Jump to content

Too high solar charge to batteries???


Recommended Posts

I have recently installed a 3kva/2.4KW Open Range Solar inverter. My aim was to create a temporary backup system. Probably an Axpert brand. I have 2 X 105Ah (2 X 12V = 24V system) batteries, flooded lead acid. Before i installed the panels the utility line charged the batteries to about 28.2V and then floated at 27V until there was a load again.

To get max life on the batteries i made the following settings. Setting numbers on my inverter indicated as well:

1. Source priority is set to Solar

5. battery type is set to Flooded lead acid

11. Max utility charging is 30A (Default)

12. Voltage point back to utility is 24.5V (Dont want DOD to go below 50%)

13. Voltage point back to battery is 27V (Default)

26. Bulk charging voltage is 28.2

27. Floating charging voltage is 27V (Default)

29. Low DC cut-off voltage is 24V (Again to save the battery)

 

I notice that solar charges the battery up to 30.4V and then hovers there for quite a while until battery is required again. 

Is 30.4V too high to charge the batteries up to???

My solar charger can handle a max of 80V and 50A. I have two 415W canadian solar panels. Input Voltage ranges from 25V to about 40V as they are wired in parallel. Going to add another panel so that the battery is not utilised as often as it is now. My hope is that the solar will cover a max of 500W demand during the day. I have no way to check what amps are coming from the panel as the inverter only shows input voltage and not amps.

So my questions are:

1. Is 30.4V too high for the batteries when charged by solar

2. How else can i check what amps are delivered from the panels.

3. Other than the solar charger max of 80V and 50A, Is there any maximum for the number of Watts that can pushed to the inverter? I want to add a few panels and want to try and work out the ideal configuration without going too close to the maximums.

Any responses will be appreciated.

Link to post
Share on other sites
1 hour ago, Vani said:

5. battery type is set to Flooded lead acid

That should be USE. Otherwise, settings 26, 27, and 29 will be ignored, and will default to values you don't like.

 

1 hour ago, Vani said:

11. Max utility charging is 30A (Default)

Check the specifications for your battery modules. Usually lead acid should only be run at 0.15C, which is 0.15 x 105 = 16 A, use 20 A (closest allowed value).

1 hour ago, Vani said:

12. Voltage point back to utility is 24.5V (Dont want DOD to go below 50%)

With setting 29 at 24 V, the effective value for this will be 25.0 V (1 V higher). You might have to compromise a bit, e.g. 23.7 V cutoff, effective back-to-grid voltage 24.7 V.

1 hour ago, Vani said:

I notice that solar charges the battery up to 30.4V and then hovers there for quite a while until battery is required again. 

That's pretty high, and I don't know why.

1 hour ago, Vani said:

Is 30.4V too high to charge the batteries up to???

Depends on the battery. Trojans might be OK with it; most other brands will boil. Changing setting 05 to USE should fix this problem.

1 hour ago, Vani said:

My solar charger can handle a max of 80V and 50A.

I note that the 50 A is on the battery side, so this is 1250 W nominal.

1 hour ago, Vani said:

I have two 415W canadian solar panels. Input Voltage ranges from 25V to about 40V as they are wired in parallel. Going to add another panel so that the battery is not utilised as often as it is now. My hope is that the solar will cover a max of 500W demand during the day. I have no way to check what amps are coming from the panel as the inverter only shows input voltage and not amps.

Oh. I thought most models showed PV charging current (but is that total or net into the battery? never clear), and they all showed PV power. 

1 hour ago, Vani said:

So my questions are:

1. Is 30.4V too high for the batteries when charged by solar

Most likely, yes.

1 hour ago, Vani said:

2. How else can i check what amps are delivered from the panels.

Check the menus carefully; otherwise, at least when debugging, a DC clamp meter.

1 hour ago, Vani said:

3. Other than the solar charger max of 80V and 50A, Is there any maximum for the number of Watts that can pushed to the inverter?

Yes. 50 A x 25 V = 1250 W; you could "overclock" by about 20%, so 1250 x 1.2 = 1500 W. But that's absolute maximum. 4 415 W panels would be too much. Three of those giant panels is about right for your system.

Link to post
Share on other sites

1. I set the battery type to user defined and it seems to have solved my high voltage issue. It now reaches the default bulk charging voltage of 28.2V and does not go beyond that.

2. i am going to change the DC cut-off to your suggested 23.7 and monitor it from there

3. I have set the max utility charging to 20A which is the lowest on this unit.

4. No other info on the menus about PV current. I am going to try a DC clamp meter.

5. It was always my plan to go for one more 415W panel

Thanks very much for the information. Very helpful indeed.

Link to post
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...