Solar The Solar Panel Thread

[G Daddy]

Hi @Boots in Action , ( Any idea how much your 140w panel could be capable of when sun more favorably in position? ) I don't have a data sheet for this panel but remember seeing about 7 Amps when using them as a portable system PMW with a flattish battery. looking at several data sheets of current 140W panels ie below, presume 8.0A from panel multiplied by 20% for MPPT should give approx 8.6A in ideal conditions. Being mounted flat on the roof now I will have to wait until summer to see how close I get to this.
In regard to the 3.5Amps the batteries were not far of full charge.

 

[Bellbirdweb]

Hi @Bellbirdweb ,
in his previous post, he said it was a:

EPSolar EPEver Tracer A Series 30 Amp

cheers
Mike

Thanks, I tried to find it, but this is a long thread

 

[Boots in Action]

Hi @Boots in Action , In relation to temperature most panels have a coefficient of -0.2% / deg C to -0.5% / deg C
View attachment 56341
In relation to voltage drop across diodes, Silicon 0.6 to 0.7 V , Schottky 0.2 to 0.5 V

Hi @G Daddy , still doing testing at home and looking at connections on back of panels - all different too. Before going into diode set up for each panel, did a check on how temperature affects output today - very warm at 30C and bright cloudless skies.
First test on 200w panel " C". Ocv when cool straight from inside was 19.3v. Voltage steadily dropped as panel got hot (too hot to keep hand on back for long!) to 17.9v. However when testing short circuit current Isc, I obtained a reading of 9.45A and a lot of sparking too!!!
Second test under same conditions for 180w panel "B" was 21.5v OCV, dropping to 20.1v and 8.6A Isc.
Third test on 80w panel "A" was 22.1v dropping to 20.5v and Isc of 4.8A.
This really proves how much heat on the panel affects output!! @mikerezny , you were after these figures in an earlier thread.
Now to the panels and diode setups: Also for @mikerezny info.
Panel "C" seems to have two systems in EACH panel. It has three terminals in each box with all three terminals connected with 2 X 10A10 diodes forward biased from Neg terminal to Centre terminal then another diode from Centre term also forward biased to Pos terminal. Between Neg and centre terminal is over 9.5v potential and the same potential between centre term and Positive take off point.. So these to me look like blocking diodes . Panel "A" 80w is wired the same . Effectively 9.5v connected in series, (to give 19v) which is then connected in parallel with the same output from the other panel. What do you think of removing the two blocking diodes which would be causing a .7v drop at each point and replacing them with just one Schottky diode 15 A across the output terminals in parallel as a bypass in case one panel is in shade. I have read on one of your links that there is no need for blocking diodes if connecting in series as solar controller does the blocking action needed at night.
Your advice would be greatly appreciated .
The 180w panel "B" has only two terminals for each panel and just the one 10A10 silicon diode across the outputs in each panel - parallel connection so bypass type???Will probably replace with 20A Schottky diode.
Please advise further on this if you can.
I am going away again on Sunday and will have a great time rechecking all the preliminary data from last time. As I understand my MPPT controller more, I have discovered that it gives a readout of "panel power available" in watts before it is converted by the MPPT system. Should be a great few days in between cold drinks!!!

 

[mikerezny]

Hi @G Daddy , still doing testing at home and looking at connections on back of panels - all different too. Before going into diode set up for each panel, did a check on how temperature affects output today - very warm at 30C and bright cloudless skies.
First test on 200w panel " C". Ocv when cool straight from inside was 19.3v. Voltage steadily dropped as panel got hot (too hot to keep hand on back for long!) to 17.9v. However when testing short circuit current Isc, I obtained a reading of 9.45A and a lot of sparking too!!!
Second test under same conditions for 180w panel "B" was 21.5v OCV, dropping to 20.1v and 8.6A Isc.
Third test on 80w panel "A" was 22.1v dropping to 20.5v and Isc of 4.8A.
This really proves how much heat on the panel affects output!! @mikerezny , you were after these figures in an earlier thread.
Now to the panels and diode setups: Also for @mikerezny info.
Panel "C" seems to have two systems in EACH panel. It has three terminals in each box with all three terminals connected with 2 X 10A10 diodes forward biased from Neg terminal to Centre terminal then another diode from Centre term also forward biased to Pos terminal. Between Neg and centre terminal is over 9.5v potential and the same potential between centre term and Positive take off point.. So these to me look like blocking diodes . Panel "A" 80w is wired the same . Effectively 9.5v connected in series, (to give 19v) which is then connected in parallel with the same output from the other panel. What do you think of removing the two blocking diodes which would be causing a .7v drop at each point and replacing them with just one Schottky diode 15 A across the output terminals in parallel as a bypass in case one panel is in shade. I have read on one of your links that there is no need for blocking diodes if connecting in series as solar controller does the blocking action needed at night.
Your advice would be greatly appreciated .
The 180w panel "B" has only two terminals for each panel and just the one 10A10 silicon diode across the outputs in each panel - parallel connection so bypass type???Will probably replace with 20A Schottky diode.
Please advise further on this if you can.
I am going away again on Sunday and will have a great time rechecking all the preliminary data from last time. As I understand my MPPT controller more, I have discovered that it gives a readout of "panel power available" in watts before it is converted by the MPPT system. Should be a great few days in between cold drinks!!!

Hi @Boots in Action,
short answer, in case I can't reply before you go away for the weekend.

As far as I understand:
1: If you are using a single panel and any solar controller, you do not need either bypass or blocking diodes.

2: If you have two panels wired in series and an MPPT solar controller, to get some output when only one of the panels is in sunlight, you need to have bypass diodes in each panel. Note that in normal operation with both panels in sunlight, both diodes will be reverse biassed (off) and there is no need to worry about the forward voltage drop. The forward voltage drop across the diode only comes into play when one panel is in the shade. But that is not the normal situation, and I would think it is relatively unimportant whether the forward bias is either 0.7V or 0.3V in series with the panel which is in sunlight.

3: If you have two panels wired in parallel and any solar controller, to prevent a panel in shade from loading a panel in sunlight, you need to have a blocking diode in each panel. In this case, the forward voltage drop of the diode now more important since one diode is in series with each panel in normal operation or when one panel is in the shade.

Here is my take on your wiring. I might be wrong. When testing a single panel, if the voltage across the two diodes is the same as the output voltage, then they must be bypass diodes, and are reverse biassed in normal operation. If the voltage across the diode in normal operation is 0.7V then it is forward biassed and would be in series with the output, and thus a blocking diode.

4: If you have panels in series AND in parallel you should have bypass diodes on each cell and one blocking diode in each parallel string. A blocking diode is not needed in each panel.

Have a careful look at the panels with 2 diodes and three terminals. I think this could have one blocking diode and one bypass diode.
In this case the connecting wires would go to the outside lugs, BUT one of the solar cell outputs would go to the centre terminal, the other to one of the outer terminals. So, in effect, one diode is across the solar cells (bypass diode) and one diode goes from the centre terminal to the outer terminal (the one that is NOT connected to the solar cells) and is thus a blocking diode.

You can see this in the attached figure. Labelling the terminal (L to R) L, C, R
The cells are soldered at the top L and C, and the left diode is reverse biased across the solar cell (bypass).
The output is across L and R and the right diode is in series with the solar output on C and the panel output on R.

Can you take a photo of each of the terminal blocks showing clearly the diodes, the soldered connections to the solar cells, and the connections to the output cables?

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
short answer, in case I can't reply before you go away for the weekend.

As far as I understand:
1: If you are using a single panel and any solar controller, you do not need either bypass or blocking diodes.

2: If you have two panels wired in series and an MPPT solar controller, to get some output when only one of the panels is in sunlight, you need to have bypass diodes in each panel. Note that in normal operation with both panels in sunlight, both diodes will be reverse biassed (off) and there is no need to worry about the forward voltage drop. The forward voltage drop across the diode only comes into play when one panel is in the shade. But that is not the normal situation, and I would think it is relatively unimportant whether the forward bias is either 0.7V or 0.3V in series with the panel which is in sunlight.

3: If you have two panels wired in parallel and any solar controller, to prevent a panel in shade from loading a panel in sunlight, you need to have a blocking diode in each panel. In this case, the forward voltage drop of the diode now more important since one diode is in series with each panel in normal operation or when one panel is in the shade.

Here is my take on your wiring. I might be wrong. When testing a single panel, if the voltage across the two diodes is the same as the output voltage, then they must be bypass diodes, and are reverse biassed in normal operation. If the voltage across the diode in normal operation is 0.7V then it is forward biassed and would be in series with the output, and thus a blocking diode.

4: If you have panels in series AND in parallel you should have bypass diodes on each cell and one blocking diode in each parallel string. A blocking diode is not needed in each panel.

Have a careful look at the panels with 2 diodes and three terminals. I think this could have one blocking diode and one bypass diode.
In this case the connecting wires would go to the outside lugs, BUT one of the solar cell outputs would go to the centre terminal, the other to one of the outer terminals. So, in effect, one diode is across the solar cells (bypass diode) and one diode goes from the centre terminal to the outer terminal (the one that is NOT connected to the solar cells) and is thus a blocking diode.

You can see this in the attached figure. Labelling the terminal (L to R) L, C, R
The cells are soldered at the top L and C, and the left diode is reverse biased across the solar cell (bypass).
The output is across L and R and the right diode is in series with the solar output on C and the panel output on R.

Can you take a photo of each of the terminal blocks showing clearly the diodes, the soldered connections to the solar cells, and the connections to the output cables?

cheers
Mike
View attachment 56598

Thanks @mikerezny for your late night and full explanation. The picture you have sent is exactly the same set up as my two panels "A" an "C". Panel "B" is different and will send pictures of both for you to peruse today and advise. Can't seem to get my head around the fact that I have 9.5v across Neg term to centre tap and same voltage across centre tap to Pos term and yet have 19 volts across Neg to Pos terminals. Aren't bypass diodes supposed to be in parallel across the output terminals?? And shouldn't the blocking diode be in series with output???
Incidentally Panel "A" (80w) has 36 cells per panel - 9 down by 4 across, panel "B"(180w) has 72 cells per panel - 12 down by 6 across, and panel "C" (200w) has only 16 cells per panel - 4 down by 4 across albeit much larger square cells than the other two panels.

 

[mikerezny]

Thanks @mikerezny for your late night and full explanation. The picture you have sent is exactly the same set up as my two panels "A" an "C". Panel "B" is different and will send pictures of both for you to peruse today and advise. Can't seem to get my head around the fact that I have 9.5v across Neg term to centre tap and same voltage across centre tap to Pos term and yet have 19 volts across Neg to Pos terminals. Aren't bypass diodes supposed to be in parallel across the output terminals?? And shouldn't the blocking diode be in series with output???
Incidentally Panel "A" (80w) has 36 cells per panel - 9 down by 4 across, panel "B"(180w) has 72 cells per panel - 12 down by 6 across, and panel "C" (200w) has only 16 cells per panel - 4 down by 4 across albeit much larger square cells than the other two panels.

Hi @Boots in Action,
when you look at the connection box try to determine where the two leads are coming in from the actual solar cell array.
Then you should be able to draw, for each of your three panels, a circuit diagram that shows the cell array, diodes, and output terminals.

A typical solar cell outputs about 0.5V. So, I would suggest that:
panel A has all 36 cells in series which should give approximately 18Voc. If you put this panel out in the sun and cover one cell the output should drop to zero.

panel B, which has 72 cells could be wired with two parallel strings with each string consisting of 36 cells in series.
If this is the case, when you put the panel out in the sun and cover one cell, the output current should be halved.
OR: panel B consists of two half panels: each sub panel consists of 4 parallel strings, with each string consisting of 18 cells.
This would give about 9V per sub array.
If this is the case, you should see THREE wires coming from the cell array. Then both diodes would be wired bypass diodes.
That would seem to agree with the voltages you were measuring.

Hard to tell until I can see a picture of the junction box.

Hang on. How many actual panels are in what you are calling A, B, and C?
I have been assuming each of these is a single panel with a single junction box. If this is not the case, how are each of the individual panels wired together?

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
when you look at the connection box try to determine where the two leads are coming in from the actual solar cell array.
Then you should be able to draw, for each of your three panels, a circuit diagram that shows the cell array, diodes, and output terminals.

A typical solar cell outputs about 0.5V. So, I would suggest that:
panel A has all 36 cells in series which should give approximately 18Voc. If you put this panel out in the sun and cover one cell the output should drop to zero.

panel B, which has 72 cells could be wired with two parallel strings with each string consisting of 36 cells in series.
If this is the case, when you put the panel out in the sun and cover one cell, the output current should be halved.
OR: panel B consists of two half panels: each sub panel consists of 4 parallel strings, with each string consisting of 18 cells.
This would give about 9V per sub array.
If this is the case, you should see THREE wires coming from the cell array. Then both diodes would be wired bypass diodes.
That would seem to agree with the voltages you were measuring.

Hard to tell until I can see a picture of the junction box.

Hang on. How many actual panels are in what you are calling A, B, and C?
I have been assuming each of these is a single panel with a single junction box. If this is not the case, how are each of the individual panels wired together?

cheers
Mike

Hi @mikerezny , I think I may have confused you. All three solar systems consist of TWO panels which fold together on to one another for transportation. Refer my earlier thread show setup in the Connondales for first test. So I have six (6) panels all up which consist of matched pairs. Each pair of panels are connected in PARALLEL, so that is not the hassle I am sure. Photos of connection boxes for each pair of panels will be sent shortly.

 

[Boots in Action]

Hi @mikerezny , I think I may have confused you. All three solar systems consist of TWO panels which fold together on to one another for transportation. Refer my earlier thread show setup in the Connondales for first test. So I have six (6) panels all up which consist of matched pairs. Each pair of panels are connected in PARALLEL, so that is not the hassle I am sure. Photos of connection boxes for each pair of panels will be sent shortly.

Hi @mikerezny , here are the photos of rear connection boxes of all three PAIRS of panels. Photos 1 and 2 are for Panel "A" which is rated at 80w (2 X 40w). Photos 3 and 4 are for panel "B" which is rated at 180w (2 X 90w) . Photos 5 and 6 are for panel "C" rated at 200w (100 X 2). Connections for photos 1,2,5 and 6 are similar with 3 terminals connected by 2 diodes. (suggest these are blocking diodes). Photos 3 and 4 show "B" panel with only TWO terminals - the centre one is NOT connected to any panel line and has 2 X 10A10 diodes IN SERIES connected ACROSS the output lines on EACH panel where both outputs are connected in PARALLEL. What can you tell me please. (bypass circuit?)
Ocv for EACH panel individually was 21.5v, 21.4v and 19.5v. Will now go and test each one with blanket covering each half (of each pair) and see what that shows up.

 

[mikerezny]

Hi @mikerezny , I think I may have confused you. All three solar systems consist of TWO panels which fold together on to one another for transportation. Refer my earlier thread show setup in the Connondales for first test. So I have six (6) panels all up which consist of matched pairs. Each pair of panels are connected in PARALLEL, so that is not the hassle I am sure. Photos of connection boxes for each pair of panels will be sent shortly.

Hi @Boots in Action,
ok, thanks for clarifying that. I do now remember the solar farm you had set up.

That bring up a VERY interesting point. All three of your systems consist of pairs of panels.
In the following, to avoid confusion, I will stick to A, B, an
So, why not take the following approach to optimising your solar setup AND reducing the complexity and increasing the flexibility.

First step, for each of your solar panels, A, B, and C: rewire them to be always in series instead of parallel.
On each of the two subpanels, ensure you fit a bypass diode. Depending on the arrangement of cells within a subpanel, you may already have bypass diodes.
Now you have 3 panels A, B, and C. Each having two exactly matching subpanels wired in series.

Now make sure each panel has only ONE blocking diode.

Now you have 3 panels, A, B, and C that can be connected in parallel in an any combination.

Does this make sense?

I will look at the photos in more detail.

cheers
Mike

 

[mikerezny]

Hi @mikerezny , here are the photos of rear connection boxes of all three PAIRS of panels. Photos 1 and 2 are for Panel "A" which is rated at 80w (2 X 40w). Photos 3 and 4 are for panel "B" which is rated at 180w (2 X 90w) . Photos 5 and 6 are for panel "C" rated at 200w (100 X 2). Connections for photos 1,2,5 and 6 are similar with 3 terminals connected by 2 diodes. (suggest these are blocking diodes). Photos 3 and 4 show "B" panel with only TWO terminals - the centre one is NOT connected to any panel line and has 2 X 10A10 diodes IN SERIES connected ACROSS the output lines on EACH panel where both outputs are connected in PARALLEL. What can you tell me please. (bypass circuit?)
Ocv for EACH panel individually was 21.5v, 21.4v and 19.5v. Will now go and test each one with blanket covering each half (of each pair) and see what that shows up.

Hi @Boots in Action,
Panel B, as you said, for each subpanel, has two diodes in series across the entire subpanel, wired as 21.4V.
Panels A, and C, have each subpanel split into two sections which are wired in series. Hence the three wires you can see coming in at the top of each junction box. The is a bypass diode across each of the two panel sections. Each section will be delivering about 9.5V.

So, the best I can suggest is to rewire, for Panels, A, B, and C, each subpanel in series instead of parallel.
All panels will have the required bypass diodes. You can use the supplied diodes with no problem, as per my previous post.

If you decide to do that. Then we can discuss how to use the panels in Parallel and add blocking diodes.

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
Panel B, as you said, for each subpanel, has two diodes in series across the entire subpanel, wired as 21.4V.
Panels A, and C, have each subpanel split into two sections which are wired in series. Hence the three wires you can see coming in at the top of each junction box. The is a bypass diode across each of the two panel sections. Each section will be delivering about 9.5V.

So, the best I can suggest is to rewire, for Panels, A, B, and C, each subpanel in series instead of parallel.
All panels will have the required bypass diodes. You can use the supplied diodes with no problem, as per my previous post.

If you decide to do that. Then we can discuss how to use the panels in Parallel and add blocking diodes.

cheers
Mike

Hi @mikerezny , on the ball there!! What a great idea. I too like the KISS principal!! What I really want to do is only use panels "B" and "C" in series as I was getting over 15 A with this arrangement, However, your idea of wiring these two types of panels (actually 4 solar panels) in series is a good Idea. Panel "B" (180w) has been measured at 21.5 v OCV and at least 8.0A whilst panel "C" has been measured at 19.5v Ocv and at least 9A. If EACH INDIVIDUAL panel is connected in series as one string, I should in theory be getting somewhere around 70 volts at 4A minimum - a total of 280 watts. If the MPPT controller converted this to say 12.8 volts, I am talking about 20 odd amperes. Is this calculation correct?? Would have to upgrade blocking and bypass diodes to 30 amp rating wouldn't I?? Please continue as I am on a roll!!!

 

[mikerezny]

Hi @mikerezny , here are the photos of rear connection boxes of all three PAIRS of panels. Photos 1 and 2 are for Panel "A" which is rated at 80w (2 X 40w). Photos 3 and 4 are for panel "B" which is rated at 180w (2 X 90w) . Photos 5 and 6 are for panel "C" rated at 200w (100 X 2). Connections for photos 1,2,5 and 6 are similar with 3 terminals connected by 2 diodes. (suggest these are blocking diodes). Photos 3 and 4 show "B" panel with only TWO terminals - the centre one is NOT connected to any panel line and has 2 X 10A10 diodes IN SERIES connected ACROSS the output lines on EACH panel where both outputs are connected in PARALLEL. What can you tell me please. (bypass circuit?)
Ocv for EACH panel individually was 21.5v, 21.4v and 19.5v. Will now go and test each one with blanket covering each half (of each pair) and see what that shows up.

Hi @Boots in Action,
The subpanels for both panels A and B are definitely in parallel.

Each of the subpanels for panel C have only two wires leaving the junction box. What happens to these wires on their way to your connector?

cheers
Mike

 

[mikerezny]

Hi @mikerezny , on the ball there!! What a great idea. I too like the KISS principal!! What I really want to do is only use panels "B" and "C" in series as I was getting over 15 A with this arrangement, However, your idea of wiring these two types of panels (actually 4 solar panels) in series is a good Idea. Panel "B" (180w) has been measured at 21.5 v OCV and at least 8.0A whilst panel "C" has been measured at 19.5v Ocv and at least 9A. If EACH INDIVIDUAL panel is connected in series as one string, I should in theory be getting somewhere around 70 volts at 4A minimum - a total of 280 watts. If the MPPT controller converted this to say 12.8 volts, I am talking about 20 odd amperes. Is this calculation correct?? Would have to upgrade blocking and bypass diodes to 30 amp rating wouldn't I?? Please continue as I am on a roll!!!

Hi @Boots in Action,
not quite what I meant.

What is the maximum input voltage for your MPPT controller? You may find your controller won't handle voltages that high.

My suggestion is to separately rewire each of you panels, A, B, and C, to be in series instead of parallel.

Then you will have three panels all at about 39V. But the great thing is that each panel has two identical panels in series.
All panels already have bypass diodes.

Now, after that is done, you can easily connect any of the panels in parallel.
But you will have to think about how to add the blocking diodes.
Perhaps a small connector box that has two/three andersons on the input side for your solar panels and one anderson on the output side heading off to the MPPT controller. Inside the junction box join all the black wires together, but put a Shotkey diode in series with each red input wire and join all the other side of the diodes to the red wire going to the controller.
This has the advantage that if you us only one panel, you don't use the junction box and thus have no blocking diode in series wasting energy. The spec sheet for the diodes you currently have show a voltage drop close to 1V for the sort of current you are generating here.

Is this any clearer?

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
The subpanels for both panels A and B are definitely in parallel.

Each of the subpanels for panel C have only two wires leaving the junction box. What happens to these wires on their way to your connector?

cheers
Mike

Hi @mikerezny , the output wires for each sub panel for panel "C" are connected in parallel into a common Anderson plug for connection to lead to go to van.

 

[Boots in Action]

Hi @Boots in Action,
not quite what I meant.

What is the maximum input voltage for your MPPT controller? You may find your controller won't handle voltages that high.

My suggestion is to separately rewire each of you panels, A, B, and C, to be in series instead of parallel.

Then you will have three panels all at about 39V. But the great thing is that each panel has two identical panels in series.
All panels already have bypass diodes.

Now, after that is done, you can easily connect any of the panels in parallel.
But you will have to think about how to add the blocking diodes.
Perhaps a small connector box that has two/three andersons on the input side for your solar panels and one anderson on the output side heading off to the MPPT controller. Inside the junction box join all the black wires together, but put a Shotkey diode in series with each red input wire and join all the other side of the diodes to the red wire going to the controller.
This has the advantage that if you us only one panel, you don't use the junction box and thus have no blocking diode in series wasting energy. The spec sheet for the diodes you currently have show a voltage drop close to 1V for the sort of current you are generating here.

Is this any clearer?

cheers
Mike

Hi @mikerezny , thanks again for the ideas and info.
Firstly my MPPT controller can handle up to 100 volts at 25C. At lower temps, voltage will increase, so a safety factor of 10 to 15% will more than cover it as it is not that cold up here when sun is shining!!!
I am already running panels "B" and "C" in series and there is never a problem with connections as I have several good cables of various lengths with Anderson plugs, some wired for series connections and others for parallel connections. I also have a connector with two Anderson plugs to one Anderson plug or vice versa but that is set up for parallel connection.
I always have to fall back to the problem that putting two DISSIMILIAR panels in series will give me the average total voltage of both, with current limited to that of smallest panel output. Hence not using Panel "A" (80w). At present, I can run individual panels or at least two in series or parallel with the leads and connectors I have.
Thanks for the info on the existing diodes 10A10 which are currently in place. I was aware that they are a general purpose type and had a higher forward voltage drop than the Schottky type. That is why I am going to change most of them for 20A Schottky type as soon as I can in conjunction with your advice and ideas. I have the time and the Schottky are reasonably cheap from China and easy to solder into position.

Going back to my previous thread, are my calculations correct in theory ie 70 v approx at lowest sub panel output say 4A giving panel power of 280 watts, convert-able to 12.8 volts at approx 20 amps by my MPPT controller. If you think this is correct, I will give it a try but need advice regarding suggested required amperage level for Schottky diodes for the current produced. Your technical help is really appreciated I can tell you!! The results will be a guide for others on this forum I hope.

 

[mikerezny]

Hi @mikerezny , the output wires for each sub panel for panel "C" are connected in parallel into a common Anderson plug for connection to lead to go to van.

Hi @Boots in Action,
Good! So both subpanels in each panel are connected in parallel.

What is not currently good is that none of your subpanels has blocking diodes. That means that if one of the subpanels is in the shade it will then become a load on the other panel. You should be able tio see this when you cover one panel up. If this is correct, then you should see the panel current drop to less than half.

You could easily do an experiment with say panel A. On the subpanel that does not connect both panels, take on of the wires of the terminal. Now put both panels in the sun, but put a blanket over the panel you have disconnected. You will only be getting power from the other panel. Take the input power measurement, now connect the shaded panel and you should see a drop in input power.

Strange, isn't it, that all the panels have bypass diodes that would only be used if the panel was connected in series with another panel. And that would be done only rarely.

This is a great exercise. I had no idea this would become such an important learning opportunity.

I have been testing my setup today. I have a NiMh smart charger that individually charges 4 AA/AAA batteries. The good thing about this charger is that it runs off 12V. So I have been charging all our NiMh batteries today from the Penguin battery and our 40W solar panel.

The solar charger, is quite good. It bulk charges to 14.4V then settles down to 13.8V.
I now have the data sheet for my Ritar RA12-100 DG Gel battery. It recommends 14.2 - 14.4 for equalization and cycling and 13.6 - 13.8V for float charging. Specs are for 25C. So the charger is charging within the specs for the battery.

Although it is rated as a 100Ah battery it is really only a 88.6Ah battery on a 10h discharge to 10.8V at 8.86A. But on a 20h discharge at 4.56A it has a 91.2Ah capacity.

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
Good! So both subpanels in each panel are connected in parallel.

What is not currently good is that none of your subpanels has blocking diodes. That means that if one of the subpanels is in the shade it will then become a load on the other panel. You should be able tio see this when you cover one panel up. If this is correct, then you should see the panel current drop to less than half.

You could easily do an experiment with say panel A. On the subpanel that does not connect both panels, take on of the wires of the terminal. Now put both panels in the sun, but put a blanket over the panel you have disconnected. You will only be getting power from the other panel. Take the input power measurement, now connect the shaded panel and you should see a drop in input power.

Strange, isn't it, that all the panels have bypass diodes that would only be used if the panel was connected in series with another panel. And that would be done only rarely.

This is a great exercise. I had no idea this would become such an important learning opportunity.

I have been testing my setup today. I have a NiMh smart charger that individually charges 4 AA/AAA batteries. The good thing about this charger is that it runs off 12V. So I have been charging all our NiMh batteries today from the Penguin battery and our 40W solar panel.

The solar charger, is quite good. It bulk charges to 14.4V then settles down to 13.8V.
I now have the data sheet for my Ritar RA12-100 DG Gel battery. It recommends 14.2 - 14.4 for equalization and cycling and 13.6 - 13.8V for float charging. Specs are for 25C. So the charger is charging within the specs for the battery.

Although it is rated as a 100Ah battery it is really only a 88.6Ah battery on a 10h discharge to 10.8V at 8.86A. But on a 20h discharge at 4.56A it has a 91.2Ah capacity.

cheers
Mike

Hello @mikerezny , YOU think that you are learning a lot. I can tell you I am learning a LOT more thanks to you!!! Keep it up and we will BOTH become experts....well maybe a little bit more conversant with solar charging and MPPT controllers!!.

 

[mikerezny]

Hi @Boots in Action,
it seems like you are mainly interested in getting the best performance out of panels A and B. If that is correct, I have a fewquestions?

In your eventual setup where will these panels be mounted?

I know you have an MPPT solar controller. Is that the only solar controller you have?

In doing performance testing of the panels, it is imperative that the controller's battery charging function does not limit the output current. The only way I can see to do this is to ensure you have a load on the battery that is always higher than the current output from the controller. Have you some headlight lamps or anything else around that you can put across the battery to provide enough load?

Or, if you have a Dometic three-way fridge, and you have it connected to the tug via an Anderson plug, can you use that? It draws 15A, so it should be enough.

cheers
Mike

 

[Boots in Action]

Hi @Boots in Action,
it seems like you are mainly interested in getting the best performance out of panels A and B. If that is correct, I have a fewquestions?

In your eventual setup where will these panels be mounted?

I know you have an MPPT solar controller. Is that the only solar controller you have?

In doing performance testing of the panels, it is imperative that the controller's battery charging function does not limit the output current. The only way I can see to do this is to ensure you have a load on the battery that is always higher than the current output from the controller. Have you some headlight lamps or anything else around that you can put across the battery to provide enough load?

Or, if you have a Dometic three-way fridge, and you have it connected to the tug via an Anderson plug, can you use that? It draws 15A, so it should be enough.

cheers
Mike

Hi @mikerezny , what a day of exchanges, getting as bad as @aspiremr !!! But we are making progress.
In answer to your questions, I can provide the following:
I am mainly interested in getting the most out of panels "B" and "C". - 180w and 200w respectively. Panel "A" is only 80w but very efficient.
My setup of panels will be (normally) in full sun for most of the day. I have a 10 meter cable (8mm) available if necessary to get full sun.
I still have my other PWM controller - a 20A Powertech- which has full displays and is rather sophisticated (but not as detailed as my MPPT. )
I also have another basic 10A PWM which came with latest panel, but only shows charging in different stages ie 25%,50% etc.
I do have some 12 volt spotlights I could connect but like the idea of running my 3 way fridge on battery power for a short time during testing. Simple connections by using an Anderson plug to point on draw bar and other end from outlet/inlet Anderson plug which is wired directly across the battery terminals. That will mean it will NOT show as a load on my controller, but it will be noticeable as a lower voltage on controller before connecting panels. See my thread of 20th July for explanation 12/20??? Unfortunately, the Setec is also connected to this line at the draw bar (normally connected to my tug!!), so that would stuff things up a bit!!! Can't disconnect this either!!! Could see if I can remove side vent panel and connect directly to fridge terminals in there with alligator clips. Otherwise, might have to see what else I can hook up to create more draw - lights, fans, charging rechargeable lights and phones, Ipad etc. I have enough outlets!!!
Any further suggestions are most welcome.

 

[mikerezny]

My setup of panels will be (normally) in full sun for most of the day. I have a 10 meter cable (6mm) available if necessary to get full sun.

Hi @Boots in Action,
so both panels B and C will be portable. Nothing mounted on the roof of the Penguin?

Unfortunately, the Setec is also connected to this line at the draw bar (normally connected to my tug!!), so that would stuff things up a bit!!! Can't disconnect this either!!!

If I remember correctly, there is an inline blade fuse in the battery compartment on the red wire that goes to the Setec. Would removing that fix things. Or, remove the blade fuse for the battery in the Setec Fuse box.

cheers
Mike