Home attached battery storage solution

unkel · 21-02-2019 3:38pm #1

Looking to install a battery home storage solution in the next few months to work with my 3.8kwp solar PV install. I already have a solar thermal hot water heating system and the family car is an EV

I've decided on an AC coupled system. I'm thinking of this AC inverter:

SoFar ME 3000SP

datasheet

It's basically an AC coupled inverter that you attach a 48V battery to. The inverter will sense if you produce more PV than you use in the house and will store the difference in the battery. And if you use more electricity in the house than you produce, it will use electricity from the battery instead of from the grid

Both ways to a max of 3kW

As a battery you could go the neater but more expensive li-ion route with say a Pylontech 2.4kWh battery. Both together here for sale for GBP1299 + VAT

Linky

Or you could just pick up the inverter for about EUR700 and then some used lead acid deep cycle leasure batteries second hand cheaply

If you get this work done by an SEAI installer, you are entitled to €1000 subsidy. Or you could DIY with the help of a friendly electrician (and not get the subsidy)

Any of you planning to do this? Any tips / opinions? If there are any SEAI installers here, you can PM me with a quote!

unkel · 21-02-2019 4:02pm

And maybe I should have stated the obvious: I would like this done as cheaply as possible. The aim is to have a pay back period as short as can be done, while future proofing the system. I could easily replace the lead acid batteries with a 10kWh li-ion pack in a few years time when they come down in prices. I reckon if I do a DIY install with say 4 * 120Ah lead acid batteries (giving about 6kWh of which maybe 4kWh is usable) for not much more than a grand in parts

If I could then self use say 60% of my annual PV generation of 3800kWh, instead of maybe just 20%* without a battery (is this a reasonable assumption?), I would save 3800 * 40% * 18c = €275 per year, or a pay back time of around 4 years.

*this 20% is a very low figure. It implies that 80% of my solar production is going back to the grid for free. I do feel it is going to be quite realistic though, unless you spend your life switching on appliances during the day while the sun is out, pluggin in your car to charge during the day, etc.

Gumbo · 21-02-2019 7:16pm

Interested.

Does the current invertor need to be a specific spec to allow battery storage?
I know I have a trannergy invertor.

unkel · 21-02-2019 8:13pm

If you have solar PV already you have 2 options:

-change your solar inverter for a hybrid solar inverter. These are not cheap though. You're talking about €1200 + VAT for one retail :eek: You recoup some money by selling your old one. But you're not the only one with this plan and simple inverters can be picked up cheaply now. The batteries attach directly to the hybrid inverter. I call this a DC side install. Benefits: less hardware, simpler install

-keep your inverter. But then you will need a battery inverter like the SoFar I linked to above. The batteries attach directly to the battery inverter. I call this an AC side install. Benefits: cheaper, more versatile and you can charge your batteries with night rate (as well as solar), this AC side works completely independently of your solar system

Coltrane · 21-02-2019 8:37pm

Unkel, your assumed self-consumption is reasonable, assuming your heating system is not electric. (Mine is an air-to-water, and I'm at 67% self-consumption over the last 12 months, using my 5.2kWp array in Dublin...we also have an electric range oven, and UFH, as our 'batteries'...we even charge our EV using a Zappi/solar surplus...still the prospect of a battery to soak up the remainder is very tempting...).

Thanks for the link. The SoFar batteries are surprisingly cheap, very much cheaper than quotes I've had for Sonnen products.

Let us know if you have any interesting SEAI-installer contacts!

Roll on the day when we can V2H our cars! Mine is CCS and there seems to be little prospect within its lifetime of using it as our battery.

unkel · 21-02-2019 8:52pm

Welcome to boards.ie Coltrane, nice first post!

V2H is still years away from being affordable unless you have a CHAdeMO EV and your utility provider is installing all the hardware for free as part of at trial

My own car is CCS too. I thought of replacing my dumb EVSE with a smart one, like a Zappi, but they are very expensive for what they are and of limited use, even if your car is usually parked at home during the better solar hours.

My house is old skool, so I have gas heating and gas hot water (well mostly solar), no electric heating and no electric showers. Electricity use is about 3.5MWh / year for normal household use excluding EV

As for costs, it does matter. You can install everything Sonnen and Tesla and it will look good, but the payback time will be longer than the life of the hardware. Those systems cost you money, not save you money. That doesn't work for me. Saving the planet shouldn't have to cost the world

Coltrane · 21-02-2019 10:25pm

Another possibility for you, Unkel, could be to invest in an electric space heater. These can be set to switch on only with surplus solar. Good for bright but chilly days. I use a far infra-red 400w free standing unit in the kitchen with a Smappee smart plug. Fairly low cost and probably less depreciative than any newish battery.( But you’re thinking of old lead acids!)

You could of course go the whole hog and buy a heat pump - that’d soak up your solar surplus!

unkel · 21-02-2019 10:47pm

I already have two large electric space heaters - crypto mining rigs

and they'll be running for another few months usefully (heating up the house) and basically as long as I don't have a battery solution in place. I should be running these from 10AM until 5PM and then on night rate from 11PM until 8AM (so I don't run them fully on full day rate electricity from the grid), but I'm not bothered with that.

Smart cheap electric space heaters, that's interesting. Does the Smappee smart plug work directly with a CT clamp or what way is that setup using solar surplus?

I know nothing about heat pumps, but my house was built in 2000 and has very poor air tightness, I don't think it would be suitable. Also my gas boiler is an excellent 98% efficient Viessman and was only installed 6 years ago. Leaving that well alone.

Space heating with excess electricity is only useful in winter though and in summer I make the most electricity...

rolion · 21-02-2019 10:49pm

Keep your hard earned cash in your pocket and buy something nice to your wife ,guys !
Batteries are not for us,normal home owners,green willies saving the planet.
Not today...

Surplus for a good PV system ... i wanna see that being used for a heat pump or space heater when needed in the winter.
Your system barely warms up the bumble bees looking for something warm to their cold arse...or plan to use the surplus of PV in the summer for what !??

Good luck and do please share here your adventure....i'll do mine in couple of years,no offence.

unkel · 21-02-2019 11:06pm

rolion wrote: »

Keep your hard earned cash in your pocket and buy something nice to your wife ,guys !

Says the man who bought a EUR1500 ABB inverter

My Solis 3.6kW dual MPPT inverter set me back GBP220 brand new including shipping. And I have made a profit selling on all my previous solar equipment for more than I got it for

Picking up a few EUR50 deep cycle 100Ah leisure batteries tomorrow to have a play with. Four of these would give me a 5kWh battery for EUR200 (plus cost of cabling / clamps)

rolion · 21-02-2019 11:16pm

@unkel

Do you have access to my fcuking bank account that you know how much i fcuking paid for it !!!??
Second,when i bought my ABB years ago,you didnt even knew about PVs ...AND ... ABB was the only one inverter certified by ESB to work on their grid. I am more than happy with the system,best in class, industrial graded equipment,it did 9MWh,9,000KWh,9.000.000 units since day one.

So please back off with your silly, childish accusations.Dont getting me fcuking started...please...

I'm in for longer,i am waiting for others to buy expensive "ABBs" so that i can use that shared expeience and get a proper one...
My LEAF is "saving" every drop of their cells, waiting to come in the house...my eNV200 40KW once is writen down as business expense,same coming up in the house. that's almost 60KW and few hundreds of Ahsss...

Be good and take care,enjoy the PVs and EUR50 DC batteries ...buying ,selling and trade-up on other's pockets

PS

Found another picture of warming the invertor,the ABB one ... even bees loves it !
Dedicated for you...

Coltrane · 21-02-2019 11:29pm

Unkel, yes Smappee measures consumption and production using CT clamps. Its control box can send programmable on/off signals to the smart plugs (max 3kW load, too small for your rigs), so for example I’ve mine set to turn on my 400w heater when there’s a 450w or greater surplus and back off again as soon as the surplus disappears.

unkel · 22-02-2019 12:00am

My rigs are a touch over 1kW each, so not as big as you thought. And I could scale them down from 2 to 3 smaller rigs or even take out a few GPUs and sell them on. Don't want to switch the rigs on / off all the time though, it takes a good few minutes for them to boot up, connect to a mining pool, load the DAG files for each GPU, start mining and spool up to the max hash rates.

Any link to where you bought your Smappee system? Interesing stuff all the same!

rolion · 22-02-2019 12:20am

@unkel
you want some FREE of CHARGE batteries !?
See attached...just broke them down today from a 1,500VA ups.
PDF data specs atatched too.
save the eur50 !

unkel · 22-02-2019 12:58am

They seem to be 6V, 7Ah. So You'd need 125 of them for a 5kWh setup, would cost you a grand in cabling alone and a good few days to hook them all up. Or am I missing something here?

Thanks for your kind offer anyway

Coltrane · 22-02-2019 8:35am

unkel wrote: »

My rigs are a touch over 1kW each, so not as big as you thought. And I could scale them down from 2 to 3 smaller rigs or even take out a few GPUs and sell them on. Don't want to switch the rigs on / off all the time though, it takes a good few minutes for them to boot up, connect to a mining pool, load the DAG files for each GPU, start mining and spool up to the max hash rates.

Any link to where you bought your Smappee system? Interesing stuff all the same!

Boards won’t let me post an url, as a new user, Unkel.

Check smappee.com

unkel · 22-02-2019 11:33am

Looks like a cool piece of kit. The cheapest it has been for sale on Amazon is GBP150. That's a bit rich for me. I just picked up an Owl intuition monitor on eBay for GBP7 including shipping. It is complete with clamp with wireless transmitter (that you can connect in your outside ESB box) and wireless monitor that you can place anywhere in your house. Now this can only measure and display, not control a smart plug like the Smappee.

22-02-2019 7:40pm

unkel wrote: »

would cost you a grand in cabling alone and a good few days to hook them all up. Or am I missing something here?

Millions of teeny cells? Good enough for Neo-Tesla and all the wannabes ...:rolleyes:

unkel · 18-03-2019 12:19am

Sent an email to all the SEAI approved PV installers for a quote for either AC or DC coupled storage. Most of them didn't even bother replying :rolleyes:

A few rang me / emailed me back but seemed to be very confused about the idea of AC coupled storage. When I mentioned the Tesla Powerwall (also an AC coupled storage system) they kind of had heard about that alright

One came out to have a look at my current system. I wasn't very impressed with him either. He said he would prepare a quote for a DC coupled storage system, but I never heard back from him

Only one company did engage in a meaningful email exchange. They did impress me, knew the SEAI requirements inside and out (although he didn't agree with them), and he not only gave me a detailed quote for a DC coupled storage system, but it was also a very reasonable quote, with not a huge mark up on the parts. Can I mention his company here or is that still against the forum's rules?

Because hybrid inverters are still very expensive, the net cost to me after the grant would still have been over €2k. I can not justify that, so I did not go ahead. I did pick up a Sofar inverter almost new for very reasonable money in the UK today (it's on its way to me) and I'm now contemplating to go for a cheap 5kWh lead acid 48V battery setup (EUR200), or just to bite the bullet and get a Pylontech lithium battery...

unkel · 18-03-2019 9:03pm

Got approval from the mods to mention the company above:

It was Zoltan Nemeth

zoltan@savememoney.ie

From savememoney wind & solar

website

rolion · 19-03-2019 1:30am

@unkel

I'll go back through all your past posts where you did the maths and arrived to a single conclusion: battery not worth the investment "today".
What's been changed,i wonder !?

Good luck !

Muahahaha · 19-03-2019 1:42am

Coltrane wrote: »

Another possibility for you, Unkel, could be to invest in an electric space heater. These can be set to switch on only with surplus solar. Good for bright but chilly days. I use a far infra-red 400w free standing unit in the kitchen with a Smappee smart plug. Fairly low cost and probably less depreciative than any newish battery.( But you’re thinking of old lead acids!)

You could of course go the whole hog and buy a heat pump - that’d soak up your solar surplus!

Can I ask would you recommend infra red heaters? Do they take long to heat up a space from cold and also what brand and you using?

unkel · 19-03-2019 1:50am

rolion wrote: »

@unkel

I'll go back through all your past posts where you did the maths and arrived to a single conclusion: battery not worth the investment "today".
What's been changed,i wonder !?

Good luck !

I don't think I have ever made a generic statement like that, rolion. I like renewables and I feel we all need to do a lot more to reduce the use of fossil fuels and to reduce harmful emissions. But not at any cost. Fair play if you don't mind spending thousands on equipment that will be end of life many years before they have paid for themselves, but I couldn't justify that to the accountant in me. Using generous grants can help sometimes, but not enough in this case. Buying hardware at well under half of the normal selling price and doing a DIY install is more up my street though

rolion · 19-03-2019 10:53am

unkel wrote: »

I don't think I have ever made a generic statement like that, rolion. I like renewables and I feel we all need to do a lot more to reduce the use of fossil fuels and to reduce harmful emissions. But not at any cost. Fair play if you don't mind spending thousands on equipment that will be end of life many years before they have paid for themselves, but I couldn't justify that to the accountant in me. Using generous grants can help sometimes, but not enough in this case. Buying hardware at well under half of the normal selling price and doing a DIY install is more up my street though

Agree to disagree...in a most respectul way.

"The grid is the most effective battery" ... "dont buy solar diverter,send all extra excess PV energy to grid" , quote closed.

Whats changed ? YESTERDAY,with a small array,you were confident, a bit pissed off when you have a big array TODAY and see how the moneys goes for free TOMORROW to mr grid ? Welcome to my world...

Put up some figures about the battery storage.
From scratch,with inverter and all the auxiliary circuits.
Cabling and installation.
Without any grants,not worth it,in my humble opinion.Not even for the environment.

Oh,we miss Conor with his lovely graphs...

Just to add .. .you sound a nice bloke...can i advise you in a friendly way: do not buy second hand battery storage equipment,inverters or anything to do with it...your life and your family could be at risk.
It happened at bigger houses,big corporates...do not mess with those powerfull chemicals...see what a fcuking phone can do yo your fingers (apart of bringing lots of dirty cash from the compensation,but thats another side of the story).
Stay safe.

unkel · 19-03-2019 4:44pm

rolion wrote: »

"The grid is the most effective battery" ... "dont buy solar diverter,send all extra excess PV energy to grid" , quote closed.

In a lot of cases it's cheaper to let surplus go to the grid for free rather than charge up a battery / heat some water with it

rolion wrote: »

Put up some figures about the battery storage.
From scratch,with inverter and all the auxiliary circuits.
Cabling and installation.
Without any grants,not worth it,in my humble opinion.Not even for the environment.

The price for a basic AC attached battery system with a Li battery is about the same with the grant (installed by an SEAI approved installer) as it is to do DIY and buy the parts yourself

In both cases the payback time would be quite long. Too long for me. So I agree it's not worth it. However if you go for a second hand inverter and lead acid batteries, the payback time can go down to a couple of years if you buy well. And don't worry, all my equipment is installed outdoors on the outside wall of my house nowhere near any inflammable material

niallers1 · 22-03-2019 2:46pm

rolion wrote: »

Batteries are not for us,normal home owners,green willies saving the planet.
Not today...

I disagree, since Mid September I've only given back about 31kwh to the grid thanks in part to my 2x2.4kwh pylontech batteries (and my east west array)

I would have given away free alot of kwh without the batteries.

Electricity prices have gone up again in March and will probably continue to do so for the next few years. That should be factored into the calculation.

unkel · 22-03-2019 2:57pm

If there is a way of measuring how many kWh were released by the battery at what times, then you can calculate savings at day or night rates, so you have a fairly accurate way of calculating the pay back period. But even with the subsidy, the additional cost of the hybrid inverter and 2 pylontech batteries is substantial. I doubt the pay back is less than 10 years, probably a good bit more.

Hopefully the batteries will last a lot longer than that, the latter is looking quite hopeful if the SOC higher and lower levels were set conservatively. Any idea what they were set at? Any idea what the max charge and discharge rates were set at?

niallers1 · 22-03-2019 3:01pm

unkel wrote: »

Hopefully the batteries will last a lot longer than that, the latter is looking quite hopeful if the SOC higher and lower levels were set conservatively. Any idea what they were set at? Any idea what the max charge and discharge rates were set at?

lower level is 10% not sure what the max charge is but I think it's 100%. I'll try check that.
The max discharge is 2.4kw and the max charge is probabaly the same up to a certain percentage SOC .

I'm ok with the payback time being around 10 years. My goal is to reduce my monthly outgoings as much as possible for when I'm older or if I lose my job down the road , having lower bills apeals to me.
I paid for the installation with the cash back I got for switching my mortgage. That was fairly painless and the easiest few grand you'll ever make.:)

unkel · 22-03-2019 4:02pm

niallers1 wrote: »

I'm ok with the payback time being around 10 years. My goal is to reduce my monthly outgoings as much as possible for when I'm older

Yep I'm the same myself. My savings are doing nothing for me and over the few shekels per year they generate on my savings account, I have to pay tax.

I'd rather invest it in something that will give me (some) return in the form of reduced outgoings (and helps the environment). That's why I have an EV, solar thermal and solar PV.

I also like the idea of producing at least as much electricity as I consume per year, from my own renewable source.

And backup. Here in Dublin we never really have power outages, but in case it happened, you could run your house essentials on it for several days, provided your battery was at least about half full

Being self-sufficient also shields you to some extent from the price and tax increases, excises and all sorts of other levies that no doubt will come in future

rolion · 08-04-2019 10:21am

@unkel

Well,any news !?

Got a good offer of Leaf 24KW battery pack for less than €3,000 collected and still cant make up the numbers to buy it.

unkel · 08-04-2019 1:58pm

rolion wrote: »

Got a good offer of Leaf 24KW battery pack for less than €3,000 collected and still cant make up the numbers to buy it.

Not a bad price, but still a huge amount of money for something that might save you just a few hundred quid a year.

rolion wrote: »

@unkel

Well,any news !?

Got the AC battery inverter for a very good price nearly new from the UK - was used by a regular poster on a renewables forum over there who has massive systems in place because he was upgrading to a higher output one. I mounted it, have all the other parts required but it's not yet wired up. Been busy and bad weather. Hoping to get my hands on a cheap battery in the next few weeks.

rolion · 08-04-2019 10:32pm

So,to close it ... batteries for ongriders not financially viable as TCO and RoI. Today.
Tomorrow,maybe.

unkel · 08-04-2019 11:55pm

rolion wrote: »

batteries for ongriders not financially viable as TCO and RoI. Today.

Everything is financially viable as long as you buy the parts very cheaply and install DIY (or with the free help of a friendly sparks). Preferably so cheap that if you decide to dismantle it and sell the parts on at a later stage, you get back more than you paid for it. Negative ROI :cool:

But yeah, if you already have a solar system then an SEAI approved and granted upgrade to have a lithium battery attached has a very long ROI. Even if you get it done for very reasonable money, like the quote I got from Zoltan in savememoney wind & solar...

Since when did you start caring about ROI anyway? :pac:

rolion · 09-04-2019 8:46am

Thanks.
Got your subtle sarcasm...

I will love to see you doing a breakdown of the storage, new or second hand(as promoted by you).
Same as with the 4c gas boiler (despite knowing absolutely nothing about boiler modulation).

Can we have a figure for batteries,for inverter,for cables and for installation.
Also,final figures with a 24h and with a day/night rates meter.
You can use Zoltans quote no problem.I don't know him,no offence.

Let's see what kind of games are we playing here as I reached the conclusion that ongrid bats are hard to justify.

Thanks in advance.

niallers1 · 09-04-2019 9:03am

rolion wrote: »

Thanks.
You can use Zoltans quote no problem.I don't know him,no offence.

Zoltan installed mine last September.
4.2kw Solar PV with 4.8kwh Pylontech battery.
Very happy so far.

Now that I have it for almost 7 months the only thing I would have done different would have been to get a diverter. In the past 3 weeks I've given away about 60kwh to the grid (wasn't expecting to give away anything in March) and we still have another 6 months of long days ahead.
April to September will be giving away alot more. Could be giving away 200kwh in June the days are so long.

09-04-2019 12:34pm

unkel wrote: »

Got the AC battery inverter

Batteries are DC. Just because the government can't get their terminology right doesn't mean we have to reiterate.
Your inverter is a flavour of AC Coupling.

....next we'll be rating them in mAh like phone cells just to sound bigger...:rolleyes:

I bought a LiFePO4.

The only reason I went for such li-ion is because I will have to lift it.
I still maintain FLA is King of Static Applications.

I'm building my own BMS because I've noticed everything off the shelf is proprietary/not very good/not versatile.
The level of safety required for this is pretty staggering and quite expensive....Lead is so much simplier.

The thing about 24kWh leaf batteries is they are available to the market as they were replaced from a car due to capacity degradation.
The 24kWh battery is undersized for the vehicle load and will have had a very hard life. I would speculatively derate it to 70% capacity when applying it to any cost per kWh formulae and reduce it's energy density accordingly.

unkel · 09-04-2019 3:04pm

rolion wrote: »

Can we have a figure for batteries,for inverter,for cables and for installation.

batteries => hopefully free or far below market value

Inverter => GBP400 incl shipping

cables + disconnects + fuse + outside socket + RCBO + other bits => a lot of them free, but spent about €100 in total myself

installation => free (done by me and RECI neighbour)

Total cost of the system €560 - €700 depending on the batteries

I should be easily able to dismantle the system at any point over the next few years and sell the parts for what I paid for them. Or in other words a negative ROI

n97 mini · 09-04-2019 3:29pm

unkel wrote: »

sell the parts for what I paid for them. Or in other words a negative ROI

That's positive ROI!

unkel · 09-04-2019 3:40pm

That's semantics

A 10 year ROI is a positive number, a minus 1 year ROI is a negative number. But I'm sure we mean the same thing!

rolion wrote: »

I reached the conclusion that ongrid bats are hard to justify.

I agree with you, I couldn't justify a battery system installed under the SEAI grant, even if you can get it done for a very reasonable price. And that's not even taking into consideration that we might one day get a FIT (I believe it when I see it)

But a system that doesn't cost anything but will save you money from day one is of course fully justified

bunderoon · 18-05-2019 9:32am

Hey all,

Following this thread with interest.

I have no renewables at present but aim to get some sort of system up and going sometime in the future.

House is south west facing with 2 acres of land. 20' shipping container (soon to be converted into an office / storage) about 30 meters behind the house but facing south.

I work in a place where I will have access to a hundred or more 18650 cells (that are in laptop batteries)

I am thinking about Solar PV setup and a DIY battery bank.
I've been watching this guy for the last few months:
https://www.youtube.com/watch?v=L7cZj0u-Z2Q

and he has recently showed new stacking modules for the batteries (scalability) - https://kit.com/jehu/jehu-s-diy-powerwall-pcb-project

Since the batteries will be free, a 5-6Kwh battery system would cost me about 600 - 700 US dollars.
https://www.paypal.com/webapps/shoppingcart?flowlogging_id=9055e71a6fc76&mfid=1558168140832_9055e71a6fc76#/checkout/openButton

For safety, I would store the battery and inverter in the shipping container.
I have built small 18650 battery packs with BMS in the past so I think I can manage this build.

Anyone have experience with this kind of DIY route?

unkel · 18-05-2019 12:39pm

Jehu is a nice guy with cool videos (I follow him too) and even if your DIY skills are fairly low (like mine) and you have access to free 18650s, then his stacked kits make sense. I would do it! Do take into account that everything you bring in from the US is liable to at least 23% VAT and admin charges, possibly also import duties

To compare a 2.4kWh commercially available lifepo4 battery like a Pylontech would cost you the guts of €1000, so a system twice that size for half the money looks like a good opportunity to me

You could of course start relatively small, with solar panels on your new office, a solar charge controller, a lifepo4 DIY battery bank and a suitable power inverter to create an off grid system for your office

Best of luck and keep us updated!

18-05-2019 2:40pm

Why would you spend a fortune in testgear and years of your time soldering used cells the size of your thumb together when you can just buy some you can assemble in 30minutes?
Lifepo? Are the weight restrictions of the endeavour that prohibitive you can't recommend a less expensive less volatile alternative?

bunderoon · 18-05-2019 3:21pm

unkel wrote: »

Jehu is a nice guy with cool videos (I follow him too) and even if your DIY skills are fairly low (like mine) and you have access to free 18650s, then his stacked kits make sense. I would do it! Do take into account that everything you bring in from the US is liable to at least 23% VAT and admin charges, possibly also import duties

To compare a 2.4kWh commercially available lifepo4 battery like a Pylontech would cost you the guts of €1000, so a system twice that size for half the money looks like a good opportunity to me

You could of course start relatively small, with solar panels on your new office, a solar charge controller, a lifepo4 DIY battery bank and a suitable power inverter to create an off grid system for your office

Best of luck and keep us updated!

Thanks Unkel.
Once I get more info and in a better place to start, I'll start a thread here and document it.

bunderoon · 18-05-2019 3:49pm

Sir Liamalot wrote: »

Why would you spend a fortune in testgear and years of your time soldering used cells the size of your thumb together when you can just buy some you can assemble in 30minutes?
Lifepo? Are the weight restrictions of the endeavour that prohibitive you can't recommend a less expensive less volatile alternative?

Fair point and I'd be the first to do that.
The modules themselves do need some soldering but not each cell. Each cell just slots into a spring loaded enclosure. Granted, there will be testing of each cell to weed out the bad ones and also pair the capacities somewhat.

Just to be clear, it's a €1200 lipo (2.2Kw) vrs a €300 (2.4Kw) equivalent - 35 modules that I can add to as I go instead of spending another €1200 to add to the first lipo.

The 18650 modules (fully populated) arent going to be that heavy. Whatever battery solution I'll go for will be placed safely away from the house in the shipping container.

While I'm on this point of PV, my main aim is to provide hot water, then afterwards; power in the evenings for certain appliances in the house when we get home via battery. I've a 300Ltr hot water cylinder and was thinking of removing the 3Kw immersion element and replacing with either a 1Kw or 1.5Kw element. Once the temp is up in the cylinder, its only a matter of keeping it there. I can see this happening during the daytime. Once at temp, the batteries start charging. The money I save on the batteries will go a way to pay for the other bits.

niallers1 · 19-05-2019 2:32pm

bunderoon wrote: »

While I'm on this point of PV, my main aim is to provide hot water, then. I've a 300Ltr hot water cylinder and was thinking of removing the 3Kw immersion element and replacing with either a 1Kw or 1.5Kw element..

No need to change the element in the tank. Surplus will trickle feed up to 3kw. Doesn't mean it will draw 3kw unless of course you boost the heating . Then it will look for 3kw.

decp · 20-05-2019 3:43pm

What is involved with installing a trickle feed for an immersion heater?

(Have 900w solar, 2k inverter, 2.4k battery)

n97 mini · 20-05-2019 4:35pm

decp wrote: »

What is involved with installing a trickle feed for an immersion heater?

(Have 900w solar, 2k inverter, 2.4k battery)

Google solar diverter. They adjust the power to the immersion based on the surplus solar power.

Also look at the prices and work out the payback time. For some it's in excess of 20 years.

rolion · 20-05-2019 4:40pm

decp wrote: »

What is involved with installing a trickle feed for an immersion heater?

(Have 900w solar, 2k inverter, 2.4k battery)

Without sarcasm ,i will say add more solar panels.
You will need a minimum decent of 2-3Kw to justify working parameters and financial figures of a diverter.

decp · 21-05-2019 8:40am

Adding another 3k of panels is the plan, no panels on the house yet. I built a Jehu battery from his PCB kits. Added BMS-Battery shutoff for over/under power & temp. So all this lives in the shed.

The immersion is interesting, I have a micro grid tie (panel mount) inverter that I wanted to use for heating water.

bunderoon · 21-05-2019 1:08pm

decp wrote: »

Adding another 3k of panels is the plan, no panels on the house yet. I built a Jehu battery from his PCB kits. Added BMS-Battery shutoff for over/under power & temp. So all this lives in the shed.

The immersion is interesting, I have a micro grid tie (panel mount) inverter that I wanted to use for heating water.

Hey decp,

I intend on doing the same for the battery bank. Would you mind telling me which module kit you went for and any snags to watch out for?
What capacity?

Thanks.

decp · 22-05-2019 11:49am

Well the first big snag is that Jehu keeps changing the spec. He has posted some assembly videos recently that you should watch and maybe disregard the older ones or at least treat them as old revisions. I got a fireproof Schneider wall mount enclosure for £30 and free shipping on Amazon H400xW800xD120. The boards are from Jehu but you can download the schematic and DIY but no real advantage. The rest is from AliExpress, use Jehu's kit to select the correct parts. The design is fused at every level, from the full output to each board and each 18650 cell so its a good design. I added a lot of extra protection on the overpower and cut off for low voltage protection with a frost protection heater also as I dont keep this in the house. I collected the solar panels, inverter and solar charger from Ebay, Adverts and Donedeal and got great deals on all them. Its totally modular so you go as big or small as you want/need. Mine is 2.4Kwh at the moment but when I finish the two other stacks it will be 4.23Kwh based on the LG 18650 spec.

Home attached battery storage solution

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