solar query

[XLD]

I have 2 pairs of 100w panels. Each pair going through a separate MPPT.

One panel has died so I've put the good one in series with the the good pair. Do I need to disconnect the redundent MPPT from the batteries? I'll be replacing the dead panel next week.

[Alan de Enfield]

2 minutes ago, XLD said:

I have 2 pairs of 100w panels. Each pair going through a separate MPPT.

One panel has died so I've put the good one in series with the the good pair. Do I need to disconnect the redundent MPPT from the batteries? I'll be replacing the dead panel next week.

 

Check that the voltage / current of the three panels can be handled by the MPPT, or, you may get magic smoke.

If you have (say) 3 x 20 volt panels that's 60 volts in series, if the MPPT was bought to handle only 2x panels it could be only a 40 or 50 volt controller.

[PeterF]

Most modern / good quality MPPT controllers do not allow reverse current flow through the panels so you should be OK, but it is not absolutely a given. The easiest option, assuming that you have them wired up correctly is to remove the fuse in the positive line between the MPPT and the battery. Then put the fuse back in before you connect the new panel.

[Tony Brooks]

29 minutes ago, PeterF said:

Most modern / good quality MPPT controllers do not allow reverse current flow through the panels so you should be OK, but it is not absolutely a given. The easiest option, assuming that you have them wired up correctly is to remove the fuse in the positive line between the MPPT and the battery. Then put the fuse back in before you connect the new panel.

 

I think that might be confusing. Taking it as written it seems that the two panels will still be connected to the controller when the fuse is pulled out. Many controller instructions stress never have the batteries disconnected and the panel(s) connected.

[Alan de Enfield]

4 minutes ago, Tony Brooks said:

 

I think that might be confusing. Taking it as written it seems that the two panels will still be connected to the controller when the fuse is pulled out. Many controller instructions stress never have the batteries disconnected and the panel(s) connected.

 

 

Indeed - you must disconnect between the Panel and the MPPT.

 

NOT the MPPT and the battery.

[PeterF]

33 minutes ago, Tony Brooks said:

 

I think that might be confusing. Taking it as written it seems that the two panels will still be connected to the controller when the fuse is pulled out. Many controller instructions stress never have the batteries disconnected and the panel(s) connected.

Taking it as written, the failed string has had one panel removed (the good one), thus that string is no longer working, therefore good to pull the fuse. The question only asks about leaving the MPPT connected, reading between the lines that the panels are disconnected.

 

However, your caution is correct that the failed panel must be confirmed as being disconnected before pulling the fuse.

[XLD]

3 hours ago, Alan de Enfield said:

 

Check that the voltage / current of the three panels can be handled by the MPPT, or, you may get magic smoke.

If you have (say) 3 x 20 volt panels that's 60 volts in series, if the MPPT was bought to handle only 2x panels it could be only a 40 or 50 volt controller.

Both MPPTs are Episolar 40s. They used to handle 4 x 100w each until nearly all the panels failed (they turned out to be very poor quality although supplied by a well known company). I had to replace them but (long story) only managed to get 4 under guarantee. One of the old panels was still working till yesterday but is now dead. The strange thing now is  the 6x6v Trojans, wired for 12 v,  are down to 12.1v and although there's 53v coming in from the 3 panels there's only 0.4A! The MPPT that's disconnected from the panels, (but not the batteries) has the red light on, indicating low voltage. I'm confused but I think I had better disconnect it from the batteries.

 

[Tony Brooks]

1 hour ago, PeterF said:

Taking it as written, the failed string has had one panel removed (the good one), thus that string is no longer working, therefore good to pull the fuse. The question only asks about leaving the MPPT connected, reading between the lines that the panels are disconnected.

 

However, your caution is correct that the failed panel must be confirmed as being disconnected before pulling the fuse.

 

The OP said that he intended to connect three panels in series, presumably leaving one MPPT disconnected. That means he should ensure the batteries are connected to the MPPT before he finally connects the three panels. He may have meant leaving the two in parallel and adding the third in series with them, or he might have meant he intended to wire all three in series but whatever he meant the panels shouldnever be left connected with the battereis disconnected.

[Alan de Enfield]

1 hour ago, XLD said:

Both MPPTs are Episolar 40s. They used to handle 4 x 100w each until nearly all the panels failed (they turned out to be very poor quality although supplied by a well known company). I had to replace them but (long story) only managed to get 4 under guarantee. One of the old panels was still working till yesterday but is now dead. The strange thing now is  the 6x6v Trojans, wired for 12 v,  are down to 12.1v and although there's 53v coming in from the 3 panels there's only 0.4A! The MPPT that's disconnected from the panels, (but not the batteries) has the red light on, indicating low voltage. I'm confused but I think I had better disconnect it from the batteries.

 

 

I don't think you are understanding my post, and it looks like you are not charging the batteries via your new 3-in-series panels. How were the original 4 connected ?
Series or parallel or series / parallel ?

 

An MPPT has two criteria to which it will work :

1) a maximum current it will accept

2) a maximum voltage it will work with.

 

You previously had 2 panels connected in series giving voltage of 2x the individual panel voltage, many 12 volt solar oanels are actually 19v. Now if your MPPT controler was bought at the same time and 'matched to the 2x 19v panels, it is probably either a 40 volt or a 50 volt MPPT controler.

 

NOW - you have added anothe panel in series so your output from the panels is now 3x the panel voltage so using the above figures the voltage now going into the 40 or 50 volt MPPT is now 60 volt - Magic smoke released.

 

YOU need to check 

1) The indivudual panel voltage and multiply by 3x

2) Look at the MPPT and see what the maximum voltage is.

 

if the result from '2' is greater than 3x result '1' its all hunky dory, if it is not then disconnect the third panel.

 

(Just as an indication my panels are 120 volt and my MPPT is 150 volt).

Edited July 15, 2022 by Alan de Enfield

[PeterF]

29 minutes ago, Tony Brooks said:

 

The OP said that he intended to connect three panels in series, presumably leaving one MPPT disconnected. That means he should ensure the batteries are connected to the MPPT before he finally connects the three panels. He may have meant leaving the two in parallel and adding the third in series with them, or he might have meant he intended to wire all three in series but whatever he meant the panels shouldnever be left connected with the battereis disconnected.

The OP said "I've I've put the good one in series...." , i.e. I have as in the past tense, not "I will" or "can I" or "should I" so the deed was done, it was not an intention.

[XLD]

12 hours ago, Alan de Enfield said:

 

I don't think you are understanding my post, and it looks like you are not charging the batteries via your new 3-in-series panels. How were the original 4 connected ?
Series or parallel or series / parallel ?

 

An MPPT has two criteria to which it will work :

1) a maximum current it will accept

2) a maximum voltage it will work with.

 

You previously had 2 panels connected in series giving voltage of 2x the individual panel voltage, many 12 volt solar oanels are actually 19v. Now if your MPPT controler was bought at the same time and 'matched to the 2x 19v panels, it is probably either a 40 volt or a 50 volt MPPT controler.

 

NOW - you have added anothe panel in series so your output from the panels is now 3x the panel voltage so using the above figures the voltage now going into the 40 or 50 volt MPPT is now 60 volt - Magic smoke released.

 

YOU need to check 

1) The indivudual panel voltage and multiply by 3x

2) Look at the MPPT and see what the maximum voltage is.

 

if the result from '2' is greater than 3x result '1' its all hunky dory, if it is not then disconnect the third panel.

 

(Just as an indication my panels are 120 volt and my MPPT is 150 volt).

 

12 hours ago, Alan de Enfield said:

 

I don't think you are understanding my post, and it looks like you are not charging the batteries via your new 3-in-series panels. How were the original 4 connected ?
Series or parallel or series / parallel ?

 

An MPPT has two criteria to which it will work :

1) a maximum current it will accept

2) a maximum voltage it will work with.

 

You previously had 2 panels connected in series giving voltage of 2x the individual panel voltage, many 12 volt solar oanels are actually 19v. Now if your MPPT controler was bought at the same time and 'matched to the 2x 19v panels, it is probably either a 40 volt or a 50 volt MPPT controler.

 

NOW - you have added anothe panel in series so your output from the panels is now 3x the panel voltage so using the above figures the voltage now going into the 40 or 50 volt MPPT is now 60 volt - Magic smoke released.

 

YOU need to check 

1) The indivudual panel voltage and multiply by 3x

2) Look at the MPPT and see what the maximum voltage is.

 

if the result from '2' is greater than 3x result '1' its all hunky dory, if it is not then disconnect the third panel.

 

(Just as an indication my panels are 120 volt and my MPPT is 150 volt).

20.2Vmp and 4.95A

 

12 hours ago, Alan de Enfield said:

 

I don't think you are understanding my post, and it looks like you are not charging the batteries via your new 3-in-series panels. How were the original 4 connected ?
Series or parallel or series / parallel ?

 

An MPPT has two criteria to which it will work :

1) a maximum current it will accept

2) a maximum voltage it will work with.

 

You previously had 2 panels connected in series giving voltage of 2x the individual panel voltage, many 12 volt solar oanels are actually 19v. Now if your MPPT controler was bought at the same time and 'matched to the 2x 19v panels, it is probably either a 40 volt or a 50 volt MPPT controler.

 

NOW - you have added anothe panel in series so your output from the panels is now 3x the panel voltage so using the above figures the voltage now going into the 40 or 50 volt MPPT is now 60 volt - Magic smoke released.

 

YOU need to check 

1) The indivudual panel voltage and multiply by 3x

2) Look at the MPPT and see what the maximum voltage is.

 

if the result from '2' is greater than 3x result '1' its all hunky dory, if it is not then disconnect the third panel.

 

(Just as an indication my panels are 120 volt and my MPPT is 150 volt).

Hi thanks for your info. The controllers are EpSolar 40 model (100 V & 40 Amp max) the panels are 20.2Vmp & 4.95A max. Originally I ran 4 panels in series/parallel on each controller, until they packed in. Then it was 2 in series to each controller. At the moment it's 3 in series to one controller, so that's 60.6v & 14.85A max. So should be OK. I've disconnected the other controller till I fit the new panel, then it's back to   2 x 2 panels (each pair in series) through 2 MPPTs.

Edited July 16, 2022 by XLD

[Alan de Enfield]

11 minutes ago, XLD said:

Hi thanks for your info. The controllers are EpSolar 40 model (100 V & 40 Amp max) the panels are 20.2Vmp & 4.95A max. Originally I ran 4 panels in series/parallel on each controller, until they packed in. Then it was 2 in series to each controller. At the moment it's 3 in series to one controller, so that's 60.6v & 14.85A max. So should be OK. I've disconnected the other controller till I fit the new panel, then it's back to   2 x 2 panels (each pair in series) through 2 MPPTs.

 

As you were - Its all good then.

[Richard10002]

19 hours ago, XLD said:

I have 2 pairs of 100w panels. Each pair going through a separate MPPT.

One panel has died so I've put the good one in series with the the good pair. Do I need to disconnect the redundent MPPT from the batteries? I'll be replacing the dead panel next week.

 

Deleted

Edited July 16, 2022 by Richard10002
already answered

[PineappleGuy]

10 hours ago, XLD said:

 

20.2Vmp and 4.95A

 

Hi thanks for your info. The controllers are EpSolar 40 model (100 V & 40 Amp max) the panels are 20.2Vmp & 4.95A max. Originally I ran 4 panels in series/parallel on each controller, until they packed in. Then it was 2 in series to each controller. At the moment it's 3 in series to one controller, so that's 60.6v & 14.85A max. So should be OK. I've disconnected the other controller till I fit the new panel, then it's back to   2 x 2 panels (each pair in series) through 2 MPPTs.

In series it's 4.95A not 14.85A. The output of the MPPT could be up to 20A (@14+ volts) so within the spec of the MPPT.

[XLD]

3 hours ago, PineappleGuy said:

In series it's 4.95A not 14.85A. The output of the MPPT could be up to 20A (@14+ volts) so within the spec of the MPPT.

👍

[XLD]

Still got this problem. 60v but only 0.4A going into the MPPT. Batteries down to 12.1v! Why is the amperage so low?

Edited July 17, 2022 by XLD

[Tony Brooks]

27 minutes ago, XLD said:

Still got this problem. 60v but only 0.4A going into the MPPT. Batteries down to 12.1v! Why is the amperage so low?

Is one of the panels reverse connected? 12V panels typically have an open circuit voltage of a bit over 20V whereas domestic ones can be much higher, but  3 panels in series would suggest 60V for 12V panels but 90V plus for domestic ones. I agree it is a mystery. Have you tried the other controller in case it is a controller fault. All just pondering.

[Alan de Enfield]

Thinking at a bit of a tangent - I had a weird problem that solar wasn't actually charging and the battery voltage was dropping.

 

Long story short (after talking it thru with Bimble) it was an easy fix.

 

I had been messing about with batteries and had accidently disconnected the controller output lead from the battery (big mistake as this can burn out the MPPT- you must always diconnect the solar panel to MPPT lead before disconnecting the MPPT lead to battery)

 

But, instead of burning out, the MPPT had lost its 'knowledge' of the batteries and had re-set itself to 24 volts.

 

I had to disconnect the panel to MPPT lead, then disconnect the battery to MPPT lead, wait 30+ seconds and then reconnect the BATTERY TO MPPT lead, then reconnect the PANEL TO MPPT lead and the system reset itself.

 

When you were disconnecting and moving panels about did you touch or even loosen the MPPT to battery wires ?

[XLD]

1 hour ago, Alan de Enfield said:

Thinking at a bit of a tangent - I had a weird problem that solar wasn't actually charging and the battery voltage was dropping.

 

Long story short (after talking it thru with Bimble) it was an easy fix.

 

I had been messing about with batteries and had accidently disconnected the controller output lead from the battery (big mistake as this can burn out the MPPT- you must always diconnect the solar panel to MPPT lead before disconnecting the MPPT lead to battery)

 

But, instead of burning out, the MPPT had lost its 'knowledge' of the batteries and had re-set itself to 24 volts.

 

I had to disconnect the panel to MPPT lead, then disconnect the battery to MPPT lead, wait 30+ seconds and then reconnect the BATTERY TO MPPT lead, then reconnect the PANEL TO MPPT lead and the system reset itself.

 

When you were disconnecting and moving panels about did you touch or even loosen the MPPT to battery wires ?

Interesting. Got to be worth a try. I'll let you know👍

[XLD]

2 hours ago, Alan de Enfield said:

Thinking at a bit of a tangent - I had a weird problem that solar wasn't actually charging and the battery voltage was dropping.

 

Long story short (after talking it thru with Bimble) it was an easy fix.

 

I had been messing about with batteries and had accidently disconnected the controller output lead from the battery (big mistake as this can burn out the MPPT- you must always diconnect the solar panel to MPPT lead before disconnecting the MPPT lead to battery)

 

But, instead of burning out, the MPPT had lost its 'knowledge' of the batteries and had re-set itself to 24 volts.

 

I had to disconnect the panel to MPPT lead, then disconnect the battery to MPPT lead, wait 30+ seconds and then reconnect the BATTERY TO MPPT lead, then reconnect the PANEL TO MPPT lead and the system reset itself.

 

When you were disconnecting and moving panels about did you touch or even loosen the MPPT to battery wires ?

Was just about to try that but controller reading at the moment is 49v and 4A. As Pineapple Guy said, max Amps will be 4.95A as panels are in series, so maybe things are OK. We'll see what happens.

Edited July 17, 2022 by XLD

[Tony Brooks]

21 minutes ago, XLD said:

Was just about to try that but controller reading at the moment is 49v and 4A. As Pineapple Guy said, max Amps will be 4.95A as panels are in series, so maybe things are OK. We'll see what happens.

 

To clarify, is that 4 amps panel current or charging current? On those figures assuming panel current I would expect the charging current to a bit under 16 amps, depending upon state of battery charge, and that seem quite good to me.

[XLD]

24 minutes ago, Tony Brooks said:

 

To clarify, is that 4 amps panel current or charging current? On those figures assuming panel current I would expect the charging current to a bit under 16 amps, depending upon state of battery charge, and that seem quite good to me.

 47v & 4A going in, 15A going out (fridge on) 12.5v.

[Tony Brooks]

Just now, XLD said:

 47v & 4A going in, 15A going out (fridge on) 12.5v.

 

That sounds as if the MPPT is doing its job.

 

Now the 12.1 volts, could this be a cell or cells shorting in a battery and running them down overnight? Any local hot spots on the battery when undercharge, individual dry or excessively gassing cells?

[Alan de Enfield]

31 minutes ago, XLD said:

 47v & 4A going in, 15A going out (fridge on) 12.5v.

 

 

Just to confim and avoid confusion thats :

 

4 amps coming out of the panels and

15 amps coming out of the MPPT.

 

And, not 4 amps going into the batteries and 15 amps coming out of the batteries (due to the fridge etc working hard)

[XLD]

34 minutes ago, Tony Brooks said:

 

That sounds as if the MPPT is doing its job.

 

Now the 12.1 volts, could this be a cell or cells shorting in a battery and running them down overnight? Any local hot spots on the battery when undercharge, individual dry or excessively gassing cells?

I'll check.

5 minutes ago, Alan de Enfield said:

 

 

Just to confim and avoid confusion thats :

 

4 amps coming out of the panels and

15 amps coming out of the MPPT.

 

And, not 4 amps going into the batteries and 15 amps coming out of the batteries (due to the fridge etc working hard)

The former statement.