On-grid domestic battery storage

1961Nick

EVandPV said:

Regarding temperature, what power settings is everyone using for ac charging ?
My Pylons sit at around 20°C or so when idle but get up to around 48°C when charging at full power (2.4kw). 
I don't see this as particularly warm so I'm not overly concerned, just wondering if there would be any point in reducing the power rate ? Would it significantly prolong battery life for instance ?

I grid charge @ 3kWh because that just fills them in the 4 hr Octopus Go window.

They spend all summer charging from solar at 3kWh so I can’t imagine there’ll ever be a temperature issue.

Solarchaser

Yeah same as Nick, charge them at 3k.
I think you are maybe looking at the lux temperature rather than the pylon temperature though mate, as I've never seen the batteries above 30c, even in summer.

EVandPV

Solarchaser said:

Yeah same as Nick, charge them at 3k.
I think you are maybe looking at the lux temperature rather than the pylon temperature though mate, as I've never seen the batteries above 30c, even in summer.

Ah cheers for that, think you could be right.
The Lux gives a huge list of data on the web portal and one column is labelled " t-inner °C" so assumed that was batt temp. After digging around a bit more I found one labelled "t-bat°C" but oddly the values are all zero.

Solarchaser

Weird, sounds like a call to think renewables is on the cards then.

EVandPV

Solarchaser said:

Weird, sounds like a call to think renewables is on the cards then.

I think it's possibly for lead acid batteries as the only thing temperature related in the settings is for lead acid.

mickyduck55

Pylontech Energy Storage System

3 X  3.5w (14KW) Pylontech US3000B Plus Lithium-Ion Battery Cells

1 x LUX AC controler

Installed today slightly cut down as decided to give the 4 th battery to my son who is having total system installed tomorrow .. 6kW PV and 3 US3000 batteries etc

Interesting to see how we get on!

Just over 13 K for both

Nice to be sitting here at night with the grid not supplying anything to run my home

1961Nick

Running your house through the night on free solar energy is very satisfying. The only time it's better is during a power cut.

Congrats on your system & I'm sure another US3000 will find it's way onto your stack before too long.

mickyduck55

1961Nick said:

Running your house through the night on free solar energy is very satisfying. The only time it's better is during a power cut.

Congrats on your system & I'm sure another US3000 will find it's way onto your stack before too long.

I did order 4 batteries for here but as stated decided to give one to my son so we had 3 each.. not sure 1 will need 4 but we will see.. my inverter will only run a couple of sockets in a power cut ?

EVandPV

mickyduck55 said:

1961Nick said:

Running your house through the night on free solar energy is very satisfying. The only time it's better is during a power cut.

Congrats on your system & I'm sure another US3000 will find it's way onto your stack before too long.

I did order 4 batteries for here but as stated decided to give one to my son so we had 3 each.. not sure 1 will need 4 but we will see.. my inverter will only run a couple of sockets in a power cut ?

With one Lux inverter, you'll get 3.6kw ouput but you can run 2 of them in parallel and get up to 7.2kw.

chamelion

I've visited and revisited battery storage probably every 6 months or so and each time get put off by the math. Doing a seriously quick back of the envelope calculation here's a scenario:
7.2kwh install for £3500 = 6.5kwh usable based on DoD. 

Optimistic outcome: 

• I charge it 100% through my PV array, so cost to charge = 0
• I use it exclusively during my agile octopus peak when it's let's say 22p/kwh. For sake of this optimistic math, I use up the full 6.5kwh in this period during electric peak.
• So my electric saving is £1.43/day
• break even point = 6.7 years

Balanced / more realistic outcome:

• Charge blended through PV and cheap overnight rates of 5p blended through the year (over winter won't generate enough to charge fully). Let's call it 50-50, that's 18p a day to charge after assumed round trip losses
• Cost savings based on my average per kwh price rate from agile. This week was 6.22p/kwh based on daily usage. Savings here for a full cycle then would be 40.4p. 
• So, savings here is 40.4p - 18p = 22.4p per day, or 81 quid a year. 
• break even point = 43 years, and this assumes no maintenance cost / inverter replacements etc.  

Is my math just completely wrong or am i not considering something important here? Sure, i'm assuming i'll always get cheap electricity, but at the same time i'm not considering drops in pricing of this technology, or it being eliminated entirely in favour of EVs charging houses during peak periods (imagine what a 75kwh tesla battery would do versus a 7.2kwh one in your closet!)