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On-grid domestic battery storage

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
1.8K replies 199.3K views
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  • CardewCardew Forumite
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    Unless the Government or one of its agencies act quickly to regulate this market the cowboys will soon be operating with outrageous claims of savings.
  • NigeWickNigeWick Forumite
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    Martyn1981 wrote: »
    As the Tesla PWII is too big for me, I'm more and more convinced that a few years are needed, as I forsee a big battery battle, with a lot of fatalities in the coming years .... but ..... some very good winners. :think:
    Tony Seba believes about four years for prices to come down far enough to make it a no brainer.
    The mind of the bigot is like the pupil of the eye; the more light you pour upon it, the more it will contract.
    Oliver Wendell Holmes
  • Martyn1981Martyn1981 Forumite
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    Momentum is growing in domestic market.

    Sonnen reports record solar storage sales for August
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • zeupaterzeupater Forumite
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    Hi All

    Not domestic, but interesting development from a power density aspect ....

    samsung-electric-car-batteries

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • NigeWickNigeWick Forumite
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    zeupater wrote: »
    interesting development from a power density aspect ....
    Doesn't say whether it's the Japanese, NEDC, EPA or real world distance though.

    That said, EPA says 107 per charge for my 30kWh Nissan Leaf and I get a fractsh more than that on a long journey. I also get about 150 miles per charge when tootling round town and to my allotment.
    The mind of the bigot is like the pupil of the eye; the more light you pour upon it, the more it will contract.
    Oliver Wendell Holmes
  • zeupaterzeupater Forumite
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    NigeWick wrote: »
    Doesn't say whether it's the Japanese, NEDC, EPA or real world distance though.

    That said, EPA says 107 per charge for my 30kWh Nissan Leaf and I get a fractsh more than that on a long journey. I also get about 150 miles per charge when tootling round town and to my allotment.
    Hi

    I'd say it's more related to the physical size of a battery pack than anything else .... cylindrical cells aren't really volume efficient when packed together ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • I have a 3.8 kWh nominal PV ground based array 100m from my house which is at the end of a long country lane. Many of my neighbours now have PV systems. On sunny days I often get a message on my SunnyBoy inverter saying that it has shut down owing to grid instability. I note that the output voltage is often at 260V or above and assume my inverter is programmed to shut down at above about 260/265V.
    The problem is most likely that the local grid line cannot take the generation load from the group of houses if local usage is low. I'm interested in possible cures for this problem since I'm one of the very fortunate PV generators currently receiving 50.67p/kWh (that includes the assumed 50% export tariff element) on all my output whether or not I use that output in my home. I started generating in 2012. Initial annual output was about 3.9MWh but after three years has fallen to about 3.5MWh as more local generation has come on stream. My panels remain efficient - the inverter was reading 4.1kWh yesterday for a brief period. My annual usage after the PV array installation was initially 2.9MWh but has risen to about 3.2MWh recently, I suspect because of the lag in inverter start up following a grid instability outage when my house load increases.
    I am considering buying a battery pack to take the output from my array when the AC output voltage rises above the grid-acceptable level. The economics don't work yet, but the possibility of time dependent pricing of mains supply electricity is a factor to bear in mind.
    My technical question is can a battery take the DC output from my array and store it before it goes through the inverter, and then discharge through the inverter at a later time so as to give a total generated output back at the level I enjoyed before the grid instability problem? Can the battery be made to start and stop storing at specified times or automatically if my inverter AC output voltage rises above a set trigger voltage so as to stop the inverter shutting down?
    Thanks for your help.
  • Martyn1981Martyn1981 Forumite
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    David_RC wrote: »
    My technical question is can a battery take the DC output from my array and store it before it goes through the inverter, and then discharge through the inverter at a later time so as to give a total generated output back at the level I enjoyed before the grid instability problem? Can the battery be made to start and stop storing at specified times or automatically if my inverter AC output voltage rises above a set trigger voltage so as to stop the inverter shutting down?
    Thanks for your help.

    Hiya and welcome. Some batteries are designed to work on the DC side, this can even be used to allow generation above 3.68kW without exceeding the DNO limits.

    However, you will need an inverter that can do this, plus you may find that the inverter still has to shutdown if it sees grid voltage exceed 253V, as that's the max allowed and any PV gen will push it higher. [Some older inverters may go higher depending on when they were installed and the rules then, but not now.] There are also islanding inverters that can operate with the grid down but this gets even more complicated and regulatory.

    Your DNO is required to maintain the voltage at 230V (-6% / +10%) but more importantly they are required to maintain this level even with SSEG's (small scale electricity generators) on that line. So worth speaking to them so they can monitor how often it happens and see if it can be resolved simply by changing the tappings, or by other works.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn
    Thanks for the reply to my post which seems to have vanished. What is the DNO that I should contact to discuss the high voltage at my inverter and how do I find their contact details? As you can see I'm new to posting on this site and to electricity generation.
    Thanks
    David RC
  • Martyn1981Martyn1981 Forumite
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    David_RC wrote: »
    Martyn
    Thanks for the reply to my post which seems to have vanished. What is the DNO that I should contact to discuss the high voltage at my inverter and how do I find their contact details? As you can see I'm new to posting on this site and to electricity generation.
    Thanks
    David RC

    Hiya David, sorry I went straight into acronym mode, very rude of me.

    The high voltage network is run by the National Grid, then the low voltage network is run by about 10(?) companies known as the district network operators. Mine in the south west is Western Power Distribution. You can Google yours, or it may be mentioned on your leccy bill as a contact number for problems.

    Hopefully they will be helpful and install a monitor to see how high the voltage is, and how often it goes too high. Mine tends to sit around 238-241V but it will vary all day. I had one inverter shutdown, but that was about 3 years ago and on a sunny Sunday afternoon when demand will be light and voltage can be expected to rise.

    Your inverter might display grid voltage so you can keep an eye too. Whilst 230V is technically the UK voltage this is really an attempt to move closer to the European 220V but I believe in name only, hence the revealing -6%/+10% range.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
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