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    • Martyn1981
    • By Martyn1981 5th Dec 16, 2:57 PM
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    Martyn1981
    On-grid domestic battery storage
    • #1
    • 5th Dec 16, 2:57 PM
    On-grid domestic battery storage 5th Dec 16 at 2:57 PM
    Hello!

    Right, as discussed elsewhere, battery storage for self generation (typically PV) is interesting (to some), and gathering momentum in the UK. So here's a thread to discuss it, and watch it develop.

    I've called it on-grid, as off-grid is so much more specialised. And domestic as commercial scale storage, or grid scale can be chatted about on the Green & Ethical energy issues thread.

    So, where are, well this article lists about 20 systems that are available or should be available soon:-

    Introducing CleanTechnica’s New Home Battery Overview Page

    Jumping straight in with personal opinions:-

    Economical - Not yet. Prices are falling fast, the range of products is expanding fast, and large numbers are being deployed in some countries, either because the price of leccy is high (Australia & Hawaii) or because subsidy schemes exist (Sweden & Germany).

    Where are we today. My needs are a 4kWh system. That's 4kWh of useable capacity, which would mean about 8kWh of lead acid (LA), or about 5kWh of lithium ion (Li-ion). My research has found batts in the high £2k and up range. I need the price to be nearer to £1.5k.

    The Tesla Powerwall II, installed is approx £6.5k, which works out at about £2.2k for 5kWh, but of course, it doesn't work quite like that, as smaller systems will cost proportionately more.

    Environmental - Tricky one this (to say the least). Until storage is needed, it's not environmental. Renewable energy (RE) generation currently displaces gas generation, which is a demand follower. Once gas generation is pushed down to zero (at times) we need storage, but we aren't there yet.

    However, to push gas generation down to zero, we need more RE, and to ensure it is viable/economic/profitable, we will need storage - chicken and egg situation.

    The advantage of storage to the environment, is to take peaks of RE and timeshift them to peaks in electricity demand. On a domestic level, this works quite well as PV generates during the day into the afternoon (or evening) depending on the month, so any stored leccy is available for the evening peak 5pm to 7pm.

    That's the background, and now here's a thread to discuss options, prices, economics, and watch things unfold. Enjoy.
    Just 'call me Mart'. Cardiff. 5.58 kWp PV systems (2.4 ESE & 1.18 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
Page 5
    • Martyn1981
    • By Martyn1981 20th Mar 17, 4:46 PM
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    Martyn1981
    Your link didn't work for me. This did though.

    https://www.recc.org.uk/pdf/guidance-on-supplementary-solar-pv-equipment.pdf

    Also, and interestingly the paper suggests that we will be moving from deemed to actual export with smart meters. This is the first I've heard of this. Every other time smart meters have been mentioned I've always heard that same story, which is that they are only being used to measure import and so are of no benefit to us for export. If export metering goes ahead then for battery storage to pay for itself then costs will need to come down to about a quarter of what they are today, unless of course we are all forced into demand led pricing for import in which case they may well become viable at a higher price.
    Originally posted by Exiled Tyke
    For myself, I currently export about 900kWh pa more than I'm paid for, so it wouldn't reduce my export income v's today, but if my export was to be metered, the storage would reduce my potential of getting more export payments in the future.

    Then again, don't forget the Aussie model that's already in use where domestic battery owners can sign up, and the 'company' negotiates a sale price for stored leccy during peak times, sometimes as high as AUS$1/kWh (when spot prices hit AUS$1,400/MWh). In that situation many of us might be happy to sell/discharge our batts onto the local grid during evening peaks - though it's probably the case that UK spot prices would be peaking in the lower generation months when we may not have much to sell.

    This subject ain't getting any easier.
    Just 'call me Mart'. Cardiff. 5.58 kWp PV systems (2.4 ESE & 1.18 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 20th Mar 17, 6:41 PM
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    zeupater
    This may be a daft question and not even sure if this would work, but has anyone tried using a UPS (Uninteruptable Power Supply) normally used for PC equipment, as "Domestic Battery Storage" for alternative relatively low power equipment?

    For example; charging it up during the day, (from solar power) and then using it to power a LED TV or LED lighting during the evening, with power switched off at the socket.

    The payback time may make it not worth it, but there are some smaller UPS's available for under £100 which may store enough power.
    Originally posted by ASavvyBuyer
    Hi

    The issue is that UPS systems aren't normally based on deep cycle usage - they're usually designed to be continually topped up so as to be available for occasional power outages ... as for 'enough power', well that depends on what you want to power and for how long, for example for ~£100 you may just be able to provide ~700W for around 2 minutes .... a decent capacity UPS which is capable of supporting an IT server environment at (say) 11kVA for ~60minutes would cost considerably more than a 13kWh Tesla Powerwall battery system.

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • ASavvyBuyer
    • By ASavvyBuyer 21st Mar 17, 8:21 AM
    • 277 Posts
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    ASavvyBuyer
    Hi

    The issue is that UPS systems aren't normally based on deep cycle usage - they're usually designed to be continually topped up so as to be available for occasional power outages ... as for 'enough power', well that depends on what you want to power and for how long, for example for ~£100 you may just be able to provide ~700W for around 2 minutes .... a decent capacity UPS which is capable of supporting an IT server environment at (say) 11kVA for ~60minutes would cost considerably more than a 13kWh Tesla Powerwall battery system.

    HTH
    Z
    Originally posted by zeupater
    As mentioned, was not thinking of using anything that took a lot of power ("a LED TV or LED lighting") so maybe less than 100 watts for the tv, or less than 15 watts for the lighting, on for 3-5 hours, so a maximum of 500 watts for the TV or 75 watts for the LED lighting.

    However, it seems that the batteries used in UPS's, are the type that do not like being discharged & charged up on a regular basis, so may not last that long.
    Rhondda Cynon Taf, 4kw, W roof, 30° pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • ASavvyBuyer
    • By ASavvyBuyer 21st Mar 17, 11:13 AM
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    ASavvyBuyer
    As mentioned, was not thinking of using anything that took a lot of power ("a LED TV or LED lighting") so maybe less than 100 watts for the tv, or less than 15 watts for the lighting, on for 3-5 hours, so a maximum of 500 watts for the TV or 75 watts for the LED lighting.

    However, it seems that the batteries used in UPS's, are the type that do not like being discharged & charged up on a regular basis, so may not last that long.
    Originally posted by ASavvyBuyer
    Done a quick count on the figures for payback time, and it does not seem worth it. Max could save with a low power LED TV, is about £20 a year; so would take at least 5 years to cover it's cost and batteries probably would not last that long.
    Rhondda Cynon Taf, 4kw, W roof, 30° pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • zeupater
    • By zeupater 21st Mar 17, 4:36 PM
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    • 4,336 Thanks
    zeupater
    As mentioned, was not thinking of using anything that took a lot of power ("a LED TV or LED lighting") so maybe less than 100 watts for the tv, or less than 15 watts for the lighting, on for 3-5 hours, so a maximum of 500 watts for the TV or 75 watts for the LED lighting.

    However, it seems that the batteries used in UPS's, are the type that do not like being discharged & charged up on a regular basis, so may not last that long.
    Originally posted by ASavvyBuyer
    Hi

    Using a 500W on a £100 UPS may give you around 3 or 4 minutes of off grid usage, with a decent LED TV you may get 15-20minutes whilst the batteries are still in good condition ...

    Regarding the battery types (highlighted in red) ... Correct, that's why I mentioned you'd need a deep cycle battery system ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • zeupater
    • By zeupater 21st Mar 17, 4:47 PM
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    • 4,336 Thanks
    zeupater
    Done a quick count on the figures for payback time, and it does not seem worth it. Max could save with a low power LED TV, is about £20 a year; so would take at least 5 years to cover it's cost and batteries probably would not last that long.
    Originally posted by ASavvyBuyer
    Hi

    Using a standard UPS on a deep cycle basis will kill your batteries in next to no time, you'd be lucky if you'd save anywhere near the first year's £20 before the system stops accepting charge or delivering power for any acceptable time ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 23rd Mar 17, 12:19 PM
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    Martyn1981
    I've just been watching an oldish interview on WA's (Western Australia) roll out of PV and storage.

    I thought it worth mentioning on here as the speed is catching everyone out, and WA's energy minister has stated a couple of things.

    Firstly that by 2025 Perth would get all of its daytime electricity from solar, and secondly, that also by 2025 that Perth would get 70% of its electricity from solar and batteries. [Edit: Further reading seems to suggest his claims relate to the whole of WA, not just Perth. M.]

    Given the scale and speed of rollout needed to meet these claims/assumptions, I though it was worth mentioning on this thread as it seems to confirm thoughts that Australia will be a major driver of storage, and will hopefully help to bring prices down fast / faster.

    Distributed Solar and Storage: Disrupting Australia's Energy System

    The Perth claims are in the last 5 minutes, and relate to statements made in 2015.
    Last edited by Martyn1981; 23-03-2017 at 12:21 PM. Reason: Added an edit
    Just 'call me Mart'. Cardiff. 5.58 kWp PV systems (2.4 ESE & 1.18 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Ectophile
    • By Ectophile 24th Mar 17, 12:02 PM
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    • 1,487 Thanks
    Ectophile
    I've just had a visit from the guy who sold me my solar panels back in 2011. He's running a different company now, after the solar industry collapsed, so the new one does other sorts of building maintenance as well as solar.

    He says he can fit a new Solax inverter and battery unit for around £5.5K. The battery has a capacity of 4.8kWh, of which 3.85kWh would be usable. That's with a 10 year warranty on the inverter and 5 years on the battery (expected life 10 years). Apparently, it can even operate in islanded mode if there's a power cut.

    My old inverter is about to go out of warranty (5.5 years), so I need to consider that as well.

    I haven't done the maths yet to work out what the payback period is likely to be.
    If it sticks, force it.
    If it breaks, well it wasn't working right anyway.
    • ASavvyBuyer
    • By ASavvyBuyer 24th Mar 17, 12:53 PM
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    • 459 Thanks
    ASavvyBuyer
    I've just had a visit from the guy who sold me my solar panels back in 2011. He's running a different company now, after the solar industry collapsed, so the new one does other sorts of building maintenance as well as solar.

    He says he can fit a new Solax inverter and battery unit for around £5.5K. The battery has a capacity of 4.8kWh, of which 3.85kWh would be usable. That's with a 10 year warranty on the inverter and 5 years on the battery (expected life 10 years). Apparently, it can even operate in islanded mode if there's a power cut.

    My old inverter is about to go out of warranty (5.5 years), so I need to consider that as well.

    I haven't done the maths yet to work out what the payback period is likely to be.
    Originally posted by Ectophile
    If you estimate the inverter to be worth about £1k, that leaves £4.5k's worth of electricity to import over the next 5-10 years. With already having Solar Panels, is it likely that you would import that much during the lifetime of the battery?

    Since we had Solar Panels installed, we import less than £250 worth a year (including standing charge), so it would take over 18 years to break even.
    Last edited by ASavvyBuyer; 24-03-2017 at 12:56 PM. Reason: typo
    Rhondda Cynon Taf, 4kw, W roof, 30° pitch, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • Martyn1981
    • By Martyn1981 24th Mar 17, 2:19 PM
    • 5,303 Posts
    • 8,967 Thanks
    Martyn1981
    He says he can fit a new Solax inverter and battery unit for around £5.5K. The battery has a capacity of 4.8kWh, of which 3.85kWh would be usable. That's with a 10 year warranty on the inverter and 5 years on the battery (expected life 10 years). Apparently, it can even operate in islanded mode if there's a power cut.

    My old inverter is about to go out of warranty (5.5 years), so I need to consider that as well.

    I haven't done the maths yet to work out what the payback period is likely to be.
    Originally posted by Ectophile
    Hiya, having a ponder here, ASavvyBuyer has broken it down sensibly, so let's say £4.5k for the battery.

    Loads of negatives I'm afraid.

    Firstly, 5yr warranty isn't enough, and 10yr life expectancy is too short too.

    Secondly, 3.85kWh useable, let's go super optimistic and assume you get 5kWh out of it each day, and it lasts 10yrs, that's 18,250kWh, which at 12p import would be worth £2,190, so half the cost of the battery. £4,500 / 18,250kWh gives you a cost of nearly 25p/kWh stored.

    Thirdly, Tesla PWII installed is £6.3k, I now that's £2k more but it has a useable 13.5kWh ..... just for comparison.

    Fourthly, also for comparison, I got quotes, including install from Powervault, which are approx:
    4kWh useable (8kWh) lead acid - £2.7k 5yr warranty
    4kWh useable (4.4kWh) Li-ion - £3.8k 10yr warranty
    6kWh useable (6.6kWh) Li-ion - £4.9k 10yr warranty


    So, still far too expensive, prices still falling, and a good chance that prices will fall faster each year, than current savings, so even if it was questionably viable today, it would probably still be worth waiting for a few years till we see where the market is going, and if prices are stabilising.


    Lastly, you mention it can operate in Islanding mode during a power cut. Worth double checking that. Islanding allows the inverter to keep working even if the grid is down, some can do this, but they are usually more expensive and 'meatier' inverters.

    You may be absolutely correct, or he may have meant that the battery has a dedicated socket for you to plug essentials into during a powercut, such as freezer, laptop, battery charger (flashlights) phone etc. Lots of the batts seem to have one of these, but the PV system would be shutdown.

    Islanding is great if you need it, with lots of powercuts, but otherwise it probably adds a lot of cost.
    Just 'call me Mart'. Cardiff. 5.58 kWp PV systems (2.4 ESE & 1.18 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Ectophile
    • By Ectophile 26th Mar 17, 7:21 PM
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    Ectophile
    I was told that the islanded mode was a matter of flipping a switch, so presumably it's a mode that the system can be put into when disconnected from the mains.

    But I rarely get power cuts here, in an urban area.

    It's not looking very cost-effective when you do the maths.
    If it sticks, force it.
    If it breaks, well it wasn't working right anyway.
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