Home attached battery storage solution

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.

unkel · 22-05-2019 12:32pm

Nice work, decp, would love to see a detailed post about the setup!

I presume your battery is 24V? How many 18650 did you use and what setup, something like 7s40p with 280 batteries? Where did you get the batteries? I could probably get my hands on a hundred or so cells, but they would be of varying quality / SOH / capacity, so not really ideal. I would make a 48V system if I went for it. What BMS did you use?

What inverter do you use with it? What's the max amp discharge you have used? Do you use it as an offgrid system to power your shed or what's its use?

decp · 22-05-2019 12:59pm

So the BMS is a Jehu board that is made for his setup. Its a 7s48p, I use 12 per stack and 4 stacks. I am currently working on it as I built two stacks to get it up and running and now I am adding the two other stacks, so I can post photos but here is one stack with 12 boards and the BMS board in the center with an XT90 connector. I went with new LG18650 3200mah for around €2.08 per cell from Aliexpress. The inverter is a Victron Phoenix 3kw (6kw peak), lovely bit of kit even if it is old and well used. This is my solar shed project before I tackle the house but I am very interested in a trickle power to an immersion heater idea. I could bypass the DC end of things and go AC from the panel. Much less loss and cost.
https://imgur.com/i3wRuZo

unkel · 22-05-2019 10:09pm

They are cheap batteries. Any link? Does that include shipping? Did you get stung for VAT / import duties / admin charges?

Would you do a breakdown of the total cost of materials (shipped to your door) for the build of the battery?

unkel · 22-05-2019 10:14pm

decp wrote: »

I am very interested in a trickle power to an immersion heater idea. I could bypass the DC end of things and go AC from the panel. Much less loss and cost.

I presume you mean the other way around: use the DC from your panels (bypass the AC end) to directly drive a DC element heating your water?

decp · 23-05-2019 7:52am

unkel wrote: »

I presume you mean the other way around: use the DC from your panels (bypass the AC end) to directly drive a DC element heating your water?

So I have a micro grid tie inverter that connects to a solar panel and converts the DC output to AC. I can post links next week (away now).

decp · 23-05-2019 7:56am

unkel wrote: »

They are cheap batteries. Any link? Does that include shipping? Did you get stung for VAT / import duties / admin charges?

Would you do a breakdown of the total cost of materials (shipped to your door) for the build of the battery?

Bought the batteries on AliExpress from Chinese company but the shipped from the Netherlands?? So no vat or duty. Will post links later..

unkel · 23-05-2019 4:35pm

decp wrote: »

So I have a micro grid tie inverter that connects to a solar panel and converts the DC output to AC. I can post links next week (away now).

Far more efficient to connect the panel directly to the element. Bit tricky to match up the two though. You will need to do a bit of research into Ohm's law

decp · 08-06-2019 12:26pm

Here is the link to the batteries. I bought in a sale but they are cheap and tested above the 3000ma rating.
https://www.aliexpress.com/item/100-New-Original-HG2-18650-3000mAh-battery-18650HG2-3-6V-discharge-20A-dedicated-For-LG-Electronic/32868746648.html?spm=a2g0s.9042311.0.0.27424c4dj8lXIf

rolion · 10-06-2019 10:20am

Your target project HERE .

air · 10-06-2019 10:49am

Honestly I think the DIY 18650 route is not the way to go for household level projects. Way too much work just piecing together the battery before you even get to the BMS and integration.
Used EV modules are a far better proposition if you can source them.
I've been using several for years now.

I have plenty of 18650s myself that I get free from old laptop packs but I reserve them for torches, power banks and other small scale projects to which they are much better suited.

Home attached battery storage solution

Comments