We had 8 panels and 5kva battery installed 6 months back in winter and I read that it should not be allowed to run below 40 SoC. We have dual Eskom and Solar and therefore I noted the battery was charging 3 to 4 times a night from Eskom and its staying power was diminishing.

I contacted installer who monitored and said there appeared to be a battery fault and he changed it out at for free. I have noted with the new battery in plav=ce that the battery is capable of running my house from  at 18h00 to past 2 am when the 40% SoC triggers a charge from Eskom. My question is can I let it run down to 20% SoC which means that it can support the house at that rete till past 5 am when being summer, solar feed is already coming in again.

What does this do to Battery Health if we allow such discharge 110% to 20% every evening? This will however also reduce the quick charges initiated by ESkom trigger,

Thanks

 

Greg

sorry typo last sentence should be 100% to 20% m=not 110.

36 minutes ago, GregM1 said:

We had 8 panels and 5kva battery installed 6 months back in winter and I read that it should not be allowed to run below 40 SoC. We have dual Eskom and Solar and therefore I noted the battery was charging 3 to 4 times a night from Eskom and its staying power was diminishing.

I contacted installer who monitored and said there appeared to be a battery fault and he changed it out at for free. I have noted with the new battery in plav=ce that the battery is capable of running my house from  at 18h00 to past 2 am when the 40% SoC triggers a charge from Eskom. My question is can I let it run down to 20% SoC which means that it can support the house at that rete till past 5 am when being summer, solar feed is already coming in again.

What does this do to Battery Health if we allow such discharge 110% to 20% every evening? This will however also reduce the quick charges initiated by ESkom trigger,

Thanks

 

Greg

What type/model/size of battery is that?
LifePo4 can under normal use usually be discharged safely down to 20%.

The 40% level set by your installer is most likely to preserve and extend the battery life for whatever reason they suggest.

13 minutes ago, WannabeSolarSparky said:

What type/model/size of battery is that?
LifePo4 can under normal use usually be discharged safely down to 20%.

The 40% level set by your installer is most likely to preserve and extend the battery life for whatever reason they suggest.

The 40% I guess is also used to have at least this amount of power the last time the grid was on I order to be ready for LS. 

@GregM1 Yes it can be reduced to 25% to use less grid power and recharge in the morning. Just note some batteries cut out at 20% via the BMS. Keep above the cut out point. 

Thanks for the feedback

 

The battery is a 

Vestwoods Lithium-ion Battery LifePO4 Battery VT48100 - 100AMP / 5.1KWh.

 

I do agree that 205 might be low if we hit a 3hour plus load shedding period from midnight onwards and we run the risk of the invertor shutting down.

 

From the answers above I am gathering the idea that maybe I should leave it at 40% and let Eskom kick in early hours of the morning.

 

My reluctance on this is that on any good day, even in winter the sun has it at 100% by between 11 and midday and the afternoon sun is just wasted on solar. So my mind says why did I let Eskom do a early morning top-up.

 

Thanks

 

Greg

 

 

20% shouldn't be a problem, and most brands can be run down to 10 and will then shut down automatically.

The reason 40% is recommended is that if there's load shedding, and no PV (NB! this could be an overcast morning) you know you will have 40% to run with. OK... actually 30%. But since I use about 20% overnight, 30% is going to give me a decent cushion. 

Usually the inverter has TWO limits. So mine is set to not discharge past 40% remaining when grid is present, and to go all the way to 10% remaining when the grid is down. 

We all go through this early phase of figuring out just what we have. One thing is to get as much as possible done during the day when the sun is up. So, for EG, I have timers on the water heating, we don't run things like the dishwasher at night. Because we got good at this, we draw 200 to 300 W through the night, so, with 10kWh of battery, we get through the night with something still in the bank. Most days the battery is recharged by 11:00, so then we have lots of PV to do stuff with. 

So watch your system. Watch which loads kick in when (you will find you soon start identifying them). See what you can do without at night. This way you can stretch the battery a bit further and it won't need to bother Eskom as often.

4 hours ago, GregM1 said:

Thanks for the feedback

 

The battery is a 

Vestwoods Lithium-ion Battery LifePO4 Battery VT48100 - 100AMP / 5.1KWh.

 

I do agree that 205 might be low if we hit a 3hour plus load shedding period from midnight onwards and we run the risk of the invertor shutting down.

 

From the answers above I am gathering the idea that maybe I should leave it at 40% and let Eskom kick in early hours of the morning.

 

My reluctance on this is that on any good day, even in winter the sun has it at 100% by between 11 and midday and the afternoon sun is just wasted on solar. So my mind says why did I let Eskom do a early morning top-up.

 

Thanks

 

Greg

 

 

Yes that is the bit that one must work out for your own loads and how long you can/want to rely on the battery.