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Solar PV Ordered!

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After seeing my electric bill motor from £60 per month two years ago to £150 last month I decided to take the plunge.

We are having a 3.8KW system, can't fit any larger on the roof.

Hopefully this should provide a significant proportion of our demand. The installer has calculated a return of £2k per year index linked for the next 25 years.
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Comments

  • :)We've got a 3.33kWp system.18 Mitsubishi panels, Diehl 3800S inverter, due south & unshaded S.Powys location.
    The installers system figures were pessimistic, with an estimated 2216kWh annual yield. The solarguide.co.uk calculator suggests 2904kWh. Our previous annual usage was 3133kWh, or 8.6kWh/day.
    In practice, our 8.5days since commissioning have generated 96kWh, or roughly 11.3kWh/day.
    This has been an unsettled week, unlike the weeks of wall to wall sunshine that preceded it. Despite one completely overcast day which generated only 5kWh, many days were in double figures with a maximum of 16kWh generated last Saturday.
    Its early days yet but we are well on track to match or exceed the Solarguide April estimate of 331kWh and annual generation to reach our 3133kWh usage. We've not received our MCS certificate yet and so FIT payments are a long way off. :)
  • keith_r59
    keith_r59 Posts: 255 Forumite
    The sunshine recorded for March was well above average this year and my own installation generated 40% more kWh than expected. Let's hope it continues for the rest of the year.

    http://www.metoffice.gov.uk/climate/uk/anomacts/
  • noncom_2
    noncom_2 Posts: 212 Forumite
    stoozey wrote: »
    Hopefully this should provide a significant proportion of our demand. The installer has calculated a return of £2k per year index linked for the next 25 years.

    That seems HIGHLY optimistic. Did they give you the figures on which they based that estimate??

    We have a 3.96kW system, and the predicted return is nearer £1500pa. So far, November to Feb performed worse than predicted, March was better (all in line with the somewhat unusual weather patterns over those months).

    Of course, it all depends on where you live (if you're right on the South Coast and absolutely bang on South-facing your figures will be a little better than ours) and what your patterns of electricity usage are (ie how much of the energy you use is during the daytime when the panels will be generating).

    Still be surprised if you see close to £2k though, I'm afraid.
  • thenudeone
    thenudeone Posts: 4,462 Forumite
    Part of the Furniture 1,000 Posts Combo Breaker
    noncom wrote: »
    That seems HIGHLY optimistic. Did they give you the figures on which they based that estimate??

    I would agree. I've had quotes for a number of near-4kW systems and £1400 seems to be the average saving quoted. You might get a bit more if you are the far south of England, but not that much more.
    We need the earth for food, water, and shelter.
    The earth needs us for nothing.
    The earth does not belong to us.
    We belong to the Earth
  • Cardew
    Cardew Posts: 29,059 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Rampant Recycler
    stoozey wrote: »
    Hopefully this should provide a significant proportion of our demand. The installer has calculated a return of £2k per year index linked for the next 25 years.

    In the Midlands I would expect your estimated output from a 3.8kWp system to be around 3,200kWh a year.

    That gives an income fro FIT and selling back of approx £1,425 then perhaps £100 off your electricity bill, so the £2k seems about £500 too high.
  • Cardew
    Cardew Posts: 29,059 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Rampant Recycler
    Pryderi wrote: »
    :)We've got a 3.33kWp system.18 Mitsubishi panels, Diehl 3800S inverter, due south & unshaded S.Powys location.
    The installers system figures were pessimistic, with an estimated 2216kWh annual yield. The solarguide.co.uk calculator suggests 2904kWh. Our previous annual usage was 3133kWh, or 8.6kWh/day.
    In practice, our 8.5days since commissioning have generated 96kWh, or roughly 11.3kWh/day.
    This has been an unsettled week, unlike the weeks of wall to wall sunshine that preceded it. Despite one completely overcast day which generated only 5kWh, many days were in double figures with a maximum of 16kWh generated last Saturday.
    Its early days yet but we are well on track to match or exceed the Solarguide April estimate of 331kWh and annual generation to reach our 3133kWh usage. We've not received our MCS certificate yet and so FIT payments are a long way off. :)

    Welcome to the forum.

    Your previous consumption(annual usage) of 3,133kWh has no bearing on how much your panels will generate; so not sure of the relevance of being 'on track' to reach that usage.

    From a 3.33kWp sytem in South Powys, the solarguide estimate of 2,904kWh pa.seems perfectly reasonable. However that would presumably be under perfect conditions - i.e. correct pitch and orientation without any shading early morning/late evening.

    It is very surprising that the installers would estimate 2,216kWh pa unless the siting was less than optimum.
  • pmpm
    pmpm Posts: 26 Forumite
    stoozey wrote: »
    After seeing my electric bill motor from £60 per month two years ago to £150 last month I decided to take the plunge.

    We are having a 3.8KW system, can't fit any larger on the roof.

    Hopefully this should provide a significant proportion of our demand. The installer has calculated a return of £2k per year index linked for the next 25 years.

    how much you are paying for it if you don't mind me asking
  • I can see exactly why they underquote, since they are my energy supplier, they do not want me coming back to them demanding compensation for any underperformance.
    The roof faces very nearly due south [177degrees] and is unshaded.
    System cost was £13.8.
    Today was our first day with blue sky & sunshine throughout. 18 kWh generated.
    We do have local favourable met conditions as on windy days the mountain ridges to the south and north of us will generate standing wave clouds with a fixed blue gap over our village. Tuesday the 5th was a classic day with strong S Westerlies, unbroken cloud over much of Wales but 14kWh of generation here. :)
  • zeupater
    zeupater Posts: 5,389 Forumite
    Part of the Furniture 1,000 Posts Name Dropper Combo Breaker
    Pryderi wrote: »
    I can see exactly why they underquote, since they are my energy supplier, they do not want me coming back to them demanding compensation for any underperformance.
    The roof faces very nearly due south [177degrees] and is unshaded.
    System cost was £13.8.
    Today was our first day with blue sky & sunshine throughout. 18 kWh generated.
    We do have local favourable met conditions as on windy days the mountain ridges to the south and north of us will generate standing wave clouds with a fixed blue gap over our village. Tuesday the 5th was a classic day with strong S Westerlies, unbroken cloud over much of Wales but 14kWh of generation here. :)
    Hi Pryderi

    You might find that the installer has allowed for some shading to compensate for the hills/mountains in the calculation. If you're in a valley, the change in the horizon can reduce the direct sunlight hours and therefore effect your production capacity, however, the SAP calculation is based on a countrywide averaged insolation and therefore will not take your local conditions into consideration.

    I would suggest that you have a look at the PVGIS site (http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php) to calculate more accurate generation figures for your location. You will need to select the 'CLIMATE-SAF PVGIS' database as this will likely be a far more accurate dataset for where you are, also select the 'Show Graphs' & 'Show Horizon' options. The system will produce a monthly generation prediction for your exact location which you will be able to use to track your system performance.

    Happy Generating, and welcome to the forum .... :)

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • jerryd
    jerryd Posts: 24 Forumite
    Part of the Furniture Combo Breaker
    Just had my system installed as well. Paid £12k for a 3.92 kW system which was installed in a single day last Wednesday. First week has been a bit cloudy but it looks like I'll be back on target after a very sunny day today. Too early to say if the system will match my expectations however initial impressions are very good.

    I applied for and got Building Regulation approval for my system. My council said I had to although some seem to take a more relaxed approach. I have a USB stick collecting data from my inverter which I'll publish on my blog at the end of the month.
    I'm working on it !
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