An amp meter in one of the solar feeds, before connecting up the second one could confirm the flow is reversing because it has to be going somewhere
Solar The Solar Panel Thread
- Thread starter cruza driver
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Wiring to the TPS is correct, both positives to the positive solar in, both negatives in the negative solar in. Definitely wired parallel. Surely I have proved the wiring in both instances if I can disconnect one positive and see steady, correct amps at the TPS? This is how I charged the batteries each day - one morning I used the portable only, next morning the rooftop only, each time leaving wiring exactly the same apart from swapping out the positive at the TPS solar in. Both times I saw the ballpark amount of amps I expected from the individually-connected panels.
If I had a short in there somewhere, surely I wouldn't be able to do the above?
But agree, something isn't playing ball so will put my meter in to obtain amps and volts data separate to the controller to see if we can suss it out. Going away again this long weekend, this time at a powered site so can play around a bit without having to worry about missing out on battery top up time.
Appreciate the suggestions!
If I had a short in there somewhere, surely I wouldn't be able to do the above?
But agree, something isn't playing ball so will put my meter in to obtain amps and volts data separate to the controller to see if we can suss it out. Going away again this long weekend, this time at a powered site so can play around a bit without having to worry about missing out on battery top up time.
Appreciate the suggestions!
So did some testing today, bit overcast and afternoon so no steady current but enough to get some results (they just won't match directly between tests). Roof panel was partly shaded hence the low amps.
With TPS controller fully disconnected from all panels (+ and -): Roof Voc 20.0V, Isc 0.9A Portable Voc: 22.8V, Isc 11.8A Combined Voc 21.8V, Isc 13.85A Combined, with one of the two portable panels fully covered Voc 21.0V, Isc 6.24A
With TPS controller connected to each individual panel, similar results re current
With TPS controller connected to both portable and roof in parallel, briefly showed 8.0A on screen and meter then went to zero on both. Disconnecting and connecting in any combo could not repeat this, always went to zero amps after this when panels in parallel. Putting meter in series to portable showed -1.6A, meter in series with roof showed 6.2A.
Maybe it's just the TPS (PWM) doing what it's supposed to since all these tests were done when the batteries were pretty much full. I'll try and do a test where the panels are connected in parallel and I turn on a bunch of stuff (including the inverter with load) to force the TPS into Constant Power mode (ie full current from solar to batteries) and see if it pops up above zero.
With TPS controller fully disconnected from all panels (+ and -): Roof Voc 20.0V, Isc 0.9A Portable Voc: 22.8V, Isc 11.8A Combined Voc 21.8V, Isc 13.85A Combined, with one of the two portable panels fully covered Voc 21.0V, Isc 6.24A
With TPS controller connected to each individual panel, similar results re current
With TPS controller connected to both portable and roof in parallel, briefly showed 8.0A on screen and meter then went to zero on both. Disconnecting and connecting in any combo could not repeat this, always went to zero amps after this when panels in parallel. Putting meter in series to portable showed -1.6A, meter in series with roof showed 6.2A.
Maybe it's just the TPS (PWM) doing what it's supposed to since all these tests were done when the batteries were pretty much full. I'll try and do a test where the panels are connected in parallel and I turn on a bunch of stuff (including the inverter with load) to force the TPS into Constant Power mode (ie full current from solar to batteries) and see if it pops up above zero.
Hi @Fallen , that latest info points more and more to wrong leads connected to terminals on back of portable panel. Open up black plastic cover on junction box at back of panel and follow wires ("+" and "-" ) to where you have made the connection for the lead to the van. A negative reading (-1.6A ) on meter from portable is a sure sign that is where the problem lies or faulty diode?? I gather you do not get a negative reading on meter when connected in series with roof panel?? Please keep up the flow of testing.
So the panels in parallel are showing the expected VOC if i'm reading your post correctly so the wiring is ok.
I don't know if it is smart enough, but it could be starting and seeing too much current flow and disconnecting, or starting and seeing a sudden rise in battery voltage (over 14.7 from memory) and disconnecting. The TPS pulses the panel current into the batteries - a longer pulse gives higher current - until the battery voltage starts to rise, and then it shortens the pulses as the battery reaches 14.7. (You probably know this but thats where the PWM term comes from - Pulse Width Modulation). So it may try an initial pulse (the 8amps you mention), measure the battery voltage, and decide to stop further pulses/ charging.
Leaving it all hooked up and turning on a few lights to get the load up to 10 amps might test this. I would expect the TPS to start up to try and maintain 14.7V.
I don't know if it is smart enough, but it could be starting and seeing too much current flow and disconnecting, or starting and seeing a sudden rise in battery voltage (over 14.7 from memory) and disconnecting. The TPS pulses the panel current into the batteries - a longer pulse gives higher current - until the battery voltage starts to rise, and then it shortens the pulses as the battery reaches 14.7. (You probably know this but thats where the PWM term comes from - Pulse Width Modulation). So it may try an initial pulse (the 8amps you mention), measure the battery voltage, and decide to stop further pulses/ charging.
Leaving it all hooked up and turning on a few lights to get the load up to 10 amps might test this. I would expect the TPS to start up to try and maintain 14.7V.
The fact that one panel was showing -ve current is an indication that you need blocking diodes in series with each panel.
If you look inside the terminal box on each panel, are there any diodes in there?
If so, can you post photos of the terminal boxes. Thet will probably be wired as bypass diodes but you may be able to rewire them as bypass diodes.
cheers
Mike
If you look inside the terminal box on each panel, are there any diodes in there?
If so, can you post photos of the terminal boxes. Thet will probably be wired as bypass diodes but you may be able to rewire them as bypass diodes.
cheers
Mike
@mikerezny , normally the controllers have their own blocking diodes, thus preventing power loss from battery at night. I am sure the TPS would have this integrated into its circuit. It would appear that used individually through the TPS, there is no problem, but there appears to have a "bleed" back through the portable panel when both connected. That means there is higher resistance through TPS to battery than through the portable which should not conduct anyway. Causing a short circuit back to battery?? Interesting. I also want to see pictures of connections/diodes in junction box.
Hi.
A solar controller does indeed prevent the battery from discharging into a panel when there is no sun. But, when panels are wired in parallel, it does not prevent one panel in the sun from discharging into a panel that is not in the sun. Hence the need for blocking diodes.
This has been discussed in detail in previous posts. Otherwise do a Google on Blocking and Bypass diodes. Basically, bypass diodes in parallel across panels wired in series and blocking diodes in series with panels wired in parallel.
Ideally, all panels in parallel should have the same Voc.
cheers
Mike
Hi,
what is the maximum input current for the solar controller? A TP1230 is 35A if I am not mistaken. So if you have the same controller, it should not be a current overload.
cheers
Mike
what is the maximum input current for the solar controller? A TP1230 is 35A if I am not mistaken. So if you have the same controller, it should not be a current overload.
cheers
Mike
Agreed @mikerezny , I was really only thinking about the controller end. Not having any panels in parallel , only series in my set up, I did not consider your point. Bypass diodes are my only concern and I have that organised with the low loss Schottky type. Yes , all parallel panels should have same or close Voc and there is some difference in panel and portable outputs. I guess the lower voltage would tend to pull down higher voltage, and this was proven when both panels were connected in parallel in Voc readings. Notwithstanding all of the above, not enough to reduce current/voltage to zero. And also, your last post about specs for the TPS1230 is incorrect. Rating is 12 volts and 30 amps, so well within limitations of controller if working correctly. I think I would be looking to use another controller to eliminate controller defects - even if below max limits. Shielding one or part of portable panel would still be workable and prove this.
Hi @Boots in Action ,
Oops, my bad. Couldn't read 30A on one page and write it in a post without making a mistake. Agree, it is 30A maximum for the TPS1230. I have edited the that post to correct the mistake.
Still, something weird going on with these two panels. Need to do some faultfinding, and, I would suggest, the first step would be to put a blocking diode in series with each panel to eliminate this as the cause of the problem.
cheers
Mike
Oops, my bad. Couldn't read 30A on one page and write it in a post without making a mistake. Agree, it is 30A maximum for the TPS1230. I have edited the that post to correct the mistake.
Still, something weird going on with these two panels. Need to do some faultfinding, and, I would suggest, the first step would be to put a blocking diode in series with each panel to eliminate this as the cause of the problem.
cheers
Mike
@jazzeddie1234 , I am with you on all the above points. However, even if the controller did in fact cut charging rate to zero or nearly zero, voltage would still be shown on controller. Zero voltage is an indication of open circuit or short circuit in my opinion. Electrical potential is lost or going somewhere to a very low resistance. I am starting to put my money on the controller operation being faulty when presented with input current above single panel output. Been involved with lots of parallel connections with this controller and many others and never seen this problem before. Note that @Fallen has the output wired through the controller so he can see load out. This has been successfully tested and should have no effect on situation unless load exceeded rated 30A. What do you think?
Hi,
when you get a chance, can you get the measurements of Voc and Isc for the roof top panel when the sun is on it?. Without this, the figures above indicate the roof top panel is not contributing.
Interesting that your portable panel with one half side shaded gives half the output. This would seem to indicate that there might be blocking diodes in each of the sub panels.
Even more reason to have a look in the terminal blocks on the back of all the panels.
Sorry, but I love these sorts of problems.
cheers
Mike
I would try another controller firstly and confirm that the problem still existed. Saves soldering. Then if condition still exists and connections are correct at panel, then purchase diodes and fit for testing further. Cheers and keep up the good work. Also see my latest post to @jazzeddie1234 .
I didn't see the bit about the voltage falling to zero so I just assumed the current was zero and the TPS was refusing to charge the battery with both panels connected. So yes, a zero voltage suggests a faulty TPS given the 2 panels in parallel (and disconnected from the TPS) are showing reasonable voltage - even with one acting as a load to the other. But I agree with @mikerezny that the panels could be interacting all over the place with sun/ partial sun so a reuse of the bypass diodes as blocking diodes is a quick option - assuming they can be accessed (my ones are potted). Otherwise something like this would suffice for the test. https://www.jaycar.com.au/diode-mbr735-schottky-35v-7a-to-220-2/p/ZR1029
Hi Mike @mikerezny , just had another look at Voc and Isc for roof panel - well down on portable figures - 0.9A?? But seems to contribute more when connected in parallel with portable - combined Isc minus portable Isc leaves higher than individual Isc ( 13.5A - 11.8A = 2.05A). Could be that roof panel not in same sun position as portable?? Otherwise could we be looking at diodes in roof panel?? Just a thought!
To clarify, voltage didn't go zero when current went to zero. When I said "went to zero on both" i meant on both the screen of the TPS and on the meter. Sorry for the confusion! Voltage was the same.
Equally, the negative current on the panel may have been me having the leads the wrong way around. Will confirm next time the sun is out on the roof so I can get a more consistent set of numbers.
And yes, roof top was in partial shade in arvo so very low current compared to what it's provided before, and portable was in full arvo sun (with a bit of cloud).
Re diodes, pics attached! The info stated in the ads for these panels is typical cheap panel lingo: "foldable module is equipped with diode bypass technology, which helps to minimize power loss due to shade and guarantees reliable power supply in low light conditions".
Equally, the negative current on the panel may have been me having the leads the wrong way around. Will confirm next time the sun is out on the roof so I can get a more consistent set of numbers.
And yes, roof top was in partial shade in arvo so very low current compared to what it's provided before, and portable was in full arvo sun (with a bit of cloud).
Re diodes, pics attached! The info stated in the ads for these panels is typical cheap panel lingo: "foldable module is equipped with diode bypass technology, which helps to minimize power loss due to shade and guarantees reliable power supply in low light conditions".