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  1.  
    With solar subsidies being cut from January 2016, I was wondering what impact this would have on domestic installations. Traditionally it seemed that most people were installing 4kw systems and that it was anticipated that most households would use 50% of this, hence the 50% export part of the FIT payments. However, I read that most people don't use even 50% of their generated solar?

    If subsidies are withdrawn, do people think that domestic installations will be sized to individual use to reduce installation costs and increase payback periods rather than utilising all of the available roof space as happens at the moment?
  2.  
    Unless I have missed a later announcement, note that if the gov't proposal goes through, for at least for a while the export tariff will be about 3x the generation tariff.
    • CommentAuthorringi
    • CommentTimeDec 1st 2015
     
    Domestic installations will no longer give a return on investment until the costs decrease, unless other roofing work is being done at the same time.
    • CommentAuthorgravelld
    • CommentTimeDec 1st 2015
     
    Yeah, the 50% usage mark was very high. Unless you are running an immersion diverter you're unlikely to achieve that.

    I don't really see the point of sizing to use - it's a similar situation to insulation. The panels aren't really the expensive bit...
  3.  
    I did wonder about that. I guess the expensive part is labour and while it might be quicker to fit a 1kw or 2kw rather than 4kw, the installer would probably still charge a daily rate. The scaffolding costs would be the same for both and the inverter wouldnt be hugely cheaper for 1kw or 2kw rather than 4kw either.

    The only real difference with a smaller sized system would be that the roof would have free space, maybe for a solar thermal panel? Though I guess a PV diverter such as immersun would do this anyway?
    • CommentAuthortony
    • CommentTimeDec 1st 2015
     
    Now end Feb 2016 for the change
  4.  
    Posted By: gravelld
    I don't really see the point of sizing to use - it's a similar situation to insulation. The panels aren't really the expensive bit...

    Plus, which month to base such sizing on? Mean generation in June/July can easily be 5 or more times December/January (up here with our WSW facing array the factor is more like 10).
    • CommentAuthorringi
    • CommentTimeDec 1st 2015
     
    Battery systems are also coming down in price so in say 5 years time you may want all the 4kw for charging.
  5.  
    I'm currently installing a 4kW system split east / west. Being out at work all day I don't think I'll actually use much of what I generate (except at weekends). I'm hoping that when batteries become viable in the domestic setting that will be the real game changer.
    • CommentAuthorowlman
    • CommentTimeDec 1st 2015 edited
     
    <blockquote><cite>Posted By: Pile-o-Stone</cite>With solar subsidies being cut from January 2016,

    Are you sure?? Last I heard via the Solar industry was that it's likely it'll be put back till late February and quite possibly later, at the earliest. It doesn't affect the rest of what you said.

    Sorry tony is that what you meant, just noticed your post.
    • CommentAuthorbxman
    • CommentTimeDec 1st 2015
     
    Well let us hope common sense will prevail and the drastic reduction does not occur .

    As a species we need all the carbon free energy we can get.

    The hardware costs should continue to decline but the regulatory and installation costs are not going to reduce.

    The population with an interest in the technology have in general have already had PV installed and likewise the better sites have been utilized so installations were going to decrease naturally

    it was planned that the feed in rates were going to decline in any event .And more importantly we need Power to Gas and Pumped Storage to be able to make best use of it .

    It had taken 5 years for the DNO's to at last accept larger systems could be capped to the 16amp export without the exorbitant cost of an EMMA .

    Even a 4kw system is not going to give a very good supply during the dark days of November and December

    I think the Government got it completely wrong.

    I just pray they have got the balls to admit they made a mistake.
    • CommentAuthorringi
    • CommentTimeDec 1st 2015
     
    Personally I think if we had invested the money in CHP boiler systems instead of PV as a nation we would be in a better state. PV does not give the output at the times of day/year that we most need it in the UK.

    Wind should have been push a lot more, including sorting out the planning system. It can cost as much in planning and sites that are not allowed to be developed as the hardware itself.

    And what about wave power – I don’t understand why it has not come on a lot more.

    Tidal power should also be big for us, but is not yet, - why?
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 1st 2015
     
    Was a different government that 'got it wrong', and that one is still unable to admit that they got other things wrong.

    Module prices are now pretty flat:
    http://www.pv-magazine.com/investors/module-price-index/

    I was at a place that does battery systems today. Not sold on them yet at all. How long have we been hearing that they are going to be a game changer, 5 years, 10 years, 20 years.
    You would still need a lot of space to fit them as well.
    •  
      CommentAuthorfostertom
    • CommentTimeDec 2nd 2015
     
    Posted By: bxmanthe better sites have been utilized
    I doubt that - there's no end of optimum sites still to come.
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 2nd 2015 edited
     
    Posted By: ringiAnd what about wave power – I don’t understand why it has not come on a lot more.
    I do. Have you ever seen a 7 tonne block of granite being pushed up the street by a wave, after that same wave has turned into an inlet, travelled 200 m, smashed into some rocks, jumped over a 2 m wall and still managed to move the block 20 m.
    That one wave probably only had 20% of the energy that it had 5 minutes earlier.


    Posted By: ringiTidal power should also be big for us, but is not yet, - why?
    It is the environmentalists/conservationists, they have a very narrow view of the world, but are a powerful lobby.


    Posted By: ringiWind should have been push a lot more, including sorting out the planning system. It can cost as much in planning and sites that are not allowed to be developed as the hardware itself.
    Yes, trouble is that planners and the general public just don't don't understand how they work. They have it in their minds that big is bad, but allow a clutter of small ones close together.
    Between St. Erth and Marazion, only about 3 miles, there is 6 or 7 sub 50 kW turbines scattered about. The farmers should have just got together and plonked 1 200 kW turbine in, it would have been cheaper, produced more and been less visual than the scattering they now have.
    Better still, they could have put in just one 2 MW one and given the local area some really useful power.
  6.  
    The question I've never seen a satisfactory answer to is what is the market value of domestic PV generation? We see figures for the average wholesale price of electricity but how can this be compared with domestic PV? On the one hand its output is always when demand is relatively high (during daylight hours) and never when it is at at its lowest (early hours of the morning). On the other it can't be ramped up or down on demand. And how does one compare electricity that is fed into the grid at about 230V "ready to use" with centralised generation that needs transforming and transmitting longer distances? Is the PV electricity more valuable because of this?

    Without knowing that, surely one can't even say by how much domestic PV is/should/could be subsidised or make meaningful comparisons with other forms of low carbon electricity.
    • CommentAuthoratomicbisf
    • CommentTimeDec 2nd 2015 edited
     
    Posted By: ringiPersonally I think if we had invested the money in CHP boiler systems instead of PV as a nation we would be in a better state. PV does not give the output at the times of day/year that we most need it in the UK.

    Wind should have been push a lot more, including sorting out the planning system. It can cost as much in planning and sites that are not allowed to be developed as the hardware itself.

    And what about wave power – I don’t understand why it has not come on a lot more.

    Tidal power should also be big for us, but is not yet, - why?


    I'm doubtful of CHP - reviews seem to suggest that unless your heat demand is unusually high, the amount of electricity you get is rather small. Besides, I think it's now too late in the day to be pushing another fossil-fuel technology, even one that is less bad than the one it replaces. Much like replacing coal with gas, it's an improvement, but unless the gas is then replaced with something better again much sooner than is commercially acceptable after spending all that money on the gas infrastructure, we won't make the GHG cuts we need in time. By encouraging a new fossil fuel technology you're either saying "invest in this (but by the way you'll have to scrap it all well before its economic life is up)" or "invest in this (we're not really serious about the GHG commitments we've made - do you really think we'll make you scrap it well before its economic life is over?)

    Wind is a good plan, it just needs a more robust approach to the vocal minority opposing it which would be fully democratic given that a large majority favour its expansion.

    I like the idea of tidal but I'm not so sure of the economics. It uses large scale, pretty mature engineering that seems unlikely to come down a great deal in price unlike say solar or wind.

    Ed
    •  
      CommentAuthorfostertom
    • CommentTimeDec 2nd 2015
     
    Posted By: SteamyTeaHave you ever seen a 7 tonne block of granite being pushed up the street by a wave, after that same wave has turned into an inlet, travelled 200 m, smashed into some rocks, jumped over a 2 m wall and still managed to move the block 20 m.
    That one wave probably only had 20% of the energy that it had 5 minutes earlier.
    But that's a breaking wave, expending all its energy by head-on collision. Wave power isn't on the shore (is it?) - is out at sea and just uses the rise and fall (or 'bending' of the surface) of passing waves - no impact.
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 2nd 2015
     
    The market value of domestic PV is what it currently is.
    What you want to know is what is the free market value. This is harder to answer and you have to take all the costs into account.
    So you have to put a price all the external cost of all the other generation types as well to get a true price.
    One way to do this is to put a price on the cost of emitting CO2e. This is a global cost i.e. is lost farm production in Bangladesh worth the same as in the Mid West USA. I would say it is, but other would say not.

    That is partly why you have not had an answer to that question.
    • CommentAuthoratomicbisf
    • CommentTimeDec 2nd 2015 edited
     
    Posted By: SteamyTeaThe market value of domestic PV is what it currently is.
    What you want to know is what is the free market value. This is harder to answer and you have to take all the costs into account.
    So you have to put a price all the external cost of all the other generation types as well to get a true price.
    One way to do this is to put a price on the cost of emitting CO2e. This is a global cost i.e. is lost farm production in Bangladesh worth the same as in the Mid West USA. I would say it is, but other would say not.

    That is partly why you have not had an answer to that question.


    Posted By: SteamyTeaThe market value of domestic PV is what it currently is.
    What you want to know is what is the free market value. This is harder to answer and you have to take all the costs into account.
    So you have to put a price all the external cost of all the other generation types as well to get a true price.
    One way to do this is to put a price on the cost of emitting CO2e. This is a global cost i.e. is lost farm production in Bangladesh worth the same as in the Mid West USA. I would say it is, but other would say not.

    That is partly why you have not had an answer to that question.


    That's not really the question whose answer I was looking for. Accounting for all the external costs is a good idea, but not one that is often used. What I'm looking for is the unsubsidised price of solar PV so as to better make a comparison with other technologies and other sources of electricity.

    Ie if I install 4 kW of solar PV on my roof and export say 3000 kWh per year, what would be the unsubsidised price of the electricity I sell? Is the 5p/kWh or so export tariff an unsubsidised price? Or would I be subsidising the electricity companies because they can then sell it directly to my neighbours for 10-15p without having done any extra work?

    Or in other words what is the actual subsidy, once one removes the "true" value of the electricity.

    Or... if we want to try and and compare with the proposed Hinkley C, they are going to be guaranteed about 9p/kWh no matter what the wholesale price of electricity is. So if it's 5p, they'll get a subsidy of 4p, if it's 4p, they'll get a subsidy of 5p etc.
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 2nd 2015
     
    Right.
    Not sure, but the prices by the half hour are here:
    http://www.bmreports.com/

    And yesterday/today prices are here:
    http://www.bmreports.com/bsp/SystemPrices.php?pT=SYSPRICE&dT=NRT

    So the price at the moment for non long term contracts (i.e. baseload, imports, hydro and some wind) is £42/MWh or 4.2p/kWh.

    So if 4 kW solar costs about £1000/kW installed, lasts 20 years and can export 3000 kWh, the cost of that will be (assuming no connection charges, admin charges etc) 6p/kWh
  7.  
    But another quirk used to make FIT's more acceptable or lucrative is that self consumption means that it's worth more like retail prices. i.e. nearer 15p/kWh (standing charge distorts this as well).

    Richard
  8.  
    Ok so we know the wholesale cost of electricity, but does feeding it directly into the distribution network without having to transform the voltage up, transmit it long distance and then transform the voltage back down make it any more valuable?
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 2nd 2015
     
    Not really in the scheme of things.
    Even local PV/other generation needs network support.

    I worked for a company that fitted two PV systems on one farm supply. Technically it was two separate address.
    The DNO had to check that the local transformer could cope when they found out. In total, it was 3 trips of about 100 miles, 2 days labour and a pile of paperwork.
    All that for 8 kWp of PV that probably only exported about 5 MWh/year.

    Most losses are though the local network, not the big, high voltage lines.
    Total system losses are estimated at 8%. But will vary a lot.
    It is a bit like getting Tesco to do a home delivery, the majority of the cost is getting the stuff picked at the store, then driven a few miles to your house. The small part of the cost is getting it from the main distribution centre to the store.
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