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On-grid domestic battery storage

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
1.8K replies 200.2K views
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  • Martyn1981Martyn1981 Forumite
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    tony541 wrote: »
    If a bank of panels plus a 10kw battery system was say £10000, which is probably too cheap a price, then how many years would it take to break even.

    That's probably doable today. A 4kWp system for £5k, plus £5k for a Tesla PWII (at reduced VAT rate). Assuming a decent discount from the installer for having both.

    Break even, if we ignore lost interest (naughty, but I'm tired).

    Then around £500pa from FiTs, export and leccy savings, so 20yrs.

    I appreciate that this is not great, but it's still early days for batt storage, prices will fall both from expanded production, and reduced install costs. Also the opportunity to sell stored leccy to the grid could add significantly to this as the business model grows - In Aus folks have at times, been selling at A$1/kWh (56p/kWh) when peak prices hit A$1,400/MWh.

    Regarding AGW I have no doubts. The experts are certain, and this has only grown and become more consistent over the last 50yrs. The scientific papers produced by the FF industry also confirm AGW, though these were successfully hidden for decades. As no peer reviewed scientific papers oppose AGW, nor provide an alternative to why the planet is warming when we are in a cooling period, who am I to disagree.

    From an insurance point of view, if there was a 97% chance of serious harm and financial loss, you would take action. Even if the risk was 3%, you would take action, so either way, spending money is worth it. After all:-

    What if it's a big hoax and we create a better world for nothing?
    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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    Martyn1981 wrote: »
    That's probably doable today. A 4kWp system for £5k, plus £5k for a Tesla PWII (at reduced VAT rate). Assuming a decent discount from the installer for having both.

    Break even, if we ignore lost interest (naughty, but I'm tired).

    Then around £500pa from FiTs, export and leccy savings, so 20yrs.

    I appreciate that this is not great, but it's still early days for batt storage, prices will fall both from expanded production, and reduced install costs ...
    Hi

    Simply looking at the price differential between Tesla's standard and extended range trucks gives an idea of where the price of batteries will be going over the next few years .... I'll be watching carefully for Powerwall2 and other domestic battery system price movements, but will be staying clear until a fully installed unit is available for well under £150/kWh and probably much closer to the £100 mark ... unless there's an incentive scheme to kick-start the home energy storage market!

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • silverwhistlesilverwhistle Forumite
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    zeupater wrote: »
    It's almost certainly the case that (even with the much reduced FiT rates) installing solar PV would provide the homeowner with more energy flexibility and a better ROI than solar thermal would, even if accessing the RHI scheme. Z


    I haven't read your link, but I'd add that putting in cabling is a lot easier than retrofitting piping.

    I get hot water from solar (looking forward to tomorrow's forecast sun!) by the simple expedient of an electric immersion heater in an existing tank. Solar hot water would have been a real pain.
  • edited 15 February 2018 at 12:00AM
    zeupaterzeupater Forumite
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    edited 15 February 2018 at 12:00AM
    I haven't read your link, but I'd add that putting in cabling is a lot easier than retrofitting piping.

    I get hot water from solar (looking forward to tomorrow's forecast sun!) by the simple expedient of an electric immersion heater in an existing tank. Solar hot water would have been a real pain.
    Hi

    The pipe runs aren't too bad if the cylinder is upstairs and there's a loft above it ... it's just a case of replacing the existing cylinder and running some semi-flexible insulated tubing up into the loft and through the roof to where the panels are ....

    The main thrust of the article seems to be that thermal has stood still and watched as PV has gobbled up their market with a more flexible form of energy ... the conclusion is interesting and pretty damning, seeming to suggest that when home battery prices fall the thermal market will seriously suffer ...
    ... Photovoltaic and proportional diversion technologies have seriously eroded the base domestic hot water provision market position and the provision of affordable and justifiable battery storage systems will accelerate this process. Apart from a few cases where maximising performance over a limited area is important, unless the installed costs of UK solar thermal are seriously reduced over the next few years, it's highly likely that the market for the product will collapse, this likely being the case in many high-latitude countries ...
    On the hot water front, we're starting to get some decent temperatures from our thermal system already, around 40C on an almost depleted cylinder earlier this week, but tonight needed a slight 'top-up' from the GCH after a couple of dull days ... if (and that's a big if!) the forecast on the BBC red button is right the next 3 days don't look too bad so we might get some really hot water and start to wind down the gas usage ....

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • pile-o-stonepile-o-stone Forumite
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    Do you have a pressurised solar thermal system Z? Does the pressure ever have to be topped up and do you have to refresh the antifreeze inside the pipework? I read a report on solar vs thermal and the major point for me was the ability to use the generated energy from PV for something more than just heating water, the other points in the article were about the ability for solar thermal to 'destroy itself', where it either freezes in winter or boils in summer and that maintenance was a lot more than the 'fit and forget' of solar PV. I felt that this was probably a little overblown and would be interested to know if this is actually an issue?
    5.18 kWp PV systems (3.68 E/W & 1.5 E).
    Solar iBoost+ to two immersion heaters on 300L thermal store.
    Vegan household with 100% composted food waste
    Mini orchard planted and vegetable allotment created.
  • edited 15 February 2018 at 3:29PM
    zeupaterzeupater Forumite
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    edited 15 February 2018 at 3:29PM
    Do you have a pressurised solar thermal system Z? Does the pressure ever have to be topped up and do you have to refresh the antifreeze inside the pipework? I read a report on solar vs thermal and the major point for me was the ability to use the generated energy from PV for something more than just heating water, the other points in the article were about the ability for solar thermal to 'destroy itself', where it either freezes in winter or boils in summer and that maintenance was a lot more than the 'fit and forget' of solar PV. I felt that this was probably a little overblown and would be interested to know if this is actually an issue?
    Hi

    The system is sealed & has a pressure expansion vessel to raise water boiling point when stagnation happens. Our system is well designed to match our hot water usage so stagnation is rare, but on the odd occasion the solar circuit fluid approaches somewhere around double the temperature of boiling water.

    We keep an eye on the condition of the 'glycol' using a small window in the system, but as it doesn't overheat too often it's not really a problem ... you could run the system without anti-freeze and use have the controller cycle the system according to sensor temperatures to prevent freezing if it's a worry.

    I agree that energy provided by PV has more uses and is therefore likely to be of more use to homeowners, been saying it for years ... it's also raised in the linked article, so it looks like I'm not the only one !.

    As for thermal's ability to 'destroy itself', that's where balancing the design comes into play ... oversize the collector area compared to hot water storage in a cylinder & you'll have hot water all year, but stagnation will occur almost every day in the summer - same for the storage:usage ratio ... the less stress there is on the system, the longer it'll likely last ...I know of a system which is still working after over 40 years after some early 'teething' problems (undersized cylinder & self-built control!), so as long as an installation is well thought though there's no reason to expect that any other reasonable system shouldn't last that long too! ... yes it does need a little more TLC than a PV system, but not as much as a PV salesman would describe!

    Over the past couple of days I've noticed that our system has a little air in it which is causing noise as it passes through the cylinder coil - it's probably the same amount as has been there for years, but it seems that all of the small bubbles have combined, so I'll either need to separate & vent this out at some time or leave it for the pump to chop into smaller ones as the temperatures & run time increase ... also, we have some discolouration of a couple of tubes, doesn't look like blown vacuum, but maybe replacement or just cleaning, maybe nothing, but that's 'maintenance', similar to panel, cable, isolator & inverter issues which need to be accepted with PV!

    I think that the relative efficiencies raised in the article are the reason why a requirement for thermal will continue and agree that the combination of thermal & PV provides a really good overall solution .... For comparison, so far today our PV has generated just under 7kWh, with the thermal collecting over 4kWp.t ... same roof, same orientation, same day just that the thermal covers 1/4 of the area of the PV ... still looking good for when battery prices fall ..

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • ASavvyBuyerASavvyBuyer Forumite
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    Just noticed that Octopus Energy have launched an "Agile" tariff.

    https://octopus.energy/agile/

    Could make the economics of having a battery worthwhile if able to charge it up from solar PV during the day & import when rates are low.

    This could cancel out the need to import from 4pm-7pm when the rates are very high.
    4kWp, W roof, 30° pitch, Solar Edge Inverter + Optimisers. South Wales Valleys, Installed Aug 2015. Octopus Go Faster Electric Tariff.
    Solic 200 Diverter, Toshiba Ultra High Efficiency Air Conditioner/Heat Pump, Kia Soul & Renault Zoe EV's & Ohme Charger.
  • pile-o-stonepile-o-stone Forumite
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    Thanks Z, lots of good information. Always good to hear from people who are actually using a particular technology.
    5.18 kWp PV systems (3.68 E/W & 1.5 E).
    Solar iBoost+ to two immersion heaters on 300L thermal store.
    Vegan household with 100% composted food waste
    Mini orchard planted and vegetable allotment created.
  • ASavvyBuyerASavvyBuyer Forumite
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    Not sure if Mart or someone has posted this before, but it may be useful for someone.

    PETE Project
    4kWp, W roof, 30° pitch, Solar Edge Inverter + Optimisers. South Wales Valleys, Installed Aug 2015. Octopus Go Faster Electric Tariff.
    Solic 200 Diverter, Toshiba Ultra High Efficiency Air Conditioner/Heat Pump, Kia Soul & Renault Zoe EV's & Ohme Charger.
  • ASavvyBuyerASavvyBuyer Forumite
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    Found this guide when looking for "official" information concerning Solar PV & Battery Storage.

    https://www.bre.co.uk/filelibrary/nsc/Documents%20Library/NSC%20Publications/88031-BRE_Solar-Consumer-Guide-A4-12pp.pdf

    It is from 2016, so could do with updating, but even so, provides a fair bit of info.
    4kWp, W roof, 30° pitch, Solar Edge Inverter + Optimisers. South Wales Valleys, Installed Aug 2015. Octopus Go Faster Electric Tariff.
    Solic 200 Diverter, Toshiba Ultra High Efficiency Air Conditioner/Heat Pump, Kia Soul & Renault Zoe EV's & Ohme Charger.
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