Feed In Tariffs(FIT) Announced.

Cardew

penrhyn wrote: »

Tesco actually publish the cost of their Solar Water and Solar PV systems!
Hows an old cowhand going to make a buck now?
http://www.tescohomeefficiency.com/renewable-energy/

Back to the snake oil then.

Nice to see some indication of prices - although it would be crazy to fit a 4.2kW system and thus get the reduced FIT of 36.5p/kWh.(which Tesco point out)

Just as well that for the savings figures Tesco state(in the small print that I suspect many will not read):

These figures are for guidlines only and should not be relied upon.

They take a figure of 14p/kWh which is about 40% more than present prices!

They assume inflation will be 2.4% year on year for 25 years - that may be reasonable?

They assume that electricity prices will rise by 5% year on year for 25 years. - that may be reasonable???

Of course nothing will go wrong with the panels/electronics/mounts/cables/inverters in 25 years so that cost factor can be ignored in their calculations. However they are so confident of the reliability, that the system has, what? a 2 year warranty?

Finally it seems that it would be inconvenient to include any interest lost from investing the installation costs or interest paid on borrowing.

I have little doubt that after 25 years you will be in pocket, but come on Tesco!!!

zeupater

penrhyn wrote: »

Tesco actually publish the cost of their Solar Water and Solar PV systems!
Hows an old cowhand going to make a buck now?
http://www.tescohomeefficiency.com/renewable-energy/

Back to the snake oil then.

Hi

Read it, very interesting and has changed slightly since I last looked ..

One question arises though ... the claim that the system size (kWp) is based on the output of the panels x the number of panels and that the 4.2 kWp system is 24 panels (ie 175W) therefore the FIT, being over the 4kWp threshold, reduces one band to 36.1p/kWh produced .....

I have it at the back of my mind that the FIT threshold is based on a net export AC production not the gross DC nominal capacity, therefore the efficiency of the GTI and the entire system should be included. If the nominal efficiency of the GTI was to be 95% then surely a 4.2kWp DC panel capacity would produce a net 3.99kWp system and therefore be open to the higher rate FIT of 41.3p/kWh .... ???????

Could someone clarify ....

Regards
Zeupater

Doc_N

I'm still waiting for a Tesco quote after contacting them around 6 weeks ago. The Mark Group (who do the surveys) have been slow, as they have been with an e.on quotation, and they compare very unfavourably with the speed and efficiency of a local MCS installer.

e.on were quite a lot more expensive than the local firm, but if the prices on their website are anything to go by, Tesco will be somewhat cheaper. They've been pretty rubbish so far, though - unable to speed up the quotation process and unable to give any detail at all as to the components they use.

IF they're using Sharp or Mitsubishi panels, and an SMA inverter, they could be an option, though my guess is they'll be paying the contractor such a low price that he might not have sufficient incentive to do a really neat job - and I don't want the appearance of my house messed up, inside or out.

If they're using inferior components to keep the price down (which could be the case) they're best avoided. I'll also be interested to see how far adrift from the 'guideline' prices they are - I'm guessing, but I bet there'll be some good reason why my house is somehow 'different' and will cost more!

Cardew

zeupater wrote: »

Hi

Read it, very interesting and has changed slightly since I last looked ..

One question arises though ... the claim that the system size is (kWp) is based on the output of the panels x the number of panels and that the 4.2 kWp system is 24 panels (ie 175W) therefore the FIT, being over the 4kWp threshold, reduces one band to 36.1p/kWh produced .....

I have it at the back of my mind that the FIT threshold is based on a net export AC production not the gross DC nominal capacity, therefore the efficiency of the GTI and the entire system should be included. If the nominal efficiency of the GTI was to be 95% then surely a 4.2kWp DC panel capacity would produce a net 3.99kWp system and therefore be open to the higher rate FIT of 41.3p/kWh .... ???????

Could someone clarify ....

Regards
Zeupater

Good question!

I suspect that as the kWp figure for panels is notional - produced under specific lab conditions(irradiance/temp/pressure etc) - and unlikely to be reached in UK, the panel size in kWp is the sole criteria used.

If you introduced a variable - length of cables, efficiency of inverter etc to downgrade the output, where do you stop?

Lattitude in UK? aspect of roof? etc

noncom_2

I've tried asking this on the Navitron forum, but so far nobody's replied...... so I'll see if there are any experts here who can advise me quicker!

I had three quotes from PV installers the other day, and there was one fundamental disagreement between them. We have two roofspaces on the back of the house, either or both of which could be used. They both face in exactly the same direction (210deg, so just slightly West of directly South), but the roof on the extension at the back is lower (single storey) and a shallower pitch. So we have a rectangular extension roof at about 30 degree from horizontal pitch, and an irregular shaped main roof above with a more traditional pitch of perhaps 45-50 degrees.

There are no significant shading issues on either roofspace if we site the panels carefully.

Ideally I'd like to get a system as close to 4kW as possible to maximise the return-cost ratio with the FITs, but neither of the two spaces on their own is big enough to do this (probably get about 3kW on the top one if we used the most efficient panels).

However two of the three installers recommended putting panels on both spaces, linked to a single inverter (wired as a single series string). The third said that because the pitches of the roofs are different, then the fact that the blocks of panels will always operate at different efficiencies from each other (due to the different angles to the sun wherever it is), will act as a brake on the whole system, and we'd be better off simply putting a single block onto the larger roof and ignoring the lower one entirely. They weren't trying to sell me an extra inverter, so I don't think it was anything other than a genuine opinion, but I wondered what people here (installers preferably) thought about this? Is the difference in the two pitches really significant enough to make using both areas together (with one inverter) a bad idea?

Hoping someone can help me make a decision.....

zeupater

Cardew wrote: »

Good question!

I suspect that as the kWp figure for panels is notional - produced under specific lab conditions(irradiance/temp/pressure etc) - and unlikely to be reached in UK, the panel size in kWp is the sole criteria used.

If you introduced a variable - length of cables, efficiency of inverter etc to downgrade the output, where do you stop?

Lattitude in UK? aspect of roof? etc

Hi

I've just spent a couple of hours looking through every source I could find on this and every reference seems to be 'capacity', but I've yet to find the definition of 'capacity'. I agree with the point raised about the individual installation variables but would have thought that the nominal capacity of the installation would be the resultant of (nominal panel capacity) x (nominal inverter efficiency) which would tie up with grid tied restrictions .... well doesn't that say it all for government joined up thinking if it is 'panel only' based ..... :rotfl:

Whichever is correct is only really an interesting and academic point for myself as I'm not looking at a 4.2kWp installation, sizing the system to the panel capacity would work just as well for me

Regards
Z

Cardew

zeupater wrote: »

Hi

I've just spent a couple of hours looking through every source I could find on this and every reference seems to be 'capacity', but I've yet to find the definition of 'capacity'. I agree with the point raised about the individual installation variables but would have thought that the nominal capacity of the installation would be the resultant of (nominal panel capacity) x (nominal inverter efficiency) which would tie up with grid tied restrictions .... well doesn't that say it all for government joined up thinking if it is 'panel only' based ..... :rotfl:

Whichever is correct is only really an interesting and academic point for myself as I'm not looking at a 4.2kWp installation, sizing the system to the panel capacity would work just as well for me

Regards
Z

I understand the point that you are making, however does it matter if they took your definition and made it, say, 4.5kWp in panel output to allow for losses? 4kWp is just an arbitary figure.

Perhaps it would have been fairer to have set a limit on the maximum output in kWh that would attract FITs.

So if someone generated 4,300kWh they would only get FIT on 4,000kWh.

At the moment someone in North Scotland cannot get the same level of subsidy(FIT) as someone in South West England as a 4kWp array in Northern latitudes will produce considerably less output than an array in Southern England.

zeupater

Cardew wrote: »

I understand the point that you are making, however does it matter if they took your definition and made it, say, 4.5kWp in panel output to allow for losses? 4kWp is just an arbitary figure.

Perhaps it would have been fairer to have set a limit on the maximum output in kWh that would attract FITs.

So if someone generated 4,300kWh they would only get FIT on 4,000kWh.

At the moment someone in North Scotland cannot get the same level of subsidy(FIT) as someone in South West England as a 4kWp array in Northern latitudes will produce considerably less output than an array in Southern England.

Hi

Understand & agree, there needs to be a simple system which is easy to administer as we all know how unnecessary complexity only causes confusion.

I thought that the 4kWp threshold was not quite as arbitary as it first seems, with the figure being based on what could be readily accepted to the grid per phase for households across the country without requiring specific checks for each installation.

As for the balance on arrays in more northerly latitudes not producing the same output as ones further south, isn't this the total kWh production which is related to the number of daylight hours and solar incidence, therefore if looking at kWp isn't it the case that an array, if installed at the appropriate angle, is capable of reaching approximately the same peak production in either location, although it is more likely to maintain higher outputs for longer periods further south ?

I don't know how sound these points are as they're based on what I've recently picked up and am only really starting to understand pv technology prior to installation, but would have thought that both would be the case from a logical point of view, so would appreciate your views.

Thanks
Z

Cardew

zeupater wrote: »

Hi

Understand & agree, there needs to be a simple system which is easy to administer as we all know how unnecessary complexity only causes confusion.

I thought that the 4kWp threshold was not quite as arbitary as it first seems, with the figure being based on what could be readily accepted to the grid per phase for households across the country without requiring specific checks for each installation.

As for the balance on arrays in more northerly latitudes not producing the same output as ones further south, isn't this the total kWh production which is related to the number of daylight hours and solar incidence, therefore if looking at kWp isn't it the case that an array, if installed at the appropriate angle, is capable of reaching approximately the same peak production in either location, although it is more likely to maintain higher outputs for longer periods further south ?

I don't know how sound these points are as they're based on what I've recently picked up and am only really starting to understand pv technology prior to installation, but would have thought that both would be the case from a logical point of view, so would appreciate your views.

Thanks
Z

The irradiance is way higher in the South hence highr output

There are many maps like this which give solar output based on geographic location.

http://re.jrc.ec.europa.eu/pvgis/download/PVGIS-EuropeSolarPotential.pdf

You can see there is a large difference between NW Scotland and SW England. around 30%.

Taking two extremes the output from a 1kWp panel in Southern Spain is over 500% more than Northern Europe.

John_Pierpoint

noncom wrote: »

I've tried asking this on the Navitron forum, but so far nobody's replied...... so I'll see if there are any experts here who can advise me quicker!

I had three quotes from PV installers the other day, and there was one fundamental disagreement between them. We have two roofspaces on the back of the house, either or both of which could be used. They both face in exactly the same direction (210deg, so just slightly West of directly South), but the roof on the extension at the back is lower (single storey) and a shallower pitch. So we have a rectangular extension roof at about 30 degree from horizontal pitch, and an irregular shaped main roof above with a more traditional pitch of perhaps 45-50 degrees.

There are no significant shading issues on either roofspace if we site the panels carefully.

Ideally I'd like to get a system as close to 4kW as possible to maximise the return-cost ratio with the FITs, but neither of the two spaces on their own is big enough to do this (probably get about 3kW on the top one if we used the most efficient panels).

However two of the three installers recommended putting panels on both spaces, linked to a single inverter (wired as a single series string). The third said that because the pitches of the roofs are different, then the fact that the blocks of panels will always operate at different efficiencies from each other (due to the different angles to the sun wherever it is), will act as a brake on the whole system, and we'd be better off simply putting a single block onto the larger roof and ignoring the lower one entirely. They weren't trying to sell me an extra inverter, so I don't think it was anything other than a genuine opinion, but I wondered what people here (installers preferably) thought about this? Is the difference in the two pitches really significant enough to make using both areas together (with one inverter) a bad idea?

Hoping someone can help me make a decision.....

If you get a reasoned reply please let us know - I have a potentially similar quandary.
I would really like to know how the installers fixed and variable costs break down:
ie Marginal direct costings:
A. £ xxx Hassle in the office doing desk check that the potential customer is not a nutter, lives within reasonable distance, has a property that looks possible (see Google/MSN street-view/satellite. Planning restrictions. Ownership. Trees?.
B. £ xxx Cost of survey (half a day? third of a day?) Allow for excuses and whistling through teeth and time wasters; looks like she/he would rather have a divorce than spend money on roof panels. Bear in mind the likely hit rate, given at least 2 competitors, of say one in 6 surveys? Is this survey just going to be used to push down the price of the installer already chosen?
C. £xxx Drawing up quote (can this be done on the spot using a lap top for simple installations?). Checking back at the office for snags found on the visit. Can the customer finance the deal? Are thete local authority or covenant problems?
D. £xxx cost of 3 - 4 Kw's of panels, with attendant electrical controls and wiring.
E. £xxx cost of DIY or contractor's scaffolding, serious if not a bungalow - see working a height regs.
F. £xxx Checking out potential hassle with electricity supplier and possible/probable need to update elements of customer's obsolescent wiring.
G. Send quote get deposit.
F £xxx Time on site with one/two big vans (3 man days??)
G. £xxx Potential hassle when customer tries to sign up with electricity supply company.
H. Collect balance of contracted amount.

Grand total in time and money for a typical installation.........

Overheads: x% to absorb annual costs such as rent, rates, accounting, legal services, training, buying etc etc.

Expected profit £xxx
Elapsed time in weeks

Perhaps someone in the trade could correct my off the cuff posting & give us some pointers to life in the real world (we would be better customers if you can educate us before the survey visit!!)
craftymummy are you still reading this?

The cynic in me thinks that the company who only want to panel the (hip end?) top roof are working on a model of hassle free installation of 3KW for everyone. They cannot see how to make a profit out of the extra work and hassle of doing the lower (shaded?) roof. Lets get on an do another customer, while the gold rush lasts.

While the guys prepared to do both roofs (isn't 30 degrees the "ideal" slope?) are working on "the customer is always right". If that is what he wants, that is what he will get. The marginal extra costs means mostly money in the bank.