Two solar panels

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Caladh

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….parallelled in to one Victron 15/75amp smart regulator. I don't seem to see as many amps going into the battery as I think I should on a sunny day. One 80w flexible panel outputs 22v the other 80w solid 19-20v. I know the regulator will regulate to the lowest. However I’m only seeing 3-4amps which isn’t much better than with one panel. Question - is there Victron regulator that has 2 inputs and will regulate separately?
 
Caladh said:
….parallelled in to one Victron 15/75amp smart regulator. I don't seem to see as many amps going into the battery as I think I should on a sunny day. One 80w flexible panel outputs 22v the other 80w solid 19-20v. I know the regulator will regulate to the lowest. However I’m only seeing 3-4amps which isn’t much better than with one panel. Question - is there Victron regulator that has 2 inputs and will regulate separately?
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No.
 
Caladh said:
….parallelled in to one Victron 15/75amp smart regulator. I don't seem to see as many amps going into the battery as I think I should on a sunny day. One 80w flexible panel outputs 22v the other 80w solid 19-20v. I know the regulator will regulate to the lowest. However I’m only seeing 3-4amps which isn’t much better than with one panel. Question - is there Victron regulator that has 2 inputs and will regulate separately?
Click to expand...
It is mid October and my latitude is 50°N, perhaps you are expecting to much.

What is your usage?
 
You would be better with two solar controllers especially given the different voltages, but it sounds like one panel or the wiring etc may be defective.

I would test each panel separately before you make any changes.
 
Do they have similar voltage characteristics or you could be restricted to the lower voltage one? Similarly to if you put 2 panels in series and they had different max current.
 
Caladh said:
With one panel I’m getting around 3 amps with 2 panels connected around 3.5-3.8 amp - so you think that’s ok Paul?
Therefore with my thinking is with another controller I’d be seeing something like 6 amps combined?
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Check each one separately. But, you may not get the combined current when you connect together, because the batteries may not be able to accept that amount of current.

In short, check each panel separately and then connect together. If you don't get the combined current, try turning as much equipment on as you can see if the current increases.

Also, where/how are you measuring the current?
 
PaulRainbow said:
Check each one separately. But, you may not get the combined current when you connect together, because the batteries may not be able to accept that amount of current.

In short, check each panel separately and then connect together. If you don't get the combined current, try turning as much equipment on as you can see if the current increases.

Also, where/how are you measuring the current?
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Seeing current on my Victron battery monitor. I’ll certainly try each one separately again as you suggest. I tested the solar output voltage at the cables prior to connecting to the controller so I fail to see that either of the panels is faulty. In the end would it be better to have 2 controllers? Thanks Paul for your help here.
 
Caladh said:
However I’m only seeing 3-4amps which isn’t much better than with one panel
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Caladh said:
Seeing current on my Victron battery monitor.
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Looks like you are looking at reg output current. The reg will only supply what the battery needs and can accept.
If you want to check your panels output current, use a separate amp meter on the panels input to the regulator.
 
Caladh said:
Seeing current on my Victron battery monitor. I’ll certainly try each one separately again as you suggest. I tested the solar output voltage at the cables prior to connecting to the controller so I fail to see that either of the panels is faulty. In the end would it be better to have 2 controllers? Thanks Paul for your help here.
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Set each panel squarely facing the sun and disconnected from the controller. Measure both the open circuit volts and the short circuit current.
Compare the readings with the specification for your panels after allowing for the extended path of the sunlight through the atmosphere due to the low height of the sun at this time of year.
 
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Am no expert and probably missing something, but wondering why no-one's mentioned changing to series connection.

I understand the regulator can take the voltage (up to 75V).
 
VicS said:
Set each panel surely facing the sun and disconnected from the controller. Measure both the open circuit volts and the short circuit current.
Compare the readings with the specification for your panels after allowing for the extended path of the sunlight through the atmosphere due to the low height of the sun at this time year.
Click to expand...

(y) This is the best method to test each panel.

Caladh said:
In the end would it be better to have 2 controllers?
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Two controllers will produce a higher total energy yield. The improvement would be worthwhile, but not enough to account for the very low output you are experiencing from the second panel, so I think something else is wrong. Testing the short circuit voltage is not a foolproof method of checking a panel.
 
Caladh said:
Seeing current on my Victron battery monitor.
Click to expand...
I doubt you will get any meaningful readings unless you are sure, or make sure, that the battery is sufficiently discharged in order to accept the current expected from the two panels. Do you know the approximate SOC?
 
To eliminate the effect of solar regulation distorting the results briefly add a load equal to or greater than the potential solar panel output (160w in this case) whenever taking readings from the system.

This will eliminate a high battery SOC or controller regulation from producing misleading results. There is no need to drain the batteries if the load is greater than the input.
 
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Caladh said:
Thanks for all this valuable info which I’ll endeavour to take forward to the boat in a couple of weeks. Finally how do I measure the short circuit current of the panels as requested above ?
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Treat yourself!!! ?
XnPMrR1.png


Then you can just connect a piece of wire to short between the Pos & Neg terminals and clamp the meter over than, see what they put out.
DC clamp meter is a great toy to buy for the boat ?
 
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