I want to know what my SP are supplying in terms of amps.

[DMH]

I asked this question on another forum but that was a generic electricians forum and I think either I was asking the wrong question or what I actually needed was misunderstood, I was given a possible solution but it meant having the two panels in series, something I cannot do, so hoping to get the another answer here.

What I have thus far in my 4 x4 is:

2 X BP solar panels, one is on a slide under the roof rack, the other on a long cable to enable
1 X Victron 75/15 charge controller as recommended by a SPF member and it works fine thank you. Since the original install a couple of years ago the addition of the Victron has enabled the batteries to charge a little quicker which is great.

I have the supply from each SP going to switches which in turn goes through an ammeter to the Victron, the charge output cable to the batteries also has an ammeter in the line.

I was hoping to see which SP was producing X amps, and also use the meters to work out the best orientation to the sun of the roaming panel for maximum amps.

The problem I have is I am seeing identical readings from the input ammeter to the output meter regardless of battery state. I was given an explanation but it did not actually relate directly to the issue or at least did not appear to, I guess I am just not articulate enough?

Can someone provide a diagram or am I asking to move the moon as it is not actually possible to do what I want? FWIW I use analogue gauges, LCD screen go black in direct sunlight and LED are unreadable.

Am I clear with this requirement/question.

TIA

regards

Dave

[littleharbor]

How about a DC clamp meter? While you won't have a fixed gauge you can easily get current readings from either panel. Actually a simple multimeter will work as long as the current is less than 10 amps

[DMH]

How about a DC clamp meter? While you won't have a fixed gauge you can easily get current readings from either panel. Actually a simple multimeter will work as long as the current is less than 10 amps

Well herein is the problem, I can read the amperage from the panel as I use an inline fixed meter and the same is indicated by a clamp over the cable meter however, what I don't understand is the indication from the input from the solar panel is the same as the output from the Victron, in other words it seems the Victron only uses what it needs from the solar panel.

Thanks for the thought though, keep them coming.

Dave

[littleharbor]

In bulk charging all available current should be being accepted by the batteries. As the batteries near being full they will accept only what they can. If you have other loads present then all available current can be passing., otherwise the panel output will throttle back. My tri-metric shows what current is going into the batteries but my Midnite classic shows ALL current being produced. the difference is going to whatever loads are drawing current at the time.

[DMH]

In bulk charging all available current should be being accepted by the batteries. As the batteries near being full they will accept only what they can. If you have other loads present then all available current can be passing., otherwise the panel output will throttle back. My tri-metric shows what current is going into the batteries but my Midnite classic shows ALL current being produced. the difference is going to whatever loads are drawing current at the time.

Hi and thanks for that, I did check out the Midnight Classic and see it is aimed more at a full house installation and is way too expensive for a simple 4X4 install. I fully understand the battery not accepting charge once it/they are full, I did run the batteries down a little and then put the panel in full sunlight and the Victron goes into bulk, the input from the solar panel showed four amps and the output from the Victron is the same, I gave it about an hour and the Victron went to absorb and then started to throttle back and went to float. During these stages despite the panel being moved to track the sun the measured output from the inline ammeter in the supply from the panel stayed fully inline with the Victron output. There are zero other loads, fridge unplugged (my main reason for the solar) and I even turned off the interior lighting. Any and all parasitic loads have been removed, clock and radio disconnected, and as it is IMO a 'proper' off road vehicle with no computers/ECU's etc, so nothing else to draw power which allows me to offer the forum exact figures to help work this problem out. I say 'problem' but this is only me being pedantic, the system works perfect, but I want to monitor panel output to ensure I am getting the best from the panel position.

Consider this, I can see the Victron is charging the batteries at say three amps, and the solar panel output is showing three amps as it mimics the Victron output, I have no idea if I should move the panel/s, the batteries could well take an extra amp and moving the panels might give me that amp? Of course if the batteries are near full and the Victron is showing an output of say two amps but the panels are showing an output of four amps I know there is no need to move the panels, the amount of amperage available to the Victron is sufficient for its needs.

I hope I am explaining myself clearly, I want to know that each panel is offering it's best and that I am giving the Victron as much amperage that it needs to do its job. It is possible that the Victron prevents the panels from allowing excess amperage through, a 'road block' if you like? This would at least explain why the panel readings mimic the Victron output. Another thought re the Midnight Classic, if the unit is big enough to bolt to a wall it may have an internal shunt (with heat sink/fan) so allows excessive or unneeded amperage to go to earth?

I appreciate your input and would welcome more.

regards

Dave

[DMH]

I am having a little grief with the forum settings, in an effort to reply with as many facts as possible, unfortunately the forum times me out, and then then next thing that happens is my post gets listed as spam. So this means it is not seen by other members thus forcing a time lag in getting replies, so I apologise if this appears to be me being a little tardy, I am in fact up at 04.00 in the morning typing up a reply.

regards

Dave

[Mike90250]

OK, what you are seeing is the controller throttling back as the battery approaches full charge. Orienting panels won't improve things if the controller is already cutting back on the charge.

If you find yourself finishing the day, still not fully recharged, you should bump up the Bulk voltage half a volt, and the higher voltage will charge the battery a little faster, getting more watt hours into the battery at the end of the day.

A simple soda straw & plastic lid taped to the outer corner of a PV panel, is a easy sun gauge, point the panel (and thus the straw) at the sun, and adjust the angle so the straw makes the smallest possible shadow on the lid it's stuck through. (gotta make sure the straw is not crooked in the lid hole)
As the sun moves, it's about 30 minutes before there is enough change to bother adjusting the panels again.

[DMH]

Hi and thanks for your input and the straw idea. I have no problems whatsoever with the batteries reaching full charge, the overall system works great. Are you saying I have no way of monitoring shall we say available amperage from the two panels using the Victron controller?

I had thought about using volt meters instead of ammeters, simply moving the panels to the highest voltage reading may be the answer, I will need to see if the voltage is suppressed by the controller as well though?

regards

Dave

[Mike90250]

To go further,
Whats the Voc of the panels ?
Wired series or parallel ?
Is the controller PWM or MPPT ?

PWM controllers work with amps input = amps output
MPPT controllers work with watts input = watts output

Temperature controls the raw output voltage of PV panels (colder = higher output voltage),
solar brightness controls the amps (brighter = higher amps)

[Ampster]

.....
I had thought about using volt meters instead of ammeters, simply moving the panels to the highest voltage reading may be the answer, I will need to see if the voltage is suppressed by the controller as well though?

What is your purpose? Do you want to see the maximum power your panels can produce or do you want to see the maximum current they produce before going into the controller?
I am assuming the usual definition of Power equals Amps times Voltage.

[DMH]

To go further,
Whats the Voc of the panels ?
Wired series or parallel ?
Is the controller PWM or MPPT ?

PWM controllers work with amps input = amps output
MPPT controllers work with watts input = watts output

Temperature controls the raw output voltage of PV panels (colder = higher output voltage),
solar brightness controls the amps (brighter = higher amps)

21.40 Voc
I sometimes go out with just the car which has one panel, if staying for a few days I go with the roof rack which has the second, so parallel it is.
Victron 75/15 MMPT

Car is outside and presently doing some testing, so if you think of something let me know please.

Regards

Dave

[DMH]

[QUOTE=Ampster;n407925]

.....
I had thought about using volt meters instead of ammeters, simply moving the panels to the highest voltage reading may be the answer, I will need to see if the voltage is suppressed by the controller as well though?
/QUOTE]

What is your purpose? Do you want to see the maximum power your panels can produce or do you want to see the maximum current they produce before going into the controller?
I am assuming the usual definition of Power equals Amps times Voltage.

I am a little shall we say 'data hungry', I like to know what is happening and why. I want to see how much current is going to the controller from each panel. And a plus would be if I could look at a meter be it amp or volt move one of the panels keeping alignment with the sun and know I am giving the controller as much sun as possible.

Many thanks.

regards

Dave

[DMH]

If anyone has a clue how to achieve what I want please reply asap I am with the car all day today and tomorrow with both panels available, so I can test thoughts/ideas. I have at my disposal the usual, ammeters, volt meters, DMM, clamp on meter, blah blah blah.

TIA

regards

Dave

[littleharbor]

Your Victron 75/15 controller is an MPPT controller, (right), ? Being as such you need to series wire your two panels. When you separate the two panels you are creating a situation that the controller isn't meant for with lower than optimum voltage.

[DMH]

Your Victron 75/15 controller is an MPPT controller, (right), ? Being as such you need to series wire your two panels. When you separate the two panels you are creating a situation that the controller isn't meant for with lower than optimum voltage.

You may have read earlier that is not an option, the Victron works fine with one panel or two, as long as you do not exceed the max voltage/amperage.

But thanks for the thought. I think I have it sussed.

regards

Dave