Solar PV battery options

Don't even think about payback, go for it, it's more fun this way 😁

FIT will be useless and you can always fully charge the batteries on night rate in the bad months.

I'm looking at going from 5kwh to 20 myself, will probably never pay back (or payback in 2 years thanks to that stupid commie) but I don't care, I want to be able to do stuff like cook in the evenings without draining half the battery, gaming also wastes a ton of power in the evenings in the house, and still want to be going on battery until the next time the sun comes out, then winter time charge them at the EV night rate which might do me for the day, almost.

I might have missed an obvious thread for this, but is anyone operating batteries purely for load-shifting without panels connected? (cant seem to do a specific thread search these days)

Anyhow, I'd be technically competent to knock up a self-build battery system, neighbour is a spark and can certify mains connectivity if need be.

On my current Bord Gas day/night rural tarrif, there's 12c difference between day night which will increase next month. I'm just break-even on this rate now averaging 25% night usage on usage of 6500kWh/annum. By my reckoning I'd save €490pa after VAT and discounts if I could load-shift to 75/25 night day by battery cycling, about €250 pa for a 50/50 split.

Daily use averages 18kWh, but obvs more in the winter, say up to 24kWh/day.

So to move another 50% to nighttime battery charging year round, I'd need to allow minimum 10kWh battery pack?

Given cost to self-build this, am I likely to break-even anytime soon?

FYI, I have space for about 40sqm of panels on south facing garage, but it is partially shaded for 3 months of the year so would need optimisers to make best use of it. Haven't costed for panels recently, but would prefer to avoid the large capital outlay atm.

Likely to be acquiring an EV later this year, so would be charging nightime and this would improve the night/day ratio although increasing overall usage. Not sure the EV itself merits solar PV, if I can charge most anytime using nightrate from the batteries.

Thinking batteries will also help work around the worst of the punitive "smart meter" tarrifs when these are forced on us.

Thanks, that's pointed me in the right direction for some further reading. At that price I'd almost certainly go for 2x10kWh. Assume that BMS can take multiple inputs from mains/ PV inverter if I add some DIY panels.

Would ideally want to use as auto-backup when ESB is down (fairly regular in our area, at least 3 X 2 hour outages so far this year), but understand that may be trickier to implement. Have a manual c/o switch at present to switch from mains to generator input.

No BMS can distinguish between the voltages of paralleled cells...

If you want a 20kWh battery pack from 32 200Ah cells, you really should configure them as two parallel packs of 16S1P, each with their own BMS

Sale starts tomorrow until Friday

Is there any point? Even if you charge the whole battery every night at night rate, and use it all up at day rates, you will save 9kWh (usable) * (19c day - 9c night) * 80% round trip efficiency = €0.72 per day (€250 roughly per year), the system will cost you at least €2000 (if you buy really well) to setup plus the cost of the electrician

True enough. And what is missed quite a lot in these discussions as well is that night rate electricity in Ireland is much cleaner than day rate. It is already over 50% from wind. It's not all about money.

https://www.smartgriddashboard.com/#all

Also looking at 32 x 200Ah. What did you pay? I know these were €2500 incl shipping before Christmas but looks like never to be seen at those prices again

Ordered. Tks☺️

Best way to clean up your grid use is to max all your roofs with panels! I live in a small semi-detached house in a suburb of Lucan and I have 8kwp, producing about 7MWh per year. A typical house in Ireland (without EVs or heatpump heating) uses about 3MWh per year!

5 panels on kitchen extension, 5 panels on house roof (busy up there, already had 40 tubes and 3 velux windows) and indeed 14 panels on my large new shed, all south facing 😁

Someone was joking this morning, asked me how long it would take for the shed panels to actually pay for the build of the whole shed 😁

BTW my virgin road / north facing front of the house is next if / when panels would drop significantly in price. According to Quentin, a north facing typical roof angle panel in Ireland produces about 50% of a south facing panel, so could very well be worth it then. Would fit about 18 panels on that in theory minus a few panels for chimney shading...

Bought some more batteries from PWOD last night too, just got an email that they have already shipped

Photo could have been a lot worse 😂

I ordered 32 more CALBS, not quite sure what to do with them yet. I might sell my current 16 to someone who doesn't want to wait for 2 months for delivery from China. And install the 32 new ones. Payback period? Not too worried about that. But I am currently still load shifting. If you load shift 365 days a year with a 20kWh pack, that alone is worth about 18kWh (usable) * 365 * €0.1 (difference day and night rate) * 80% efficient round trip = over €500 per year. That alone makes for a decent payback! And the difference between day and night is likely further increasing.