Forum Home» Green & Ethical MoneySaving

On-grid domestic battery storage

New Post Advanced Search

On-grid domestic battery storage

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
1.8K replies 198K views
Martyn1981Martyn1981 Forumite
10.8K posts
Part of the Furniture 10,000 Posts Name Dropper Photogenic
✭✭✭✭✭
edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
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.
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.
«134567183

Replies

  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    And diving straight in, a forum friend (not MSE) has just agreed to buy a battery system.

    It's part of a DNO (District Network Operator) evaluation scheme (offer now closed), and is discounted down approx 25% to £2k. It's a 4kWh system (but actually 8kWh LA).

    It's to be installed on Friday this week, and he's happy for me to post info on how the system goes, with info on changes to leccy import.

    To save 'the haters' the time and trouble of posting loads of negatives, both he and I agree that it's not going to be economic, as it probably needs to be nearer £1.5k to breakeven, but he's happy to have a play and see how it all goes, and how it works (or doesn't!)
    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.
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Centrica launches £19 million renewables and storage virtual market trial
    Centrica is to launch a £19 million pilot project which will assess the development of a virtual energy marketplace with renewables and storage at its heart.

    The programme will see Centrica’s distributed energy division work alongside Western Power Distribution, National Grid and the University of Exeter to develop a virtual market place for more than 150 homes and businesses in Cornwall.

    Starting next spring, Centrica will work with renewable generators and offer free smart technology upgrades to selected local residents, businesses and other large energy users. These will include new energy storage systems and micro-combined heat and power (CHP) systems.
    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.
  • michaelsmichaels Forumite
    24.8K posts
    Part of the Furniture 10,000 Posts Name Dropper
    ✭✭✭✭✭
    Seems to me if you were heating an indoor pool year round chp running when electricity spot prices were highest might work very well.

    In terms of domestic batts, does combining with both e7 and pv help the economics? Do any of the systems provide power during power cuts as for some this could be another addition to the value proposition.
    I think....
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    michaels wrote: »
    Seems to me if you were heating an indoor pool year round chp running when electricity spot prices were highest might work very well.

    In terms of domestic batts, does combining with both e7 and pv help the economics? Do any of the systems provide power during power cuts as for some this could be another addition to the value proposition.

    Some form of CHP would probably benefit from batts. Let's say you had one of those Flow boilers, and it's working hard, heating the house whilst you are still in bed, then the batts could soak up the leccy?

    E7 and batts probably depends on how high your usage is. If the batts are replacing lots (most?) of your evening/nighttime consumption, then you might not want E7. Or, the opposite, if the batts allow your PV system to supply almost all of your daytime leccy, then a higher daytime rate won't matter, thus saving you money in the winter nights.

    I haven't read up on all the systems, but the few I've gone through in a bit more detail, like the Powerwall and Powervault do have a dedicated socket for emergency use in a blackout.

    I don't know if they could cope with the short (but huge) load when a freezer cycles, but you'd be able to charge phones, torches, laptop. Plug in a radio etc to keep in touch and stay safe.
    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.
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Here's an article and video on one battery system. It's a bit too 'adverty' but it is the result of a competition, and does give some useful visual aids regarding what to expect:-

    Powervault winner unveiled as SPP storage survey uncovers confidence in 2017 market potential

    Also, that model, is (I believe) the same one that my forum friend is getting today. So that might help with getting an idea what is being talked about, as we go forward.

    On a personal note. The article is quite positive about the economics of storage as we go into 2017. That may well be true, but I can't help thinking that price reductions may outweigh savings for a few years.

    Yes, that's a bit negative, and only a gut feeling, but I'm not sure a leap of faith is warranted yet.
    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.
  • rugbyleaguesmaterugbyleaguesmate Forumite
    275 posts
    100 Posts Third Anniversary
    ✭✭
    http://arstechnica.co.uk/cars/2016/12/tesla-store-chiswick-powerwall-2-price-details/?comments=1

    Tesla UK information.

    Mart would having a bigger array justify the 6400 for a Tesla, I can't see it but was wondering if by having a larger system to top up the battery then this would improve the payback for the battery?
    6.72kw Pv Ja Solar 280w * 24 panels, Solar Edge inverter, South facing no shading.
    South Lake District, delightful view of Morecambe Bay. Not Saving up for a battery too expensive:j:mad::hello:

    July Solar target 769kw
  • OscargrouchOscargrouch Forumite
    3.7K posts
    Eighth Anniversary 1,000 Posts Photogenic
    ✭✭✭✭
    Martyn1981 wrote: »
    Here's an article and video on one battery system. It's a bit too 'adverty' but it is the result of a competition, and does give some useful visual aids regarding what to expect:-

    Powervault winner unveiled as SPP storage survey uncovers confidence in 2017 market potential

    Also, that model, is (I believe) the same one that my forum friend is getting today. So that might help with getting an idea what is being talked about, as we go forward.

    On a personal note. The article is quite positive about the economics of storage as we go into 2017. That may well be true, but I can't help thinking that price reductions may outweigh savings for a few years.

    Yes, that's a bit negative, and only a gut feeling, but I'm not sure a leap of faith is warranted yet.
    I would agree with your comment 'Mart': looking at the video, it is clearly a sales pitch; looking at it from other perspectives, whacking in all surplus energy into batteries; or for some rather than heating hot water (otherwise done by Gas) would be financial suicide. Too many questions for me, the main one; how long would the batteries last when you switch on the micro & oven at the same time after dark using in excess of 3-4 kW when you have, in my case a 2.5 kWp system that today generated 1.3 kWh & 1.24 kWh was used within the house on base usage? Sorry, I may be out of touch, but I am of the opinion that batteries for any domestic <4kWp system is the wrong tree to be embarking up (more so, if you have the luxury of an immersion heater for hot water and use items such as an iBoost)....coffee.gif
    2.5 kWp PV system, SSW facing, 45 Deg Roof. ABB Inverter, Monitor: 'Wattson'.
    Reg. for FIT Nov 2011. "It's not what you generate; it's how you use it that matters". One very clean Vauxhall Diesel Sri, £30.00 Road Tax: B)

    Definition of 'O's = kWh/kWp (kWh = your daily & accurate Generation figure) (kWp = the rated output of your PV Panels).
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    http://arstechnica.co.uk/cars/2016/12/tesla-store-chiswick-powerwall-2-price-details/?comments=1

    Tesla UK information.

    Mart would having a bigger array justify the 6400 for a Tesla, I can't see it but was wondering if by having a larger system to top up the battery then this would improve the payback for the battery?

    Hiya. To start here's a link to the Tesla GB site with the £6.4k price and specs of the PWII

    https://www.tesla.com/en_GB/powerwall

    Next, how much will a battery save you? I don't know if there's a cleverer way of working this out, so I'm going to repeat something I've posted elsewhere (not sure where now), on how I calculated my potential savings of 900-1,000kWh pa. Here goes:-

    Summer. I've got tons of generation, upto 34kWh in a single day, and an average of about 20kWh/day. However, my import is only 2.5kWh/day, so the most I can save is 2.5kWh x 90 days = 225kWh.

    Winter. Opposite of Summer (No, really!). I've got lots of import, upto 7kWh/day in December. However, my generation is lower, perhaps 3kWh/day December, so export probably ranges from 1 to 2 kWh. So the most I can save is 1.5kWh x 90 days = 135kWh.

    Spring/Autumn. Lots of import 4-5kWh, and lots of export (in excess of 4-5kWh) on average*. So the most I can save is 4.5kWh x 180 days = 810kWh.

    Total potential savings 1,170kWh pa.

    However, taking that * into account, means that some days in the Spring and Autumn I won't generate enough in bad weather, so I'd guesstimate a figure of 1,000kWh as a max.

    The figures also suggest to me that a battery capacity of 4kWh (available capacity) is enough for my needs.

    Note:
    1. For the winter there will be bad days with no export, but there will also be good days with lots of export, but less than the battery capacity, so this should balance out.
    2. In the summer there may be bad days, but days of less than 10kWh (more than I need) are very, very rare, so ignored.
    3. 4kWh battery capacity will be enough for 4-5kWh of daily use in the spring/autumn as some of that savings will be from micro battery cycles throughout the day as demand and supply fluctuate (eg clouds).

    So, what does all that mean to you, not a lot probably, it doesn't mean a lot to me. But hopefully it shows that we all individually need to look at our generation, import and estimated export, to make a calculated guess at what our potential annual import savings will be.

    From there, multiply the savings by your import price for an annual saving. You might need to deduct the export rate, but this will depend on changes to govt policy, and the amount you export. I currently export about 900kWh pa more than I get paid for, so I can value all my savings at import rates regardless.

    I'd also multiple by 10, for the number of years to give you a breakeven price on the kit, assuming you invest in something that has a 10yr warranty.

    Back to the question, does more PV help justify the battery investment. I suppose so, as more export means more potential for storage, but you need to ask some crucial questions first:

    1. Is the system so big that it's supplying lots of your leccy needs (such as my summer potential being small). A large PV system may have reduced your import so much that a large battery (or potentially any battery) isn't needed.
    2. Something michales raised, what about E7? If the large PV system is handling most of the daytime need, then E7 with cheaper nightime leccy might be a better deal.
    3. What about an EV in the future? This would throw everything out, and require new calcs, but probably supports large PV, batts and E7.

    These are personal musings, unsupported at this stage, so we all need to ponder how this will work, and see how folk with storage get on. [In other words, I don't really know what I'm talking about, so don't blame me!]
    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.
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    I would agree with your comment 'Mart': looking at the video, it is clearly a sales pitch; looking at it from other perspectives, whacking in all surplus energy into batteries; or for some rather than heating hot water (otherwise done by Gas) would be financial suicide. Too many questions for me, the main one; how long would the batteries last when you switch on the micro & oven at the same time after dark using in excess of 3-4 kW when you have, in my case a 2.5 kWp system that today generated 1.3 kWh & 1.24 kWh was used within the house on base usage? Sorry, I may be out of touch, but I am of the opinion that batteries for any domestic <4kWp system is the wrong tree to be embarking up (more so, if you have the luxury of an immersion heater for hot water and use items such as an iBoost)....coffee.gif

    Hiya Oscar. In the case of the PowerVault, it can supply 1.2kW, so would only support the 3-4kW draw. However the PWII can supply 5kW (7kW briefly). So you'd need to consider both size of the battery and potential needs, though personally I'd consider sustained demand, rather than worry about shorter peaks.

    However, for smaller PV systems, I think you are dead right. Until prices drop right down, especially for smaller batts, it's not going to be worth considering.

    But a potential candidate might be the Enphase battery as that comes in modular units of 1.2kWh, and each has a micro-inverter supplying up to 270W. So 4 units would give you 4.8kWh and 1.1kW.

    This seems like a nice all round package, and you can start small and keep adding batts. I don't know if this happened, but in early 2016 Enphase hoped to ship and sell 70,000 units in Australia, so this might be one to watch.

    Good news, you'd get loads of use out of a single unit, with it doing lots of micro-cycles through the day.

    Bad news, I don't know the price, but for one (small) unit expect it to be proportionately more than the PWII.

    So an I-boost is far simpler and easier at the moment.
    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.
  • Martyn1981Martyn1981 Forumite
    10.8K posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    (That's forum friend update 1 .... just in case!)

    Right, the system went in last Friday. No problems. Some initial concern that the Immersun came on, but turns out the Powervault has a 60s 'soft shutdown' from 1,200W discharge, and his Immersun jumped in to grab the export.

    Some background, the PV system is 3kWp, split roughly 2/3 south + 1/3 west.

    Obviously weather not great lately, and performance this time of year will be low, but the monitoring software shows the system busy with lots of charging and discharging.

    Mch onwards will probably be more interesting when generation (and available export) picks up, and the system starts to dent import. It will also be interesting to see how much use the Immersun now gets, as high value leccy storage comes before lower value heat storage.
    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.
Sign In or Register to comment.

Quick links

Essential Money | Who & Where are you? | Work & Benefits | Household and travel | Shopping & Freebies | About MSE | The MoneySavers Arms | Covid-19 & Coronavirus Support