here to have a REALLY bargain basement arrangement!) but it still adds on, and is also good for your halo.

I have no problem conceding on the figures if you like. It's not an argument I'm interested in, it's an aside which is only indirectly related to what I came here to say, and I'm happy for you to choose to reject the two specific mentions I've made - why wouldn't you? it's your call! I don't have any personal investment in their believability,I've said nothing that stands or falls on them and only have a financial interest in terms of my own bank account. I'm very happy that our system is doing so well. As only one example of how this year is outperforming we generated 190 in a month where 130 has been given here as an expected figure,and this is similar to the improvement on our own personalised forecasts from time of installation. (NB to the cautious - forecasts are likely to give a good indication of an AVERAGE year - don't take a single year in isolation and (this is the point you missed before, Dave) USE the forecasts, and also go to a site where you can get a good range of data from a similar set-up for comparison)

I'm sorry if I've offended you in any way. I'm only repeating myself now so I consider this closed. On with your victory celebrations!

Dave_Fowler

cathd6 wrote: »

Cardew, more assumptions - firstly that my household is not of the nerdy variety (I'd consider that a big leap when you know the main academic interests within are physics and linguistics and you couldn't get much more geek!), and secondly about activities within. It's not so unusual to have kids at home - ours both under 4, and I run my business from home. And remember that your bill is reduced by 100% of the energy you produce in any case - by a much smaller proportion for energy you don't use yourself (although I wouldn't put it past anyone on here to have a REALLY bargain basement arrangement!) but it still adds on, and is also good for your halo.

I have no problem conceding on the figures if you like. It's not an argument I'm interested in, it's an aside which is only indirectly related to what I came here to say, and I'm happy for you to choose to reject the two specific mentions I've made - why wouldn't you? it's your call! I don't have any personal investment in their believability,I've said nothing that stands or falls on them and only have a financial interest in terms of my own bank account. I'm very happy that our system is doing so well. As only one example of how this year is outperforming we generated 190 in a month where 130 has been given here as an expected figure,and this is similar to the improvement on our own personalised forecasts from time of installation. (NB to the cautious - forecasts are likely to give a good indication of an AVERAGE year - don't take a single year in isolation and (this is the point you missed before, Dave) USE the forecasts, and also go to a site where you can get a good range of data from a similar set-up for comparison)

I'm sorry if I've offended you in any way. I'm only repeating myself now so I consider this closed. On with your victory celebrations!

Did you mean that about your bill being reduced by 100% of the energy you produce? The only way this can happen is if your meter runs backwards. For most people with a modern meter the bill is only reduced by the power actually used and that has been the point raised in many of the discussions. It is very hard to match ones peak production to ones usage especially if you don't have a minute by minute readout of the panel output power to monitor constantly and adjust the load.

I expect the older meters are due for changing soon.

Dave F

zeupater

cathd6 wrote: »

.... As only one example of how this year is outperforming we generated 190 in a month where 130 has been given here as an expected figure,and this is similar to the improvement on our own personalised forecasts from time of installation. (NB to the cautious - forecasts are likely to give a good indication of an AVERAGE year - don't take a single year in isolation and (this is the point you missed before, Dave) USE the forecasts, and also go to a site where you can get a good range of data from a similar set-up for comparison) ....

Hi

That's really the point that everyone seems to have been making all along .... you have a forecast performance, then you have actual (historical) performance, which can be gauged against a forcast which can be flexed to a degree using Met-office sunshine data.

Looking at the above, the only reference to any where near 130kWh for a month in this recent debate was made by myself deriving this from PVGIS data for the theoretical Wembury system. If you were to follow the logic of flexing the data you would see that the calculated likely production for Dec'10 would have been 178.5kWh (Dec : 139+20% = 167+6.9%assumed panel tolerance adjustment), therefore using your actual 190kWh the margin of error between the Wembury flexed figures and your own is 6.4%, not the 46.2%(190/130) which is being described above. It is likely that around 2.5% of this difference would be due to December'10 daytime max temperatures averaging a whopping 4.91C (HadCET) colder than average (as mentioned earlier in the discussion) and therefore raising the panel efficiency and therefore likely output to 183kWh (178.5+2.5%), so the realistic margin for error on the calculated performance v actual for the month being reduced to 3.8% (190/183) .... I would consider this to be pretty accurate.

Analysis over, I have a relevant question. Can you explain the following from the same post .... " And remember that your bill is reduced by 100% of the energy you produce in any case - by a much smaller proportion for energy you don't use yourself " .... that's not exactly how I and others understand the FiT scheme to work, and I and others have system too, so, how exactly does the logic behind that statement stand up to inspection ?

HTH
Z

lanstrom

Is it still true that the FiTs payment will be reduced in April 2012, and therefore purchasing an installation just before (therefore getting the panels at a reduced rate due to price drops) would be a good idea ?

A sales guy told me that the panels are dropping in price quite a bit now ... dunno what 'quite a bit' means though ?!

Thanks.

KevinG

lanstrom wrote: »

Is it still true that the FiTs payment will be reduced in April 2012

Yes, and every April thereafter.

Cardew

lanstrom wrote: »

Is it still true that the FiTs payment will be reduced in April 2012, and therefore purchasing an installation just before (therefore getting the panels at a reduced rate due to price drops) would be a good idea ?

A sales guy told me that the panels are dropping in price quite a bit now ... dunno what 'quite a bit' means though ?!

Thanks.

Yes the FIT payments are due to reduce slightly for PV systems registered after 01 April 2012.

Just a note of caution it is possible that the Government could review future FIT rates for new systems as they have just done for large commercial PV systems.

Prices have certainly reduced over the past few months around 15%???

zeupater

lanstrom wrote: »

Is it still true that the FiTs payment will be reduced in April 2012, and therefore purchasing an installation just before (therefore getting the panels at a reduced rate due to price drops) would be a good idea ?

A sales guy told me that the panels are dropping in price quite a bit now ... dunno what 'quite a bit' means though ?!

Thanks.

Hi

Yes & yes, however, I'd guess that there will be a temporary halt/reversal of the trend later this year and early next as the installers will undoubtably try to cash-in on a period of supply control over demand prior to the FiT reduction cutoff date.

HTH
Z

lanstrom

Is there anyway to trigger white goods to come on when there is a sustained instance of sunshine ?

Seems to me that just 'setting a timer' is a waste of time as after looking at some graphs it would be very hard to predict when to set it for, and I cant believe that it wouldnt be possible to get the surge in energy to kick off a 'special' switch or even an IP based system whereby the incoming datacapture could kick it off after a certain threshhold ?