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Home energy

Discussion in 'Serious' started by GMC, 15 Jun 2015.

  1. GMC

    GMC Well-Known Member

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    Thanks for the note and the vid!

    I need to get a calculator, but looks like you generate an average of about 0.5 kwh per hour in use, which is presumably the time since installed - about 1.5 years in your case , with a 2kwh system

    Is scaling linear? i.e. roofspace notwithstanding would a system twice the size of yours generate twice the power on average? that would generate an average (over time) of 1 kwh per hour so about 12 kwh per day. That seems pretty substantial compared to the usage figures being given by people on the thread.

    No tinfoil here, or desire to go full hippy. Just fed up of permanently rising costs from energy companies who seem to do very little about transitioning to a more sustainable model (cost or environmental) and the Tesla announcement seemed like a potential alternative.
    Basically I want to see how close to self sufficient you can get by doing as as Harlequin has done, but rather than sell back excess midday supply, timeshift it by storing and use that during peak evening demand before buying from the grid if/when the surplus is drained.

    I live in a 4 bedroom detached bungalow so have a fair bit of surface area on my roof.
     
  2. Guinevere

    Guinevere Mega Mom

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  3. Xir

    Xir Well-Known Member

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    And the existing Sunpac from Solarworld
     
  4. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    Sorry, but this response is somewhat niaive, unqualified and factually incorrect.
    I live in Liverpool, UK and we've had solar panels fitted, along with a feed in metre and inverter.

    In MArch we had 14x0.5kw solar panels installed on our roof, which after a somewhat arduous install process came online some 6-7 weeks ago.
    At the last check (last weekend) these have generated a little over 1000 units of electricity, which we are TRYING to consume entirely, but inevitably can't, "wasting" the surplus -

    Since installation, the leccy billy has reduced from £117 per month to £57 (using British Gas' current rates) based on an average consumption compared to the average taken over the past 2.5 years, our payments have been fixed and amortised at £117 to cover the increased use in winter, and lower use in summer. We use a fair bit of leccy, especially considering we have gas central heating, but that's a different conversation.

    If we had batteries to store the excess which we currently waste, we WOULD further reduce our consumption to an almost trivial amount - it cannot be zero for our particular install as the inverter, which converts our DC to AC, requires a mains power feed.
     
  5. asura

    asura jack of all trades

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    A colleague recently finished a house with (as I recall) 12 panels, it is pretty much the standard to meet in terms of insulation levels and air tightness, it has a MHVR system, underfloor heating, wood burning stove and etcetera. It doesn't use an air source heat pump, and it does have an electric oven and hobs. The predictions from the SAP calculations gave an estimated annual bill of £300-ish.

    I caught up with him over a glass of wine a couple of days ago now, you having spurned my curiosity and reminded me about it... the first year electricity bill is approximately -£250*, and the wood burning stove isn't commissioned yet, once that's in it'll probably "fall" even further.

    *yes, it's earning a profit - not much of a one obviously, but if you compare it to the average electricity + oil/gas bills locally, it's a staggering amount!
     
  6. Harlequin

    Harlequin Well-Known Member

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    btw EON have just reduced my direct debit from 84 to 64 a month - using the tumble dryer on low doesn't cost me as its using whats coming off the roof

    Tatty - is your feed in tarrif sorted to sell your excess back to the grid?
     
  7. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    Not as far as I can tell mate - we are on the FiT scheme but I don't believe that we're physically EXPORTING any leccy, back to the grid.

    I'll clarify that statement - when the Solar panels and Inverter were fitted, we had an L&G E110 "production" meter installed - this sits next to the std "Grid-consumption" meter -
    The L&G unit just reports what has been generated and I don;t believe that it is physically wired up to export anything outside the house, hence my desire to store the surplus of what's produced...

    Taken from the British Gas Feed in Tariff summary:
    #..snip
    Installation Type: Solar PV
    Export payments (Select Opt in / Opt Out): Opted In
    Export Status: Unmetered
    Grid Connection Status: Connected to Grid
    ..snip#

    As for the tariff, these are the details:
    #..snip
    Eligibility Date(Date of eligible installation): 11/05/2015
    Eligibility Period: 20 Years
    Generation Tariff as at Confirmation date: 13.39p kwh
    Export Tariff as at Confirmation date: 4.85p kwh
    ..snip#

    Unless I'm mistaken and then in which case we would get 4.85p per KWH that we export back to the grid as well as 13.39p for producing it...?
     
  8. Harlequin

    Harlequin Well-Known Member

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    yes - when your not using whats coming off the roof it flows `back` through your standard meter

    and you should be able to get feed in tariff payments (as long as your installer is certified) and you bought the system ofc and its not rent a roof., and your registered with a company. IIRC they pay quarterly
     
  9. RTT

    RTT #parp

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    Actually all I have is a macbook air which when on charge consumes a whopping great 45W (max) :D
     
  10. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    I believe that this is exactly what we signed up for. Wasn't aware that the surplus went out though...

    Not sure how you'd measure a surplus even....
     
  11. Harlequin

    Harlequin Well-Known Member

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  12. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    Ta +rep :)

    The section:
    Export tariff (E) is payable on the units of electricity you export back to the national grid because you haven't used them in your own property. In the case of most small-scale technologies - or unless you already have a two-way smart meter installed - the level of electricity exported is currently 'deemed' by assuming you export 50% of the electricity you generate.

    was of particular interest :)

    So we'll get paid 13.39p for every unit that we generate, then for half the units that we generate we'll get paid an export tariff of 4.85p

    So, on 1000 units we'll get paid:
    1000 X 0.1339 =133.90 +
    500 X 0.0485 = 24.25
    =£158.15

    Not bad for 6 weeks!

    Also, during that same 6 week period our measured electricity consumption has dropped by £70 (based on £50 per month reduction in payments)

    making a net earning of £228 vs a bill of:

    Loan: £98
    Revised Electricity bill: £57
    Total outgoings: £155

    This leaves a surplus of £228-£155 = £73

    so we could legitimately afford to pay an additional £73 per month in the summer based on the bill we WERE paying in order to pay off the loan sooner. I'm just going to put everything we earn off the roof off the loan as we get it in.
    The sooner that's paid off, the sooner it'll be paying us - the net monthly outgoing increase of £50 (bill was -£50, but loan = +£98 so net of +£48 to our monthly outgoings) is enough to be able to swallow at the moment - that might well change once I get the cheque though...

    Wonder if you pay tax on that as it is an income...?
     
  13. Harlequin

    Harlequin Well-Known Member

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    https://customerservices.npower.com...ave-to-pay-tax-on-my-feed-in-tariff-earnings?

    nope , no tax payable

    edit:

    from reading

    http://www.which.co.uk/energy/creat...xplained/feed-in-tariff-savings-and-earnings/

    I think you`ve exaggerated your income figures ; as your not generating 24 hours a day :D

    for me using

    http://www.solarguide.co.uk/solar-pv-calculator#bestresult

    Investment in 2.00kWp System: * £ 3,729.06
    First Year: Income from Feed-In Generation Tariff @ 13.39p/kWh: £ 236.92
    Income from exporting energy @ 4.85p/kWh: £ 42.91
    Electricity Saving: £ 119.61
    Total Benefit: £ 399.43
    Payback Time: 8y 3m
    Total Profit Over 20 years: £ 7,909.65
    10.61 % per year (5.69% AER)
     
    Last edited: 22 Jun 2015
  14. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    I'll get back to you on 3rd August when the first cheque payment is due, but I'm going off metered readings so I can't see how they're exaggerated - I agree that they seem high though, especially when I customise the site to reflect my deets, it shows an ANNUAL income of £440.

    The only thing I can thing of is that each unit on our metre is not the same as a kWH...?

    Our first payment is due 3rd August - we'll see then.... :)
     
  15. badders

    badders Neuken in de Keuken

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    Hmmm, we've had a bloke round this evening, and quoted us £8495 for a 14-panel 3.92KWp system with a string inverter, or £10Kish for the same but with Microinverters. This included bits to feed what we're not using into the immersion heater, negating the need for the boiler to come on to keep our hot water hot, and some smart hot water/heating controller.

    I didn't sign on the dotted line - he was only a single data point, but is this expensive? Middle of the road?
     
  16. Jumeira_Johnny

    Jumeira_Johnny 16032 - High plains drifter

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    No, it's not. There is a huge difference between grid tie-in and off grid when it comes to people who design them to continue living a normal life.

    Off grid needs to have an overhead. Using a few panels in a grid tie in system to compare to the OP's plan to move off grid is what is naive.

    I fully support a grid tie in system. As I stated before: Germany has shown us what a large scale tied in system of local PV production can accomplish in northern Europe. But it's not off grid. Having looked at off grid with the normal lifestyle of a 2 person, non hippy, household in their 40s.......

    Well, good luck.
     
  17. Jumeira_Johnny

    Jumeira_Johnny 16032 - High plains drifter

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    lame. I had fantasies of a hot tub plumbed to a liquid cooled server farm.
     
  18. Harlequin

    Harlequin Well-Known Member

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    high end of pricing - in fact reading on MSE , its about £1500 above the high end

    you should be able to locate a system for between 5k and 7k now for 4kwh

    apparently 8.33 gallium panels are amoungst the best - with an ABB invertor.
     
  19. Almightyrastus

    Almightyrastus Rule #9

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    We do make some nifty stuff :thumb:

    (disclaimer - I don't have anything to do with inverters, i'm on the lightning and surge protection side of things)
     
  20. Tattysnuc

    Tattysnuc Thinking about which mod to do 1st.

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    OK - as promised a follow up.
    I've just supplied our meter reading after 90 days - it was 1960 units. The start reading was 720 so therefore we have generated 1240 units.

    A quick bit of maths:

    1240 X 0.1339 = £166.036 +
    620 X 0.0485 = £30.07
    = £196.106

    Now, I know that the amount of sunlight changes over the year and that this represents the richest period, but I'm sure that this is more than the £427 that SolarGuide predicts we will generate, I'd put it nearer £500-£550 income per year and saving £70 per month vs consumption.

    I'll just need to make sure that I don't spend the pennies before I've got them :)

    I'll update as more readings come in. If only we could store more of the electricity during the day rather than exporting it, then we wouldn't be far off being "off the grid" - financially at least....


     

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