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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorwilliamd
    • CommentTime3 days ago
     
    A relative purchased an old house about 2 years ago and has renovated it including extensively insulating it and fitting an air source heat pump.
    The previous owner had fitted solar PV panels with eligibility for feed in tariff commencing in May 2013.
    My relative intends to build on an extension and wonders whether fitting further solar PV panels to this extension would be worthwhile financially. I assume that FIT will not apply to the new panels so is there any alternative subsidy available and how will this work in practical terms as it would presumably make sense if the existing panels are to remain on FIT.
    Thank you for your guidance...
    • CommentAuthortony
    • CommentTime3 days ago
     
    you may find that the fit evaporates if the system is changed
    •  
      CommentAuthordjh
    • CommentTime3 days ago
     
    Posted By: williamdThe previous owner had fitted solar PV panels with eligibility for feed in tariff commencing in May 2013.
    My relative intends to build on an extension and wonders whether fitting further solar PV panels to this extension would be worthwhile financially. I assume that FIT will not apply to the new panels so is there any alternative subsidy available and how will this work in practical terms as it would presumably make sense if the existing panels are to remain on FIT.

    I take it the rights to the FIT payments have transferred to your relative? I believe it is possible for the ownership of the FITs to belong to somebody other than the owner of the property.

    Any new panels will need to be connected separately to the grid, so that the metered capacity of the original installation is not affected. So separate inverter and metering. Also the total size of the system will need to remain within the 16A (3.68 kW) limit otherwise a G59 application must be made. An installer will be able to explain the details.
    • CommentAuthorphiledge
    • CommentTime3 days ago
     
    Im pretty sure the inverter limits its output to 16A on standard domestic installs so adding panels cant add anything to the maximum system output. Adding panels will increase overall generation but stay limited at 4kw/16A. When we got ours installed there was never any mention of panel output being limited, only a system limit managed by the inverter.

    Given the original install needed to be installed by an MCS accreditted installer to get FIT payments, I assume youd need an MCS installer to add any panels.
    •  
      CommentAuthordjh
    • CommentTime3 days ago
     
    Posted By: philedgeIm pretty sure the inverter limits its output to 16A on standard domestic installs so adding panels cant add anything to the maximum system output.

    You can't add panels to the current inverter without losing FIT.
    • CommentAuthorrevor
    • CommentTime3 days ago
     
    The way I understand it, but could vary with DNO is that if you want to export more than 3.6 kw you need their permission fill in forms (think the form has now changed) and maybe pay a fee. You can generate more than 3.6 Kw but obviously you would need an inverter for the size of panels and you can get a device which limits what you can send to the grid to 3.6 kw. So if DNO won't allow you to export more than you 3.6 kw I suppose you could use the extra generation yourself and maybe store it in a battery. I do not know what your FIT arrangement is but it could be that there will be no monetary benefit to you. There have been changes in the last year or so in that it was not possible to add extra panels or batteries without loosing your FIT however I understand that new generation of inverters get you the best of both worlds. Have a look at what Powervault
    have to offer I also think that Sola X have something as well, there may be others also.
  1.  
    Posted By: revorYou can generate more than 3.6 Kw but obviously you would need an inverter for the size of panels and you can get a device which limits what you can send to the grid to 3.6 kw. So if DNO won't allow you to export more than you 3.6 kw I suppose you could use the extra generation yourself and maybe store it in a battery.

    One advantage of having the capacity to generate more than 3.6kW but capped at 3.6 is that you will get more time when you are generating 3.6 (on dull days) than if your max output is 3.6kW. Of course you would have to do the sums to see how much extra PV is worth the expense.
    • CommentAuthorEd Davies
    • CommentTime2 days ago
     
    Posted By: djh: “…a G59 application must be made…”

    Slight update: AIUI, G83 has been replaced by G98 and G59 by G99 from April 2019:

    https://www.ssen.co.uk/G99G98Requirements/
  2.  
    Ive a fits system and a non fits systems.
    the no fits systems doesnt require MCS registration so can be fitted by a compedent roofer and a electrician rather than a specialist company , this may save on cost. if going over 16A potential export a G99 is required prior to connection , this may have a cost implcation.
    • CommentAuthorphiledge
    • CommentTime2 days ago edited
     
    Posted By: djh
    You can't add panels to the current inverter without losing FIT.


    Have you got a reference for that?

    Practically speaking, with our 4kw solaredge inverter that is limited to 16A output, the max recommended panel input is 5kw.
    •  
      CommentAuthornigel
    • CommentTime2 days ago edited
     
    Posted By: jamesingramIve a fits system and a non fits systems.
    the no fits systems doesnt require MCS registration so can be fitted by a compedent roofer and a electrician rather than a specialist company , this may save on cost. if going over 16A potential export a G99 is required prior to connection , this may have a cost implcation.


    I have two PV systems one fit eligible and the other not. I have signed up to Agile outgoing where they pay for exported energy, they will only accept this if both the systems are Mcse installed. So long term unless you will never export I would try and get an MCSE installed system.
    •  
      CommentAuthordjh
    • CommentTime2 days ago
     
    Posted By: philedgeHave you got a reference for that?

    Sorry, I'm now not convinced I understand current regs.
    • CommentAuthorrevor
    • CommentTime1 day ago
     
    This gives some info on FIT and batteries.
    https://www.solarguide.co.uk/solar-battery-with-smart-meter-will-not-stop-fit-payments#/

    So looks like you could add a battery and not loose your FIT you get to have your cake and eat it. Might be better option than another PV set up as you can buy back at cheap rate at night and use during the day.
    • CommentAuthorphiledge
    • CommentTime2 hours ago edited
     
    Had a bit of a search round and found the following on the Ofgem site

    https://www.ofgem.gov.uk/publications-and-updates/feed-tariffs-guidance-renewable-installations-version-15

    The section on modification refers to not exceeding the Total Installed Capacity which is defined as

    “the maximum capacity at which an Eligible Installation could be operated for a
    sustained period without causing damage to it (assuming the Eligible Low-carbon Energy
    Source was available to it without interruption), a declaration of which is submitted as
    part of the processes of ROO-FIT Accreditation and MCS certified Registration.”

    The way I read this is that if an inverter has a restricted output of 16 amp, the installations maximum operating capacity is the 16 amp limit regardless of the PV panels input capacity. Anyone read that differently???
    • CommentAuthorjamesingram
    • CommentTime1 hour ago edited
     
    Posted By: nigel
    Posted By: jamesingramIve a fits system and a non fits systems.
    the no fits systems doesnt require MCS registration so can be fitted by a compedent roofer and a electrician rather than a specialist company , this may save on cost. if going over 16A potential export a G99 is required prior to connection , this may have a cost implcation.


    I have two PV systems one fit eligible and the other not. I have signed up to Agile outgoing where they pay for exported energy, they will only accept this if both the systems are Mcse installed. So long term unless you will never export I would try and get an MCSE installed system.


    A good point Nigel , one I hadnt consider.ed
    Personally I get a high rate of FITs with my initial system and the 50/50 export payment, so just see the 2nd systems as adding additonal capacity using that funding to pay for it and other improvements so havent really considered the export from the 2nd system.

    50% of the 2nd system faces NW giving us some generation until sunset which usually get used. the majority of our 2 systems faces SE
    • CommentAuthorjamesingram
    • CommentTime56 minutes ago edited
     
    Posted By: philedgeHad a bit of a search round and found the following on the Ofgem site

    https://www.ofgem.gov.uk/publications-and-updates/feed-tariffs-guidance-renewable-installations-version-15

    The section on modification refers to not exceeding the Total Installed Capacity which is defined as

    “the maximum capacity at which an Eligible Installation could be operated for a
    sustained period without causing damage to it (assuming the Eligible Low-carbon Energy
    Source was available to it without interruption), a declaration of which is submitted as
    part of the processes of ROO-FIT Accreditation and MCS certified Registration.”

    The way I read this is that if an inverter has a restricted output of 16 amp, the installations maximum operating capacity is the 16 amp limit regardless of the PV panels input capacity. Anyone read that differently???


    My understanding is your reading is correct.

    From memory the issue with expanding and existing system that receives FITs is it then requires an update to its registration which then in turn results in it being classified under the current FITs band.
    The result of this when FITs rates were dropping regularly was you would end up on a lower tariff after registering.
    Now FITs has stopped to new installs Im not sure what the situation is.

    At the time I personally thought it wise just to leave any eixisting system receiving funding alone and to not rock the boat and risk loss of tariff
    • CommentAuthorrevor
    • CommentTime7 minutes ago
     
    I need to get my head around these regs as well. My proposed installation is gathering pace now and my inverter is G98 G 99 and G 100 compliant It seems that the G100 bit is about export limitation. The inverter can be programmed to not export or export what you want. However my system will be 6Kw and the proposal I think from the installer is to limit the output to 3.6 so don't need to make a G99 application although I would like to export everything I cannot use. Think that historically in our area everyone with SPV has been limited because of grid capacity.
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