What's your normal overnight SOC usage?

[HalfBaked]

Happy Saturday everyone!
Just trying to see what's normal/common. I typically see about a 10% average discharge of the battery bank overnight.
Curious what other's are seeing.

 

[TomC4306]

Depends how big the battery is.
50% of 15.8 Kwh.
Unless I leave the window AC on all night, then
65%. I need more battery.

 

[42OhmsPA]

Depends on the time of year...
Can you tell when the A/C stopped running as much overnight.

 

[wildbillpdx]

I'm only running part of my house on three LifePower4 batteries. Charge drops to about 35% overnight and recharges to 100% by mid to late afternoon.

 

[Quattrohead]

40%

 

[LydMekk]

Depends on terrain watering, AC, heating etc.
Down to 75-60%.
In the winter maybe lower.

 

[Shimmy]

Corollary question: how have people chosen to size their battery-- average overnight SOC, disaster mode, seasonal, three cloudy days, or "as much as I could fit/afford"?

 

[wildbillpdx]

or "as much as I could fit/afford"?

That's me! Need more PV panels and more battery. Maybe next year...?

 

[dougbert]

whole house is off grid (april to october) so what I produce, I store and consume daily


therefore, here is last night's discharge graph (voltage in blue) look at the PM time frame before Midnight

60 kwh battery capacity, night time discharge is 700 watts to 1000 watts

I produce 30 to 45 kwh per day (sunny)
20 to 25 kwh on cloudy days




here is todays from midnite

battery FULL is 49.4 volts
EMPTY is 40.0 volts

so i discharge about 1/3rd of battery between sun down and sun up - 15-20 kwh



and here is PV input and LOAD output, today

 

[timselectric]

10%

 

[OffGridInTheCity]

I've been growing my battery bank over the years to lower the average DOD. Currently I'm 14kw PV, 121kw battery, and 15,500kwh of consumption per year at an average DOD of 37.7% / cycle for 2023. It varies from a low of 26% (winter less PV) to a hi of 42% (spring-summer most PV) at the extremes.

Since I run 18650 NMC I believe a low DOD to be a key critical factor for a really long cycle life. I'm continuing to expand the battery bank slowly and hope to get even lower than 38%.

 

[Supervstech]

I've been growing my battery bank over the years to lower the average DOD. Currently I'm 14kw PV, 121kw battery, and 15,500kwh of consumption per year at an average DOD of 37.7% / cycle for 2023. It varies from a low of 26% (winter less PV) to a hi of 42% (spring-summer most PV) at the extremes.

Since I run 18650 NMC I believe a low DOD to be a key critical factor for a really long cycle life. I'm continuing to expand the battery bank slowly and hope to get even lower than 38%.

You have 121kWh of 18650's?
Wow...
I assume self built?
That took a LOT of time I bet.

 

[wattmatters]

I have my daily cycling capacity (15 kWh of LiFePO₄) and my outage reserve capacity (20 kWh of SLA). They operate as a hybrid battery bank.

So I go with these SOC ranges:
60% - 100% : Daily Cycling Capacity
Below 60% : Reserve Capacity, made up of:
30% - 60% : Grid Outage Reserve Capacity
0% - 30% : Emergency Reserve Capacity

Hence I tend to stay in the top 40% of total bank SOC. Here's the SOC (and bank voltage) since registering the data for the whole bank.



I increased daily cycling capacity from 10 kWh to 15 kWh in May this year, so the operational SOC ranges above were a little different, my daily cycling SOC floor was higher.

The daily cycling battery capacity is cycled pretty solidly.

I would not anticipate ever dipping into emergency reserve capacity SOC range, as a backup generator would be used by then for recharge. But it's there if we absolutely need it.

 

[Balrog006]

Started my build with ‘all I could budget for’ which was 30kwh, I cycle that down-between supplementing TOU and supplying overnight power, to about 60% currently. Once I see some of my 30% Fed payback the bank will increase to 45 or 60kwh which will add more reserve for poor charging days, outages and still allow running overnight while maintaining a reserve.