@editor Hi, that's correct I already had solar 5.4 kw array. Had it just over 3 years now.

At the time got the Eddi Water Diverter and Zappi car charger. Along with 3x Plyontech 2000 batteries. 2.5kwh storage, set discharge down to 20%

One of my Plyontech batteries had actually gone faulty last few months currently waiting for my replacement to arrive. Have sold off other two batteries, new replacement. will help fund what is basically 3x storage what I had previously. With the Fogstar being 15.5Kwh. LFP meaning I can take down to 0%

Even if I did not have solar at this price think its no brainer to just get battery system buy your electric at night. 

Have done second brief video or my system running 

if only i wasnt about 10 months ahead - i would have two of them instead of building my two Seplos cases, i really like the look and design features that they have incorporated into it.  

@misterb I guess you never know what the future holds. Can only make decision on the information that you had at the time. Did look at the Seplos cases, but it does not make any sense with how things have changed. With this Forstar battery being such great value. You may have wait for one come back in stock.

@adrianmc i am part way through assembling my second Seplos (just finishing the top balancing), i will have 28.6kw when its finished, so i wont be looking to add any more!

its the 'early adopter' curse, i actually started out and bought just the cells for my first battery initially, intending to build my own battery box from scratch, then the Seplos case came on the market and i got one of the first ones in the UK, so i am not really complaining. There are probably hundreds of UK battery builders who trod the path long before i even thought about it, we all owe them a debt of gratitude in my opinion, as they were truly the early adopters.

i knew about the Fogstar 'own' design and was tempted to sell my original Seplos (10 months old) and instead of another Seplos, buy two of the new Fogstar batteries, but i was unsure re compatability, so went for what i knew. i will now be able to power my home for at least 10 months of the year on the cheapest overnight rate i can get, currently Intelligent Octopus Go (as we bought a PHEV recently, but we needed a new car anyway, though we could have got a cheaper one and still gone onto IOG)

i have actually learnt a lot by going down the self build/self assembly route, though im not sure how useful it is ever going to be LOL.

i had a lot of help on this forum when i set off on the journey, especially with initial teething problems with my original Sofar inverter. 

Best wishes going forward, PS, there are a lot of people who would recommend that you shouldnt take the battery down to 0% or charge up to 100% f you want to extend its longevity - i dont know by how much the life of the cells will be extended, if at all, but i keep mine at max 10% discharge and 90% charge currently. i know thats 20% below capacity, but with around 23kw, i will have enough for most days of the year. 

So life got in the way, as it normally does - I have eventually got onto it and installed it - following regs as best i can.

MCB

Surge protector

AC isolator

Cabling & trunking

DC cables need to be contained - TBD

Fired up over weekend... 

+ Battery was easy to start and get the BMS connected - Data on Sunsynk quickly, overnight timed charge was steady and worked fine, charged to 90%, as instructed.

- I am struggling to get the inverter to discharge the battery, suspect the CT is wired wrong way round as the arrow is correct direction on grid supply, will take a further look tonight. Is there an optimum UK settings for the unit? the manual isn't clear. Perhaps I need to visit a Sunsynk forum.

@ggw I think the cable to the unit needs to be double insulated if you can touch it.

Ideally the twisted pair from the CT should be away from any mains cables, as the signals picked up make it hard for the sunsynk to null the home overall power.  It won’t stop it from working though.

We have a 280L Seplos mason and sunsynk, which is not so different I think.  The Seplos case must be earthed, I expect yours too.  The batt + and - might be only 50V apart, but they have a huge AC component, and mustn’t connect to chassis.  Our bms data is dodgy without that earth.

setting up the sunsynk is NOT obvious, despite what the sales guy says repeatedly.  I would love a flow diagram to go from the settings to actually what happens.

Earth cable connects to the top right hand corner of the battery. 

Fair play to you getting it in the wall. 

How low will you get the battery discharge ?

As it's LFP in theory I believe can go to 0% have mine go to 5%

The weather has changed this week more day light battery well topped up each day. At moment I am allowing mine to charge for 2 hours overnight just for that boost for the morning so won't be pulling from the grid. Alot more usable usable battery compared to what I had 

Pleased so far. 

@robl 

And as everyone said and expected, the CT cabling was the wrong way round. The manual is awful in that section, basically guess the colour to pin scenario

Anyway, battery discharging, house running on battery for first time. That sweet Economy7 rate...

Until solar...

@adrianmc 

Ive it setup 90% ~ 10% - to match the 80% DOD rate that is listed in the Fogstar manual.

We charged our 15.5kWh 280L system to 56V in AGM V mode (3.5V per cell) over the coldest months with Octopus Go, which is 100% or near enough.  That was enough for all but a few days for our use, which is higher then as our heating is gshp and there’s little out of our PV.  Note that even if you use Li mode, the voltage in AGM V should be defined.

The sunsynk and Seplos battery didn’t agree on SOC initially, so attempting to charge based on SOC was very confusing back then.  It used to sit at 100%, still charging for hours(worrying!).  Now it’s stabilised, I think both systems adapt their idea about how many Ah the batts are as they count coulombs - the batts are 304Ah, Seplos says 330Ah, and sunsynk says 425Ah !  (The bms is linked to sunsynk fine, I can see the bms data on the sunsynk batt screen.)

It’s simpler to use now, and sunsynk is set to charge to 90%, typically falls to 60% these days.  There’s no reason for us to reduce below 90% overnight charge; sometimes we export a bit of solar, sometimes not - financially similar with Octopus, and likely better for the grid for us to time shift.

@robl did you top balance all the cells before installing the battery ?