Solar PV battery options

celtic_oz

https://www.boards.ie/discussion/comment/117841433#Comment_117841433

I have this BYD battery (4Kw) .. what was the upgrade cost and did you do yourself ? TIA

unkel

Build your dreams or build your own dreams 🤣

MAULBROOK

https://www.boards.ie/discussion/comment/117842037#Comment_117842037

Fucx it let someone else build it, im just going to plug it in.

I'm all for a simple life. BYD

slave1

Re panels, my 18 2m x 1m panels were installed in 50minutes, 3 guys and their pace was off the charts. Ladder up, secure point put in place, rails in before my eyes, then one lad put in rails at rear of house while one guy with massive guns walked panels up ladder and third guy installed, they literally flew up

slave1

If I’m going DIY route, unheated attic is location of choice, I’d be laying them on 50mm rigid insulation board and then have a large insulation housing of same insulation ready for Winter months.

How would they get on in hot Summer times in attic?

graememk

As for the attic, in Ireland I wouldn't worry too much.

My attic hit 30 in July, but the batteries like it warm, preform thier best at that temperature.

(Mines in a room off the garage, putting some insulation around them kept them warm in the hard freezes.)

Charging them at night will keep them warm too.

reklamos

https://www.boards.ie/discussion/comment/117845513#Comment_117845513

Optimal battery temp is 25 C as this is what vendors usually test them at. Hence in the manuals you see the rating at 25 C. Some time ago I had found some research article that performed temperature testing on Lifepo4 batteries. The conclusions was that operating temperature range is 10-40 C. But from all the charts I could see that the best range is between 20-30 above or below start impacting charge/discharge rates, also there is capacity loss and then there is self discharge. For home users probably these figures are negligible but low/high temperatures may impact longevity of the battery.

I have my batteries in the insulated attic and during the heat wave the temperature was getting to 31 C in the attic where the batteries are located. The internal cell temperature was going up to 37. Having inverter in the same space also did not help with temps as with a lot of sun it was heating up the environment.

unkel

Fun fact. If you keep your lithium battery at a constant 21C and cycle it between 25% and 75% SOC, it will still have most of its capacity after 50 years!

slave1

So as I get a spare minute I look back on the opening pages of this thread, the batteries have gone from under €1,400 to €1,900 😐️

https://www.aliexpress.com/item/4001083766967.html?srcSns=sns_Copy&spreadType=socialShare&bizType=ProductDetail&social_params=20089728438&aff_fcid=95817855536e4b4190bae1804f4c8fc5-1631214668953-02519-_mtLHTeb&tt=MG&aff_fsk=_mtLHTeb&aff_platform=default&sk=_mtLHTeb&aff_trace_key=95817855536e4b4190bae1804f4c8fc5-1631214668953-02519-_mtLHTeb&shareId=20089728438&businessType=ProductDetail&platform=AE&terminal_id=932099ac2f1e4734b78f47e2a9839810

graememk

https://www.boards.ie/discussion/comment/117869756#Comment_117869756

Yeah they went up a while back.

They do (PWOD anyway) have EU stock now too.. and apparently they have a september "sale" on...

slave1

Need to put together a proper plan, need a second inverter and new strings to make batteries worthwhile....

unkel

Why would you need a second inverter / new panel strings?

DrPhilG

https://www.boards.ie/discussion/comment/117869938#Comment_117869938

Oye also advertising a September sale. No clue about stock location though.

slave1

https://www.boards.ie/discussion/comment/117870097#Comment_117870097

For half the year I wouldn’t be generating enough PV to charge the batteries, I want to avoid charging at night rate as much as possible. It’s a long term plan I have in mind. As a two EV household I’m around 20mW a year, current PV should do about 5.5-6mW, I’d like to get that closer to 10mW

unkel

Ah ok, so a major upgrade of your whole PV setup? With putting a limiter on so you can't export more than 6kW (but can produce a lot more than that)? Did you check if you get 3ph where you are and if so how much that costs? Could be as low as 2 grand. Lot of money but if you are to stay in your house for decades it might be worth it.

slave1

Na, won't be going 3ph, need to do the math and also the impact of no more WFH as I want to max my self consumption and minimise reliance on grid (apart from unavoidable EV night charging).

It's all in my head at the minute but I've a new role killing my hours and a bedroom to continue insulated slabbing and a new front driveway to finish off, not enough hours. When the dark Winter evenings come in I'll attack XL and work it all out, likely ~€4-5k so not to be jumped into

reklamos

You already have batteries in form of EVs. The only challenge is to have one in the driveway when it is sunny :)

unkel

The main challenge is to cleverly charge and discharge the EV(s). That's the holy grail (combined of course with having enormous renewable electricity generation as a country)

Charge up your massive batteries when electricity is cheap or nearly free. Then discharge the batteries and sell the electricity in them to the grid when the prices are at peak rates

@slave1 - there really is no reason not to cycle your battery. It should have thousands of cycles and only slowly degrade over time (over decades). Make full use of it! Load it up at night! But obviously don't charge your car from your battery.

bullit_dodger

+1 on that comment about cycling the batteries. That's why you bought them! :-)

garo

https://www.boards.ie/discussion/comment/117869756#Comment_117869756

These were 1600 two weeks ago because of some special sale. But that was the lowesat I have seen them for the past month and a half.

garo

https://www.aliexpress.com/item/4001083766967.html

Down to 1492. Less with coupons. I am very tempted to pull the trigger.

SD_DRACULA

Anyone here mixed and matched batteries, like two different brands on the same hybrid inverter? Is it even possible assuming the voltages match?

Mixing as in a pylontech or BYD or puredrive along with these lifepo4 cells.

Your man Will Prowse always has a bunch of them connected but not sure on his setup maybe no hybrid inverter and just uses charge controllers etc.

graememk

https://www.boards.ie/discussion/comment/117893606#Comment_117893606

The inverters that he uses are off grid, straight inverters, They shut off when they hit low voltage.

The inverters most of us have work best with some sort of BMS connection, mainly for SOC. I dare say it would be possible to mix and match, but not worth it.

garo

https://www.boards.ie/discussion/comment/117893409#Comment_117893409

So I see five different items on sale from oye:

https://www.aliexpress.com/item/4001083766967.html This is GradeA so presume it is return? Shipped from China, arrival in Dec and 1492

https://www.aliexpress.com/item/33041721907.html This has the Poland option grayed out and priced at 1930 for shipping from China and arrival in Dec.

https://www.aliexpress.com/item/1005002996273731.html Has a China option which is 1758 and arrival in Dec and a Poland option which promises delivery in Oct and costs 1932.

https://www.aliexpress.com/item/1005002996505994.html Another listing same as #3 above ut 20 EUR cheaper.

https://www.aliexpress.com/item/1005002352922010.html Shipped from China but slightly cheaper again.

These are all the same cells?

graememk

Yeah, I'd say they are all the same, CALB cells. There is some people complaining that they aren't new on the first one though.

Keep an eye on pwod too.

They all use the same pictures so could be the same warehouse

garo

Down to 1327 on the first link now. That is advertised as Grade A which usually means Used but "as new". The negative reviews are not particularly encouraging though.

There is another "new" listing for "Brand New" batteries for 1327 here: https://www.aliexpress.com/item/1005001552695839.html

They sure don't make it easy to figure out what is going on.

graememk

How much of a chance you want to take?

https://a.aliexpress.com/_mOTiMft

garo

Not that much of a chance :)

MAULBROOK

Dose anyone know if its ok to reduce the 10% battery minimum to 5% on a 10kw BYD battery.

Its a shame missing out on .5kw.

garo

I think that has a negative impact on battery life. It stresses a LiFePO4 battery and increases internal resistance.