Jump to content

How reliable are hybrid systems really?


Bobster.

Recommended Posts

OK... I'm not going to name my installer here because I don't even know how concerned I should be yet.

My system (see signature) was installed in June. Early on there were problems with the inverter not being able to accurately track the SOC of the battery. This was addressed with a firmware upgrade that improved matters markedly.  But still... every now and then the inverter just loses sight, so to speak, of the battery. It doesn't report 0% SOC, it just reports that there is no battery.

If I restart the system, the battery will become available again, once the solar panels start delivering power. The installer tells me that if I just do nothing and wait for the sun to come up then the battery will automagically become available again.

This happened this week. Battery vanished at 18:45. Came back on (with SOC shown at 87%) around 5:30 the next morning.

This is the 3rd such incident since July. Installer is usually very helpful, comes out, checks the system and the system then runs well for weeks and then the battery just vanishes again. If it vanishes during the day then this is no big deal providing somebody can get home before sun down. It if happens in the evening, as it did this week, then we have no protection against load shedding - one of the reasons I bought the system.

AFAIK there is no connection between the BMS and the inverter. I'm no engineer, so I don't understand how the inverter monitors SOC in this case.

Usually it's charged by 10:30 on a sunny day. Thereafter it goes into a sort of trickle charge mode, usually drawing about 120 w, which I assume is just staying topped up. Another issue that has cropped up recently is that it goes into trickle charging before the SOC is shown at 100%. OK... maybe the displayed SOC is wrong - though it always gets to 100% eventually (gets to about 85% very fast, then takes a long time for last 15%).

So is this just how it is? These systems are a little delicate, not perfectly reliable and one just has to learn to live with that? I don't know if I'm being impatient and unreasonable or not.

Link to comment
Share on other sites

51 minutes ago, Bobster said:

So is this just how it is? These systems are a little delicate, not perfectly reliable and one just has to learn to live with that?

no. What you describe is not normal at all. There is something wrong with your system and you have the right to have it fixed. I would keep on pushing the installer,  Goodwe and Revov for solutions. In my experience (comparing it with a BMV 702) the Goodwe has very good SOC tracking. The next time the inverter does not see the battery I would check (with a multimeter) if maybe the battery has switched off for some reason. I would also double check all the set inverter battery parameters. It is very important that the charge voltages, Ah capacity, tail current and tail current time before going to float are correct.

Link to comment
Share on other sites

3 hours ago, Fuenkli said:

no. What you describe is not normal at all. There is something wrong with your system and you have the right to have it fixed. I would keep on pushing the installer,  Goodwe and Revov for solutions. In my experience (comparing it with a BMV 702) the Goodwe has very good SOC tracking. The next time the inverter does not see the battery I would check (with a multimeter) if maybe the battery has switched off for some reason. I would also double check all the set inverter battery parameters. It is very important that the charge voltages, Ah capacity, tail current and tail current time before going to float are correct.

Well what I can tell you is that there is some sort of control unit atop the revovs and whenever the battery gets "lost" all the lights in that box are off. Which maybe points us to the root of the problem. There is a reset button, but when I push that the LEDs strobe, the unit beeps and the error light comes on.

The Goodwe is always able to restart the battery pack when it gets solar power.

Thanks for the reply.

How do I check if the battery is off? Just measure across the terminals? Or at the DC circuit breaker?

Link to comment
Share on other sites

18 minutes ago, Bobster said:

How do I check if the battery is off?

you can measure the voltage anywhere between the battery and the inverter. 

 

22 minutes ago, Bobster said:

The Goodwe is always able to restart the battery pack

That is interesting. I wonder how your battery works because as you have mentioned there is no communication cable between the battery and the inverter. Maybe you can contact Revov to get some information about this?

Link to comment
Share on other sites

3 minutes ago, Fuenkli said:

you can measure the voltage anywhere between the battery and the inverter. 

 

That is interesting. I wonder how your battery works because as you have mentioned there is no communication cable between the battery and the inverter. Maybe you can contact Revov to get some information about this?

I know that it's a feature that Goodwe offer but which is turned off by default. I know that it involves sending a burst of power to the battery (the app warns you).

I just went to physically recheck. The only connections between the inverter and the battery are those carrying the current via the circuit breaker.

Link to comment
Share on other sites

4 hours ago, Fuenkli said:

I would also double check all the set inverter battery parameters. It is very important that the charge voltages, Ah capacity, tail current and tail current time before going to float are correct.

I'm bang to fiddle with that stuff. Keen (because by instinct I'm a tinkerer), but also bang. I don't know what most of them mean anyway and what the effect of changing them would be. The installer did come around a month or so again to change them on the basis of new information received from Revov. As I said, the system can work reliably for weeks. The problem is an intermittent one.

Link to comment
Share on other sites

6 minutes ago, Bobster said:

The installer did come around a month or so again to change them on the basis of new information received from Revov

can you give us the settings the installer has programmed? Maybe we can spot the problem. What parameters does Revov recommend?

Link to comment
Share on other sites

22 hours ago, Fuenkli said:

can you give us the settings the installer has programmed? Maybe we can spot the problem. What parameters does Revov recommend?

Thanks for your input so far. @Fuenkli

I've attached screen shots of the settings as per ezManage

The system is still playing up. Last night at about 20:00 and with SOC showing 92% the inverter started drawing from the grid. This carried on until about 5 this morning when the battery "vanished again". It restarted about 5:45 with SO now showing at 87% (despite no draw from the battery overnight). 

So again, if there was load shedding last night I'd have had no protection. 

I cant answer your 2nd question now. I will neef to drop Revov a line. Problem is the invoice doesn't even tell me what model Revov pack i have. 

 

Screenshot_20191123_185304_com.goodwe.EzManage.jpg

Screenshot_20191123_185244_com.goodwe.EzManage.jpg

Link to comment
Share on other sites

23 hours ago, Fuenkli said:

can you give us the settings the installer has programmed? Maybe we can spot the problem. What parameters does Revov recommend?

Thanks for your input so far. @Fuenkli

I've attached screen shots of the settings as per ezManage

The system is still playing up. Last night at about 20:00 and with SOC showing 92% the inverter started drawing from the grid. This carried on until about 5 this morning when the battery "vanished again". It restarted about 5:45 with SO now showing at 87% (despite no draw from the battery overnight). 

So again, if there was load shedding last night I'd have had no protection. 

I cant answer your 2nd question now. I will neef to drop Revov a line. Problem is the invoice doesn't even tell me what model Revov pack i have. 

 

Link to comment
Share on other sites

54 minutes ago, Bobster said:

I've attached screen shots of the settings as per ezManage

the charge voltages are a bit high. According to the Revov spec I found on the web bulk and float should be 54.4

https://www.sustainable.co.za/revov-2nd-life-200ah-10-2kwh-lifepo4-battery.html

Also check the battery capacity in EzManage or PV Master. It should be 200Ah. 

I would also lower the discharge depth to 90% and increase the charge current to 100A. Their warranty covers this.

52 minutes ago, Bobster said:

Traces from SEMS showing the battery being ignored and then getting lost and found.

 i can see the problems. If you can measure the voltage from the battery into the inverter during the time the inverter does not detect the battery. Also check the battery LED on the inverter. It should be on if a battery is connected. I would also look at the real time values with EzManage. Do they align with SEMS. Another test you can do during the time the inverter ignores the battery at night is to simulate a grid failure and check if you have power on the back up output.  

Just had another idea. Shut down and restart the inverter and see if it fixes the problems. All your findings will help Goodwe and Revov to hopefully find and fix the problems

Edited by Fuenkli
Link to comment
Share on other sites

15 minutes ago, Fuenkli said:

the charge voltages are a bit high. According to the Revov spec I found on the web bulk and float should be 54.4

https://www.sustainable.co.za/revov-2nd-life-200ah-10-2kwh-lifepo4-battery.html

Also check the battery capacity in EzManage or PV Master. It should be 200Ah. 

I would also lower the discharge depth to 90% and increase the charge current to 100A. Their warranty covers this.

 i can see the problems. If you can measure the voltage from the battery into the inverter during the time the inverter does not detect the battery. Also check the battery LED on the inverter. It should be on if a battery is connected. I would also look at the real time values with EzManage. Do they align with SEMS. Another test you can do during the time the inverter ignores the battery at night is to simulate a grid failure and check if you have power on the back up output.  

Just had another idea. Shut down and restart the inverter and see if it fixes the problems. All your findings will help Goodwe and Revov to hopefully find and fix the problems

 

22 minutes ago, Fuenkli said:

the charge voltages are a bit high. According to the Revov spec I found on the web bulk and float should be 54.4

https://www.sustainable.co.za/revov-2nd-life-200ah-10-2kwh-lifepo4-battery.html

Also check the battery capacity in EzManage or PV Master. It should be 200Ah. 

I would also lower the discharge depth to 90% and increase the charge current to 100A. Their warranty covers this.

 i can see the problems. If you can measure the voltage from the battery into the inverter during the time the inverter does not detect the battery. Also check the battery LED on the inverter. It should be on if a battery is connected. I would also look at the real time values with EzManage. Do they align with SEMS. Another test you can do during the time the inverter ignores the battery at night is to simulate a grid failure and check if you have power on the back up output.  

Just had another idea. Shut down and restart the inverter and see if it fixes the problems. All your findings will help Goodwe and Revov to hopefully find and fix the problems

I thank you again for the input. I have no idea what half of it means 🙂 

AIUI, discharge depth controls how far the battery will discharge before the system resorts to mains. I'm comfortable with this at 60% because, as you will see in the graphs, the system takes a knock at 4:30 in the morning when our heat pump turns on.

I take your point with measuring the voltage when the battery is not detected by the inverter, but I don't always know that it's happened. I only noticed the latest goings on when checking the portal whilst waiting at the barber this morning - my one break in a busy morning.

But I'll try to keep an eye on it.
 

Link to comment
Share on other sites

26 minutes ago, Fuenkli said:

Also check the battery LED on the inverter. It should be on if a battery is connected.

That LED goes off when the reported SOC suddenly drops to 0% (what I call battery being lost). I didn't check last night, and I have not seen that situation before - plenty of charge reported but system decides to draw from mains anyway.

Link to comment
Share on other sites

5 minutes ago, Bobster said:

AIUI, discharge depth controls how far the battery will discharge before the system resorts to mains. I'm comfortable with this at 60% because, as you will see in the graphs, the system takes a knock at 4:30 in the morning when our heat pump turns on.

Now I think about it, this doesn't make a lot of sense. Most days the battery would hit about 50% in the morning and then start charging from the panels. If there was no mains it would draw from the battery or solar anyway. 

My calculation is an attempt at a worst case scenario where the load shedding starts just as the sun is going down and I have to get through until sunrise. But really, with no grid, does it make a difference?

 

Link to comment
Share on other sites

4 hours ago, Bobster said:

But I'll try to keep an eye on it.

What I can see from this, after running a pretty high load for some time, the battery protects itself  by switching off. This can be caused by the voltage dropping to low during this time, The voltage the battery's needs to switch on again can only be reached by either waiting for PV or by resetting the system. 

Please post the graphs should it happen again, I am pretty sure it will happen again while running large load. 

SOC.thumb.PNG.7c02056d06a229acfa4a06ae82819d96.PNG

Link to comment
Share on other sites

57 minutes ago, Jaco de Jongh said:

What I can see from this, after running a pretty high load for some time, the battery protects itself  by switching off. This can be caused by the voltage dropping to low during this time, The voltage the battery's needs to switch on again can only be reached by either waiting for PV or by resetting the system. 

Please post the graphs should it happen again, I am pretty sure it will happen again while running large load. 

SOC.thumb.PNG.7c02056d06a229acfa4a06ae82819d96.PNG

Thanks Jaco. As i read that graph, it shows the battery not being used at all. The grid line (yellow) constantly mirtors the load. There was no draw from the battery for seversl hours. 

 

The large load you point out is the heat pump kicking in. It does that at the same time each morning. The battery loss is not always at a time of high load. 

Im posting the graph from 21st that shows the battery closing down in the evening when the load was not great. 

 

Screenshot_20191124_192020.jpg

Link to comment
Share on other sites

19 hours ago, Bobster said:

Most days the battery would hit about 50% in the morning

That is not possible with the 60% DOD settings you have published. If it indeed discharges past the 60% then there is something wrong with the inverter and I would take this up with Goodwe. 

Link to comment
Share on other sites

14 hours ago, Bobster said:

Im posting the graph from 21st that shows the battery closing down in the evening when the load was not great

to me it looks like a battery problem (or the connection from the battery to the inverter). Can you please generate the SEMS portal battery voltage report (see attached example)  for the 21 and publish it. 

 

battery voltage.JPG

Link to comment
Share on other sites

50 minutes ago, Fuenkli said:

That is not possible with the 60% DOD settings you have published. If it indeed discharges past the 60% then there is something wrong with the inverter and I would take this up with Goodwe. 

That setting is a bit backwards. 60% means you can consume 60% of the battery and the system starts drawing from the grid at 40%. So 40%, in my case, is the cushion that I have for load shedding.

Link to comment
Share on other sites

44 minutes ago, Fuenkli said:

to me it looks like a battery problem (or the connection from the battery to the inverter). Can you please generate the SEMS portal battery voltage report (see attached example)  for the 21 and publish it. 

 

battery voltage.JPG

Here you go. 

 

image.thumb.png.3b887683f44fdfcb89094982b118fda0.png

Edited by Bobster
Wrong attachment supplied previously
Link to comment
Share on other sites

21 hours ago, Fuenkli said:

the charge voltages are a bit high. According to the Revov spec I found on the web bulk and float should be 54.4

https://www.sustainable.co.za/revov-2nd-life-200ah-10-2kwh-lifepo4-battery.html

Also check the battery capacity in EzManage or PV Master. It should be 200Ah. 

I would also lower the discharge depth to 90% and increase the charge current to 100A. Their warranty covers this.

Thanks for all your time on  this.

Those look nothing like the revovs that I have. Neither does anything on their web site 😞 

Link to comment
Share on other sites

50 minutes ago, Bobster said:

That setting is a bit backwards. 60% means you can consume 60% of the battery and the system starts drawing from the grid at 40%. So 40%, in my case, is the cushion that I have for load shedding.

sorry my mistake. You are right. 

 

33 minutes ago, Bobster said:

Here you go. 

that basically confirms why the inverter reports 0% SOC after it detects no power on the battery input. At least we have narrowed it down a bit. It could still be either the inverter or the battery. The probability that it is the battery is however much higher. I propose to look into the battery first. I would send the graphs to Revov, let them access your station on the SEMS portal and demand action.

Link to comment
Share on other sites

24 minutes ago, Bobster said:

Those look nothing like the revovs that I have

Thats what bothers me about these 2nd Life batteries, it is whatever they can get their hands on, including BMS etc. 

I really hope they come to your aid, for the amount of money spent it is unacceptable to be in this situation.  

Link to comment
Share on other sites

1 hour ago, Fuenkli said:

sorry my mistake. You are right. 

 

that basically confirms why the inverter reports 0% SOC after it detects no power on the battery input. At least we have narrowed it down a bit. It could still be either the inverter or the battery. The probability that it is the battery is however much higher. I propose to look into the battery first. I would send the graphs to Revov, let them access your station on the SEMS portal and demand action.

Thanks.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...