The Battery Thread (Solar / Inverter)

[Spizz]

I think it should be fine. The lithium battery should have a bms to protect it from overcharging.

When my batteries are full there's always a small amount of current going to the battery as the BMS needs this to operate. The inverter will interpret this as charging. I sometimes only have 20w going in to the battery and the inverter will show battery charging.

Can you see how much current is going to the battery? On my setup I can see if its 200w or 20w going into the battery.

I think it should be fine. The lithium battery should have a bms to protect it from overcharging.

When my batteries are full there's always a small amount of current going to the battery as the BMS needs this to operate. The inverter will interpret this as charging. I sometimes only have 20w going in to the battery and the inverter will show battery charging.

Can you see how much current is going to the battery? On my setup I can see if its 200w or 20w going into the battery.

Good to know about the battery. I’m trying to see in the manual how this all ties in together and need to find this out. I’ll have a look later when I get a minute and try to figure it out.

 

[TheChamp]

From the manual the default maximum charging current is set to 60A and the maximum utility charging current is set to 30A. I’m pretty sure these settings haven’t been changed but I’ll check later.

Excuse my ignorance, but I’m assuming you worked out the solar current of 10A from my solar set up, and knowing the other settings, what does this mean regarding the solar proving power to the house during the day? Does this more of less mean it’s not doing much due to the small number of panels? Would you recommend I change some settings somehow?

Yes, I worked out the current based on the general specs for these panels, it should be between 8 to just under 10A, all your panels are in series so they are as good as the current of one panel. 10A produces 2300W at 230Vac, which is way low and unlikely to even account for half of your power requirements. Your battery is working overtime during the day, as soon as it's charged it must get back to work so there is hardly time for it to maintain the charge.

The settings should be changed because I don't think the default are set to lithium. 60A looks fine for total current but if AC is set for 30A and solar can only produce 10A it looks like you have a shortfall of charging current, I am assuming the 4.8kWh will need between 50 to 60A but check on the battery specs and see what current is recommended, you will then need to up your AC charging current accordingly since AC is basically the primary charging source since there's not much to work with from solar, 30A from AC sounds slightly low.

 

[Spizz]

Yes, I worked out the current based on the general specs for these panels, it should be between 8 to just under 10A, all your panels are in series so they are as good as the current of one panel. 10A produces 2300W at 230Vac, which is way low and unlikely to even account for half of your power requirements. Your battery is working overtime during the day, as soon as it's charged it must get back to work so there is hardly time for it to maintain the charge.

The settings should be changed because I don't think the default are set to lithium. 60A looks fine for total current but if AC is set for 30A and solar can only produce 10A it looks like you have a shortfall of charging current, I am assuming the 4.8kWh will need between 50 to 60A but check on the battery specs and see what current is recommended, you will then need to up your AC charging current accordingly since AC is basically the primary charging source since there's not much to work with from solar, 30A from AC sounds slightly low.

Okay, I think I'm slowly understanding what's going on. My son gave me an explanation on the fundamentals in the car while driving him to school

First of all though, the battery is not discharging during the day or night. It is set to sit at full charge until there is loadshedding. I'm happy with this just now as that was the point of the install, to keep the house on line. Although now I've started I'm pretty keen to continue and go off grid completely, but that's for later.

So as it stands now, after loadshedding and the battery has run down to whatever level, I'm assuming the battery will then take longer to charge back up due to the shortfall of charging current which adds up to 30+10 from AC and solar?

Now the battery spec says "Charging limited voltage 54.0 V" and "Max. charging current 100.0 V", so I'm assuming we want to get it in the 54 to 100 range, so if for example we stick with 60A because the settings are in increments of 10 so choice is 50,60,70 etc, then it would be a good idea to set the AC to 50A to compliment the 10A from the solar, this would make 60A and this will charge the battery back at a decent rate?

Am I understanding this correctly?

 

[wingnut771]

Now the battery spec says "Charging limited voltage 54.0 V" and "Max. charging current 100.0 V", so I'm assuming we want to get it in the 54 to 100 range, so if for example we stick with 60A because the settings are in increments of 10 so choice is 50,60,70 etc, then it would be a good idea to set the AC to 50A to compliment the 10A from the solar, this would make 60A and this will charge the battery back at a decent rate?

Am I understanding this correctly?

Think you meant to say "A" amps here.

Anyway, I don't think the amount of current you use to charge is really important, just as long as its less than 100A. It will just take longer, twice as long @ 50A. For example: if it takes 1 hour to charge @ 100A, it will take 2 hours @ 50A and so on. I would stick to 50A as it's less stress on the batteries. So, solar being 10A, it will take 10 hours to charge which obviously isn't possible, there isn't enough sun hours in the day in theory. Now you need to work out how much kwh needs to go back into the battery after loadshedding to work out your charge time. For example, you have a 4.8kwh, you use 2kwh during loadshedding. Your 10A @ 220V solar = 2200W, would only take an hour to charge your battery back up so it's fine assuming you have no other loads running at the time. If your loads are 1000W then solar in perfect conditions will take 2 hours to do the same as you only have 1200W to play with.

You could parallel another string but even that wouldn't work because of your roof makeup. One string facing north is giving you 10A, but the east facing will only give 10A in the morning (while north facing is still picking up and is probably only sitting on 5A) and the west facing only in the afternoon (while north facing is dropping off), so at max you'll probably only get 15A average.

I see this inverter only has 1 MPPT. Can you parallel strings facing different directions on the same controller?

Can someone check my work?

 

[TheChamp]

Okay, I think I'm slowly understanding what's going on. My son gave me an explanation on the fundamentals in the car while driving him to school

First of all though, the battery is not discharging during the day or night. It is set to sit at full charge until there is loadshedding. I'm happy with this just now as that was the point of the install, to keep the house on line. Although now I've started I'm pretty keen to continue and go off grid completely, but that's for later.

So as it stands now, after loadshedding and the battery has run down to whatever level, I'm assuming the battery will then take longer to charge back up due to the shortfall of charging current which adds up to 30+10 from AC and solar?

Now the battery spec says "Charging limited voltage 54.0 V" and "Max. charging current 100.0 V", so I'm assuming we want to get it in the 54 to 100 range, so if for example we stick with 60A because the settings are in increments of 10 so choice is 50,60,70 etc, then it would be a good idea to set the AC to 50A to compliment the 10A from the solar, this would make 60A and this will charge the battery back at a decent rate?

Am I understanding this correctly?

Yes, you are understanding correctly.

I still have some questions on the battery utilization, how was the installation done, is the DB split for loads on the inverter or is everything connected to the inverter and it manages the load on it's own?

What is the input priority set to on.the inverter solar or utility? Can solar be used together with mains?

 

[Spizz]

Think you meant to say "A" amps here.

Anyway, I don't think the amount of current you use to charge is really important, just as long as its less than 100A. It will just take longer, twice as long @ 50A. For example: if it takes 1 hour to charge @ 100A, it will take 2 hours @ 50A and so on. I would stick to 50A as it's less stress on the batteries. So, solar being 10A, it will take 10 hours to charge which obviously isn't possible, there isn't enough sun hours in the day in theory. Now you need to work out how much kwh needs to go back into the battery after loadshedding to work out your charge time. For example, you have a 4.8kwh, you use 2kwh during loadshedding. Your 10A @ 220V solar = 2200W, would only take an hour to charge your battery back up so it's fine assuming you have no other loads running at the time. If your loads are 1000W then solar in perfect conditions will take 2 hours to do the same as you only have 1200W to play with.

You could parallel another string but even that wouldn't work because of your roof makeup. One string facing north is giving you 10A, but the east facing will only give 10A in the morning (while north facing is still picking up and is probably only sitting on 5A) and the west facing only in the afternoon (while north facing is dropping off), so at max you'll probably only get 15A average.

I see this inverter only has 1 MPPT. Can you parallel strings facing different directions on the same controller?

Can someone check my work?

I'm not so sure about the inverters capabilities. That's way baove my understanding at the moment so I'll need to investigate that one.

But yep, I'm going to have to really think about how to progress with additional panels. Due to the east/west roof set up it seems like I'll have to fork out at least 25% more cash to achieve the amps I will need.

Thanks for the easy to follow explanations, I'm now piecing this together very nicely how it all works.

 

[Spizz]

Yes, you are understanding correctly.

I still have some questions on the battery utilization, how was the installation done, is the DB split for loads on the inverter or is everything connected to the inverter and it manages the load on it's own?

What is the input priority set to on.the inverter solar or utility? Can solar be used together with mains?

They had to redo my DB and install a new one due to the mixed circuits. It was a bit of a mess apparently. Now in my understanding the whole house apart from the geyser is running through the inverter.

So from the manual I've got it set to Solar first. Here's the options, I'm on SOL.



(program 12 is set to 46V)

So yes, as per the post from last night you can see the priorities day and night in the pics.

Battery is set to stay fully charged and only used in event of loadshedding.

Day has solar supplying the house, charging the battery if necessary, and house backed up by utility. So solar and mains together.

Night is only utility bypassing the battery yet keeping the battery charge full. So mains only.

I need some advice or comments please. I'm a real noob as explained over th last page or two, but to remind y'all my set up is 6 x 320 PV panels, a Synapse 5.0+ inverter hooked up to a 4.8KWh battery. It was initially intended as a load shedding solution but I took advice and I added the PV to help with reducing the Eskom draw during the day.

So I have set up the priorities so that in the daytime the house will run on the solar backed up by Eskom for additional needed loading. If Eskom goes off loadshedding, then the battery will back up the solar.

At night the house is run on Eskom with the battery standing by topped up in reserve in case of loadshedding so the battery will kick in and run the house during that period.

So as it is essential that the battery is topped up to 100% to meet both load shedding scenarios, I have set it to charge the battery back to "full" should it be used in reserve as described.

So, the issue is that the battery is now constantly shown as charging in the display and the charging light is on full time and I'm wondering if this will damage the battery. I know cellphones have management systems for trickle charging and automatic cut off etc, but will this type of battery? It is LiFePO4 so it is apparently safer, but I'm wondering if this is just normal for these type of inverters to show as 'charging' as I've read they don't read battery levels very well.

Here's the photos from day and night to show the scenarios.

View attachment 1030408

View attachment 1030410

I hope that's clear now

 

[wingnut771]

I'm not so sure about the inverters capabilities. That's way baove my understanding at the moment so I'll need to investigate that one.

But yep, I'm going to have to really think about how to progress with additional panels. Due to the east/west roof set up it seems like I'll have to fork out at least 25% more cash to achieve the amps I will need.

Thanks for the easy to follow explanations, I'm now piecing this together very nicely how it all works.

The problem with amps is you need thicker cable to handle it. Better to try up the voltage by making the string longer. That way you don't need to run heavier cable and with the higher voltages there is less of a voltage drop over distance. Maybe use a combiner box to parallel the strings so you only run a short thick cable to the inverter?

Can someone check my work?

 

[Charlesjjm]

Battery is set to stay fully charged and only used in event of loadshedding.

From your settings this does not seem to be the case. It will use battery power during the day if there is not enough solar available.

 

[Spizz]

From your settings this does not seem to be the case. It will use battery power during the day if there is not enough solar available.

You know I was reading that back after I posted and thought wait a minute, you are right. I'm trying to think what other settings I changed now because as you can see from the photos it is solar and utility running the show with battery on standby. Too busy at work so will grab the manual at lunchtime and run through it again.

 

[wingnut771]

You know I was reading that back after I posted and thought wait a minute, you are right. I'm trying to think what other settings I changed now because as you can see from the photos it is solar and utility running the show with battery on standby. Too busy at work so will grab the manual at lunchtime and run through it again.

Think you need the SUB option? Although, the setting you are on will help reduce your power bill.

 

[Spizz]

Think you need the SUB option? Although, the setting you are on will help reduce your power bill.

Yeah, I’m a bit confused again.

But unfortunately I don’t have the SUB option and funny thing is, the way I read this SOL yesterday was that that was what was happening. And weirder still, it looks like that is what is happening according to the inverter pics.

So I’m wondering if I’ve fluked it by my setting the battery to be topped up to full before it is utilised again? So that the constant ‘charging’ discussed earlier is actually stopping the battery from joining back in to the back up to solar and instead the utility is taking its place?

 

[wingnut771]

Yeah, I’m a bit confused again.

But unfortunately I don’t have the SUB option and funny thing is, the way I read this SOL yesterday was that that was what was happening. And weirder still, it looks like that is what is happening according to the inverter pics.

So I’m wondering if I’ve fluked it by my setting the battery to be topped up to full before it is utilised again? So that the constant ‘charging’ discussed earlier is actually stopping the battery from joining back in to the back up to solar and instead the utility is taking its place?

Maybe what you need to do is set your battery low cutoff at fully charged voltage then maybe it will then use the grid when solar isn't enough, then during loadshedding, change it back.

I don't know, can someone check my work?

I just really wished you spent the extra 5k and when with a sunsynk.

 

[TheChamp]

From your settings this does not seem to be the case. It will use battery power during the day if there is not enough solar available.

That's what I was getting to. Solar will never be enough in this instance so the battery will always be called upon to provide some power.

 

[TheChamp]

Maybe what you need to do is set your battery low cutoff at fully charged voltage then maybe it will then use the grid when solar isn't enough, then during loadshedding, change it back.

I don't know, can someone check my work?

I just really wished you spent the extra 5k and when with a sunsynk.

Yes, that can work if it doesn't conflict with some other setting.

 

[Spizz]

Maybe what you need to do is set your battery low cutoff at fully charged voltage then maybe it will then use the grid when solar isn't enough, then during loadshedding, change it back.

I don't know, can someone check my work?

I just really wished you spent the extra 5k and when with a sunsynk.

As I said, it was a simple loadshedding beater that grew arms and legs. But this is helping big time and I’ll keep investigating and plan to add on at some stage. Maybe then use the Sunsynk you speak of as the primary inverter and employ the Stnapse I have in some other way.

But regarding your suggestion, is this what you mean by setting the battery low cutoff to fully charged? That’s the setting I have at the moment and maybe why I reckon I’ve fluked it.

Pen is pointing to it.

 

[wingnut771]

As I said, it was a simple loadshedding beater that grew arms and legs. But this is helping big time and I’ll keep investigating and plan to add on at some stage. Maybe then use the Sunsynk you speak of as the primary inverter and employ the Stnapse I have in some other way.

But regarding your suggestion, is this what you mean by setting the battery low cutoff to fully charged? That’s the setting I have at the moment and maybe why I reckon I’ve fluked it.

Pen is pointing to it.

Maybe. I remember you saying you set something to 46V. I'm not familiar with axpert like inverters, maybe someone else can comment?

 

[Spizz]

Maybe. I remember you saying you set something to 46V. I'm not familiar with axpert like inverters, maybe someone else can comment?

Here’s a setting that is saw yesterday and the reason I set the thing to Solar first.

Edit: 46V was the setting under "Setting voltage point back to utility source when selecting SBU or SOL"

 

[Spizz]

And I just cycled through the display settings and wrote down the figures shown. I’m don’t know what anyone can tell from that regarding further configuration?

 

[TheChamp]

As I said, it was a simple loadshedding beater that grew arms and legs. But this is helping big time and I’ll keep investigating and plan to add on at some stage. Maybe then use the Sunsynk you speak of as the primary inverter and employ the Stnapse I have in some other way.

But regarding your suggestion, is this what you mean by setting the battery low cutoff to fully charged? That’s the setting I have at the moment and maybe why I reckon I’ve fluked it.

Pen is pointing to it.

I think it's program 29 that we are looking for, the low battery cutoff.