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

[DMH]

Sorted! I had a few hours on my hands over this weekend and was moving wires and tapping connections here and there this morning when @Mike90250 posted a couple of questions and one of them was about the Voc of the panels. Of course!!! If I orientate the panels with no load the voltage will rise according to the amount of sun exposure, so I wired the panel to the volt meter and then moved the panel, when the Voc was at it's highest I switched in the load i.e the Victron and it worked great! A couple of minor connection changes to the wiring, plug the panel in, find the sun switch on and done. I have tested a few times and it works perfect, just uncouple the load and move the panel, I get to see what the additional amperage is to the existing ammeter and of course it replicates that coming from the Victron, but I can at least confirm that the Victron is getting all it needs to do the job, I will have to order a meter with a higher voltage capability, as I had only ever read actual battery voltage so the meter was rated for maximum 30 volts, if I do something stupid like switch on both panels with no load I risk 40+ volts reaching the 30 volt meter.

Many thanks for those who have offered their thoughts and of course @Mike90250 gets the silver star!

Off to order a meter.

regards

Dave

[littleharbor]

Best of luck. Glad we were able to help
Mike

[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

[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]

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

[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]

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

[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.

[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)

[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]

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]

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

[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

[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]

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