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Solar PV battery options



  • Registered Users Posts: 82 ✭✭Murt2

    Thanks. If you hear of anyone that wants to part with one please let me know...

  • Registered Users Posts: 421 ✭✭Geeyfds53573

    I have a Pylontech US2000B 2.4 kWh Battery with cables and bracket for sale if anyone wants to make an offer. <1 year old never abused. PM me.

  • Registered Users Posts: 7 theRed73

    After binge reading 83 pages here I'm really impressed with the depth of knowledge that you guys have shared here!

    I'm planning to pull the trigger on a decent sized array on a garage I'm building and go done the DIY battery route. I'm consuming about 16MW per year so committed to a 10KWhr battery and likely a second. That would give me 2x 16s packs.

    I have a question regarding inverters. Should I stick with an installer provided hybrid like to solis 6KWhr (with 100A charge/discharge) or opt for dedicated storage inverters?

    Can I plug both packs into the solis or would the second pack requir a dedicated inverter?


  • Registered Users Posts: 5,744 ✭✭✭championc

    With two packs, they are daisy-chained for the BMS but joined at some form of switch / busbar for the DC cables

    A separate Storage Inverter allows the batteries to be located in a separate location to the Solar Inverter. It also allows the Storage Inverter output to be in addition to the PV Inverter

  • Registered Users Posts: 7 theRed73

    I was planning on installing the PV inverter in the garage next to a sub consumer unit and run grid power & cat6 in ducts to the main CU.

    That would put the PV inverter in the same location as the batteries.

    The advantage of a separate storage as I understand it would be increasing my ceiling for charge from grid & discharge current to load.

    Any other advantages in having a battery string on a storage inverter? Monitoring, IFTTT, tweaking, etc?

    I'll likely run with just the PV inverter to get started. Just ordered 32x 200Ah from PWOD so distilling the shopping list from this discussion next...

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  • Registered Users Posts: 104 ✭✭runner2011

    I have a question that I'm hoping somebody can help me with , well kind of two questions. I had a Dyness a4800 4.8kw installed today and Waiting on the second one to be installed in about a week. The Solis inverter has a preselect for the Dyness Battery all good and working away. The battery parameters section are at what appears to be default or maybe they were set by the BMS? The Charge and discharge limitation setting are both at 50A .. the Dyness manual recommends 50A discharge .. it will do 75A (Max discharge power 3.6kw)and 100A for 15s .. should I set the two parameters to 100A / 75A / leave at 50A and will the BMS control it for the correct limits and duration? ..Secondly when the additional battery gets added ..whatever the correct charge and discharge parameters are will double..right? Thanks a mil.

  • Registered Users Posts: 5,744 ✭✭✭championc

    @runner2011 For the Dyness, the capacity will double, but charge and discharges RATES would be unchanged I would expect

    @theRed73 and ME3000 can only charge from the grid at a rate of 3kW, so it could be that a Hybrid may be able to charge at a higher rate. A separate Storage Inverter gives you a bit more control - like charging a car or heating water before a battery.

  • Registered Users Posts: 82 ✭✭Murt2

    Does anybody know of an electrical wholesaler that supplies Puredrive II 5kW batteries?

  • Registered Users Posts: 104 ✭✭runner2011

    Thanks for the reply .. Maybe I didn’t word it quite right .. if I have 2*50A batteries In parallel then the max draw could be 100A so where previously I could power a sustained ~2.5kw draw when 2 are connected it could be ~5kw rather than Solely a 2.5kw draw for twice the length of time ?

  • Registered Users Posts: 1,892 ✭✭✭SD_DRACULA

    If you have a Solis hybrid then yes (if you look at the spec sheet, it says it can charge/discharge up to 100a) but we were sold a bunch of BS and it can only sustain 5kwh for about 15 mins then drops to about 3.5kwh so yes you will get more than 2.5kwh but not double.

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  • Registered Users Posts: 104 ✭✭runner2011

    Thanks for the reply.. phew.. .. yup I get the peak output on the inverter and I’m ok with that as I knew about it when I bought it.

  • Registered Users Posts: 1,892 ✭✭✭SD_DRACULA

    The only way to maximize that would be to get two Sofar battery chargers in parallel, wire one battery to each and then you would get a constant 100a in theory (as long as the 50a can be sustained by the battery) but I doubt the financials make sense.

    Thought about this myself since with 4x dyness I can pull 200a max, and two sofars would get me constant 125a at least but it's easy to stay under the 5kwh in fact

  • Registered Users Posts: 104 ✭✭runner2011


  • Registered Users Posts: 7 theRed73

    Has anyone experience of the JK BMS? How does it compare to Seplos aside from the fact that Seplos can be daisy chained?

  • Registered Users Posts: 1,463 ✭✭✭poker--addict

    Guy up north with puredrive,5kw,2400£, collected.

    i wasn’t sure if that was a good price?

    This used to be a referral link 😎

  • Registered Users Posts: 19,462 ✭✭✭✭Muahahaha

    Was wondering with batteries can they be automated to charge up during night rates and then that power used during the day as needed? And can they both charge and discharge simultaneously, ie while it the battery is charging at night time can it also power the fridge freezer at the same time?

    Also (in theory) could you fill up a battery on night rates and then sell that power with the FiT at day rates? I saw an article about the FiT and most of the companies are paying around 17 cents per kwh, whereas my night rate is 0.095, can consumers make a profit or is there something preventing that.

  • Moderators, Home & Garden Moderators Posts: 4,461 Mod ✭✭✭✭graememk

    A battery can either charge or discharge not both. I can go into it more but the short answer is no.

    It can be automated but it's a bit DIY via home assistant/something

    Yes in theory you can buy on night and export during the day. But there's about a 20% round trip loss, also you would need to have a smart meter as your export isn't measured on the standard day night meter.

  • Registered Users Posts: 530 ✭✭✭chuck eastwood

    There was a guy on the fb group from the North about a month ago offering the same from the North. That's £2500 excluding delivery or fitting if I remember correctly. €2400 is probably about right if you can fit yourself

  • Registered Users Posts: 2,682 ✭✭✭yankinlk

    We really need to calculate what 5kw battery can expect to save in year. That price might be the "market rate" but does it even pay for itself over 10 years? Ie can u save 240 a year? I know it could last longer than 10 years... but some sort of benchmark to measure costs/value.

    Either FIT OR nightrate plus summer charging. Whatever is most....

  • Registered Users Posts: 20,170 ✭✭✭✭ELM327

    I've been binge watching his channel. A great source of information and he's quite easy to listen to, well spoken.

    I'm going to be looking for some dyness batteries in the near future. I've had 20kWh of them installed by the installer but I see from the spec sheets they can have up to 40 in parallel so I will be buying more! (and sussing out a victron quattro inverter too, to be the main inverter and relegate my current solis to a ac output of the quattro)

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  • Registered Users Posts: 2,224 ✭✭✭bullit_dodger

    I wrote a little app last year to calculate this stuff. Two different methods, but since it's better to export (with FIT) than it is to store in the battery, let's change "method 2" to 365 days charging.

    So about 8 years to payback a 5Kwhr battery costing €2400 with €0.28 day and €0.078 night rates. This is assuming you do this every single day. Fill up your battery at night and use those 5kwhr during the day. In reality you won't do that as I'm sure you will take vacations and not be in the house etc. so let's call it 10 years.

  • Registered Users Posts: 1 ddonq1412

    Have you got the file to I compare my saving before splashing out of massive battery.

  • Registered Users Posts: 2,224 ✭✭✭bullit_dodger

    I think we need more context? To whom was that directed to ddonq1412? What file etc?

    I'd be slow to go for a large battery though. Despite what I mentioned above, this was strictly a payback using night time during day rate scenario. It doesn't include FIT or anything. I think a small-medium battery is a good thing for a house (in general) but a massive battery would be something that I think people should think long and hard about unless going the DIY route, which while it isn't as hard as you might think, it's not for everyone

  • Registered Users Posts: 19,462 ✭✭✭✭Muahahaha

    Thanks, was thinking that it probably wouldnt be possible to power a house and also charge the battery at the same time so thats confirmed it.

    Out of interest is it possible to use an EV battery to power the house? I know from reading the forum that people rig up used Leaf batteries and do that. But is there a cable that allows power to go both ways, have a 24kwh Leaf sitting outside, fill it at night and then discharge the power to run the house over a 16 hour period during day rates. So in effect you are using the cars battery to kill two birds with the one stone instead of owning an EV battery and then another battery indoors for storage.

    If that were do-able it becomes interesting as I only use max 8kwh during January. Even with the 20% loss a 24kwh battery in a car could send 19kwh back to the house, Id use 8 and the remainder could be sold with the FiT at around 17c per kwh.

    Thanks for posting this, is your app available online somewhere? I had done calculations on my own usage which is low, 2,600kwh per year with a 71/29% split on day/night units. In peak winter Im using around 8kwh a day then in peak summer about 4kwh a day. Based on my current rates of 30c day and 9.5 cents night if I carried on as now the electricity would cost 629 euro a year whereas if I could move all usage to night rates it would be 248 a year so an annual saving of 381 euro. Which would give a 2,400 euro battery installation about about 6.3 years to return on investment. Then adding the 20% loss that gramemk spoke of above it would be more like 7.5 years and thats assuming all units purchased are night units.

  • Registered Users Posts: 2,224 ✭✭✭bullit_dodger

    Unfortunately my little app is integrated with my solar installation, so I'd have to decouple it to give it out. But one thing that you forgot in your calcs, is that you have to take care of the "depth of discharge". i.e. if you buy a 5Kwhr battery, you can't go from 100% to 0%, it's more like 100% to 10% if you want the battery to last. You won't kill it in 1 go if you did go from 100%->0%, but it's not good for it.

    So your "usable capacity" of a 5kwhr battery is about 4.5Kwhr. Some people recommend that you go from 100% - 20%, so your usable capacity is only 4Kwhr, but I think it's ok to "push it" a little. Hence your break even point is something longer than you have.

    Course, this assumes stable rates, in reality we'll (probably) have €0.30+ rates maybe even as much as €0.40 in the future, especially likely for the 2-3 hrs of peak usage when we are all on smart meters.

    Everyone is different though. For me, it's wasn't completely about a "break even" point in time. I had the money last year and now, going forward, those winter bills won't sting as much as I can make them €80-90 every 2 months lighter with my 8Kwhr battery by "load shifting" them to night rate.

  • Moderators, Home & Garden Moderators Posts: 4,461 Mod ✭✭✭✭graememk

    What your talking about is vehicle to grid (V2G) It exists, and worked on the leaf but there has been nothing since. (and the charge point to support it was something like 2-3k and not certified for ireland either.

    As for cycling any battery for a FIT, Its not worth it, Load shifting does save money though (charge up on night rate and discharge on day)

    And for a measured FIT you need a smart meter, Just looked up energia's smart meter rates (the higher rates thats coming in Oct) and they are

    43.21 day

    24.67 night

    45.27 peak.

    18c/kwh doesnt sound too great any more.

  • Registered Users Posts: 19,462 ✭✭✭✭Muahahaha

    @bullit_dodger thanks for the comments on the usable battery, I hadnt considered that

    @graememk you're right I hadnt considered the higher rates of these smart tariffs and 24 cents for a night unit is eye watering. Did I read something before though on here that you can get an exemption from a smart meter but still get the FiT by reading your own meter? Or will an energy company just not give you the FiT unless you install a smart meter? Given the prices of smart tariffs Im determined to avoid having one until they become mandatory.

    And obviously running the house on battery power from a car is a non goer if the charger alone would cost 2-3k and not even be certified which Id guess might then invalidate my house insurance in the event of a fire. Its a pity though as Im a low user of both the car and electricity so if a reasonably priced solution did come along that was safe and certified then it would be an interesting option. But ultimately it would be scuppered by being forced on to much higher smart tariffs compared to the tariff Im on now (30c//9.5c)

  • Moderators, Home & Garden Moderators Posts: 4,461 Mod ✭✭✭✭graememk

    If your on a Day/Night meter, you get an "estimated" FIT depending on what size your solar inverter is. The day night meters do not measure export.

  • Registered Users Posts: 1,519 ✭✭✭THE ALM

    Took longer than expected but finally collected the batteries on Thursday.

    All intact and well packaged.

    Checked charge and cell levels on the internal BMS, no need to hook up anything at this stage as all can be checked on the integrated menu/screen.

    Getting these up a stira attic staircase is a pig of a job, get help as they are heavy at 48kg. My impatience got the better of my and I decided to manhandle two up myself!!!!!health and safety would have had a field day🤔 thought my weight and battery combined would have gone through a tread...

    Powered down the inverter and hooked everything up before powering back up. Selected User Defined battery type and inputted the parameters provided, saved, exited and all was good. Battery level on the Solis tallied with that shown on the internal BMS. Have been told that a future Solis firmware will have the battery type pre-defined.

    Charging and discharging looking good so will run for the weekend before tidying everything up and securing the batteries in there final position.

    Although I ordered all the cables I forgot to specify an amphenol surlock connector on one end of the cable for connecting to the Solis. Managed to get a set of cables from an electrical wholesaler and have ordered the surlock connector for the cables I have.

    Post edited by THE ALM on

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  • Registered Users Posts: 307 ✭✭redmagic68

    Can the inverter be set up to charge the battery on solar during the day when the array is producing then discharge in the evening when the sun is gone before night rate time comes, then charge on night rate, simply through a sofar inverter? Then manually setting it not to charge on night rate during a really good sunny spell and have it discharge at night as required?

    I don’t have the expertise for automation yet.

    I was also wondering what is the best way to go about monitoring and controlling everything down the road and what to buy.

    currently I have an eco eye energy monitor in the meter cabinet outside the house on the detached garage as I didn’t have an available mains wire internally but the rccb board is in the house and the inverter and batteries will be in the same utility room as it once installed. I’d like to set the system to use the battery as described and then down the road when we get an EV and charging box to incorporate it and hopefully some automation at that point. an eddi isn’t on the cards currently as we have solar thermal. I’m guessing it’s likely to be supplied with an app similar to what’s shown in this thread also?

    8.4 kwp east/west Louth,6kw sofar, 9.6kwh batt