PV back on the table?

[Ken]

I now feel that with increasing leccy costs in April 2022 and reduced cost of PV that PV is now firmly back on the table. Perhaps with ROR better than its ever been? 6kw system for £4.5k and leccy at 25p/kwh becomes a no brainer in my book.

I also believe batts may have now become viable with much reduced costs from China but not sure how to get the sophisticated control required without buying a all in system.

[Stinsy]

All-in-one MPPT/inverter/charger is by far the simplest, cheapest, and most space-efficient solution. But you can also get AC coupled battery systems separate from the solar inverter.

[Ken]

Thanks Stinsy but i am also wondering how to control grid and pv charging times/amount and supply times to max use TOU tariffs. Nowty has explained this very well here and elsewhere but he does start from having plyontech batts which seem to be contollable. If i bought batts from China they would not come with this programability so then what.

[Stinsy]

Thanks Stinsy but i am also wondering how to control grid and pv charging times/amount and supply times to max use TOU tariffs. Nowty has explained this very well here and elsewhere but he does start from having plyontech batts which seem to be contollable. If i bought batts from China they would not come with this programability so then what.

Pylontech batteries are Chinese and are about as cheap as batteries get!

You can buy “B grade” lifepo4 batteries from alibaba that are very slightly cheaper than Pylontech but you’d need to connect your own BMS, eg this one: https://www.amazon.co.uk/LiFePO4-Batter ... 09LS1NKVW/ and make up all the connecting cables, etc.

You could then tell the inverter/charger that they are lead/acid batteries and set the voltages manually. The inverter/charger will then have charge/discharge settings. So you can set it to charge during the cheap period, and target zero import/export via a CT for the rest of the time.

I’d be up for making my own battery pack if it was cost-effective to do so. But frankly it isn’t.

[Joeboy]

Thanks Stinsy but i am also wondering how to control grid and pv charging times/amount and supply times to max use TOU tariffs. Nowty has explained this very well here and elsewhere but he does start from having plyontech batts which seem to be contollable. If i bought batts from China they would not come with this programability so then what.

You need a hybrid inverter. My massive experience extends to one only. Goodwe 3600sbp. Not a push but somewhere to start so you can get you head around where you're heading. Cheers!

https://www.goodwe.com/energy-storage-i ... es-285.asp

P.S If i could do it again or when this one craters i'd buy the 5000.

[Ken]

Thanks chaps.

What sparked this off was speaking to a guy who recently imported 30kwh for £3000 app delivered from china/alibaba. No expert but that sounds very good to me. I am going to contact him further to find exact Co.

Ken

[Stinsy]

£100 a kWh is too good to be true I’m afraid. I think the guy you were talking to was “mistaken”.

I’ve just priced up 15x 200Ah 3.2V lifepo4 batteries on alibaba. Comes to £1531.88 inc shipping. That is 9.6kWh of batteries or about £160 a kWh (+customs handling, import duties, etc.). Then you need a BMS, cabling, connectors, etc., and you’ll have to wait about 4 months for them to come.

As I said: you can build your own battery pack for less than the cost of a Pylontech but not by enough to make doing so worthwhile.

Here is an example: https://www.ebay.co.uk/itm/353794077997/. Everything you need to make a c. 3.5kWh 12V battery pack. In the UK, import duties etc. paid, ready for quick delivery. Works out at c. £250 a kWh, compared with c. £300 a kWh for Pylontech it is a good price. But then the Pylontech batteries come neatly packaged with a warrantee…

[nowty]

Well maybe £100 cannot be achieved anymore but my second hand growatt lithium battery banks (some were actually as new as never installed) cost me an average of £100 per kWh several years ago and are still as good as ever. Another guy on here managed to buy a number of faulty growatt packs (most cells ok) for about £30 per kWh as the seller had no idea of their value.

I will have to re-write the thread having lost it twice with the website shenanigans.

Part of my battery banks



Lithium cell balancers

[Stinsy]

You timed it perfectly. A load of people had been sold the growatt batteries, who knew nothing about them. IIRC, they had failure-prone control circuitry so frequently came up for sale as “not working”, however the actual batteries were sound.

Used batteries, come up very infrequently nowadays, the seller usually knows what they have, and they usually sell for close to full-retail even in damaged or unknown condition.

I’d be very keen to revisit your battery system (again). It really is a thing of beauty!

[nowty]

You timed it perfectly. A load of people had been sold the growatt batteries, who knew nothing about them. IIRC, they had failure-prone control circuitry so frequently came up for sale as “not working”, however the actual batteries were sound.

Used batteries, come up very infrequently nowadays, the seller usually knows what they have, and they usually sell for close to full-retail even in damaged or unknown condition.

I’d be very keen to revisit your battery system (again). It really is a thing of beauty!

There was a golden opportunity of about a 1 year window when you could readily pick them up cheap, before people got wind of how valuable they were and now almost none come up anymore and to be honest if they did come up now they would be circa 5 years old so they could have had a hard life.

I'll do a full cell voltage check soon and use that as an excuse to re-document some if it.