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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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  1.  
    James, as Phil hinted, you'd be greener to charge your EV directly from the grid at 1am, when intensity is lowest.

    Export your PV during the day, or better still, charge a home battery and export it or use it at 6pm, when grid intensity is highest.

    Unfortunately most people are doing the exact opposite of this. They're looking at the financial side and discharging their home battery very late at night, instead of during the early evening peak. The subsidies that the rest of us pay (FIT/ET), are badly set up as they encourage that behaviour.
    • CommentAuthorborpin
    • CommentTime7 days ago
     
    Posted By: WillInAberdeenExport your PV during the day
    Excess PV of course :bigsmile:

    Posted By: WillInAberdeenThey're looking at the financial side
    Unless you have the desire and the finacial means to be philanthropic, that is inevitable. From the perspective of encouraging the installation of PV to help with CO2 emmissions, the financial setup has always been badly designed. This big generation companiues are not required to be loss making, so why should the small generator?

    With the introduction of the Octopus Agile type tarrif, it seems there should be no reason not to pay exporters a fair rate which will then encourage the use of batteries to charge overnight for local consumption during the day (while still exporting). If the Exporter was paid a fair rate, the need to store woul be reduced.
    • CommentAuthordickster
    • CommentTime7 days ago
     
    As the sun sets, we use electricity stored in Powerwall 2 to run our house. If the sun hasn't done it's job that day, we charge the battery on E7 overnight to see us through. We have therefore transferred our usage from the grid to overnight and done our bit to balance the grid.

    Not yet worked out what to do if EV arrives on the scene.
    •  
      CommentAuthordjh
    • CommentTime7 days ago
     
    Posted By: borpin
    Posted By: WillInAberdeenExport your PV during the day
    Excess PV of course :bigsmile:

    No, I think Will means export it all. He doesn't like people diverting it for their own use.
  2.  
    Uhhh... I literally just said "use it at 6pm, when grid intensity is highest", didn't you read before commenting?

    If you're claiming Export Tariff for 50% of your generation, paid for by me but also by people in serious energy poverty, then I'd like you to export at least 50%, thanks very much. Export some more if you want to be greener.

    Or maybe you are not claiming Export Tariff for 50% of your generation? In which case, fill your boots.

    Actually, I don't blame individuals for gaming the system for their own gain, though I chose not to. It's the system that needs changing, and the smart meter tariffs will help, as Borphin said.
    • CommentAuthorphiledge
    • CommentTime7 days ago
     
    I think the spirit of FIT is(was) that you export what you can over normal daytime usage, where normal doesnt include grabbing it all by way of PV diverters or daytime car/personal battery charging. As I understand it thats what the 50% export payment was intended for.
    • CommentAuthorphiledge
    • CommentTime7 days ago
     
    A post too late!!
    • CommentAuthorborpin
    • CommentTime7 days ago
     
    Posted By: djhNo, I think Will means export it all.
    Of course you actually cannot do this (think about it) unless you have zero consumption.
    • CommentAuthorborpin
    • CommentTime7 days ago
     
    Posted By: WillInAberdeenI literally just said "use it at 6pm, when grid intensity is highest"
    It makes me think that the whole balancing of the grid needs some serious reimagining. If there were lots of micro generation, storing excess during the day, to export it when CO2 intensity would peak, that could have an interesting impact. I do though go back to the need to make it financially sensible for those doing it.

    Those fleecing the 50% but never actually exporting do irritate me. Such a daft setup in the first place.
    •  
      CommentAuthordjh
    • CommentTime7 days ago
     
    Posted By: WillInAberdeenf you're claiming Export Tariff for 50% of your generation, paid for by me but also by people in serious energy poverty, then I'd like you to export at least 50%, thanks very much. Export some more if you want to be greener.

    You have completely the wrong perspective on the situation. The situation is that even with diversion I cannot use 50% of my generation. So I am subsidising you and people in serious energy poverty, not the other way around.

    To date, I have consumed 37% of my generation. So if I was feeling mean I might switch to a smart meter that did monitor my export, and/or move to a tariff that paid me for my export. So please stop accusing me and other people with PV of unjustified greed.
  3.  
    Once again, please read before commenting, as I think the 'unjustified accusations' are not being made by me. You could start with my last paragraph.
    •  
      CommentAuthordjh
    • CommentTime7 days ago
     
    I quoted what you said that I responded to.
  4.  
    Just to repeat.
    I was wondering the effect of running high powered loads (3kW+) off batteries in relation to there 'health'
    Rather than the ins and outs grid load matching for environmental benefit etc.
    :-)
    • CommentAuthorFlubba
    • CommentTime7 days ago
     
    James,

    I think it would very much depend upon the design of the battery pack and arrangement of the internal cells more than anthing else, number of cells ganged up in series vs parallel etc. High'ish draw generally shouldn't be a problem for Lithium battery chemistries as long as they are within a temperature range, more so than other chemistries. The limiting factor for a long life I would suspect is the usual overall cycles per cell although without googling I'd hope an easier life with lower discharge rates should enable a longer life.

    The main issue I see is the pairing of the overall battery capacity vs the inverter it's connected to, Powerwall 2 is upto 5kW IIRC and 13ish kWh so I would presume it would at least last it's warrantry period loading and unloading at 5kW. Same headache with any storage solution really, I note SSE decided to bump their proposed Coire Glas Pumped storage scheme from 600MW to 1500MW.

    Generally though I agree with Tony, home battery tech is along the lines of eco-bling in my opinion storage at home would be best done thermally or as a side effect of having an electric car. Even once we get to the point of having quantities of used EV battery packs available I feel this would be best managed in bulk with health and usage monitoring done on a 'professional' basis by folk who know what they are doing.

    I think in general storage is best done cost effectively both in terms of money and resources at a grid scale e.g. pumped storage projects or liquid air. We don't really have much storage at all and batteries are a drop in the ocean, they have their uses for grid ancillary services e.g. frequency response but as actual storage we are talking MWh scale.

    For actual grid scale storage to allow for a grid with much higher levels of intermittent renewables we are 100's of GWh's minimum if not TWh's. The obvious place to start would be to get enough storage on the grid to comfortably and reliably peak shave daily demand heading toward enough storage to ride through a few days of low wind.
    • CommentAuthorgravelld
    • CommentTime6 days ago
     
    Given the energy is most likely used by your neighbours, what if I only want to heat some hot water for my kid's evening bath and the neighbours need the energy for their Agas and hot tubs? Asking for a friend.
    • CommentAuthorowlman
    • CommentTime6 days ago
     
    AFAIK home batteries don't discharge into the grid unless they are smart and central controls ask them to. Then only a certain agreed % whereas your exported PV does feed local needs, I think. You may know something else.
    • CommentAuthorgravelld
    • CommentTime6 days ago
     
    Sorry, I'm referring to the "everything should be exported" argument.
    • CommentAuthorowlman
    • CommentTime6 days ago
     
    OK Dan, understood.
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