issue w/Victron Energy SmartSolar MPPT 75V 15 amp

photo2000a

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hi. i am new to solar and. hit a wrinkle that i hope is something simple/obvious i might have overlooked.

Using 2 solar panels 12v. i measured the output of ea. and was getting about 15v. I hooked them up in series and measured 30v. thought i was good.

plugged it into my Victron Energy SmartSolar MPPT 75V 15 amp controller, and measured across. the terminals and got about 12.5v. the bluetooth app showed same.

so i unplugged the solar panel measured across it again. 30v. so it seems once i plug it into the controller the pv terminals show 12.5. I measured the battery. and load terminals. got about 12v using it w/a 12v battery which for testing i did. disconnect and i had no load connected just a volt meter.

any ideas. why the controller isn't sending power to charge the battery w/30v from the solar. should be enough to activate the charge ckt, but. dunno why. i am not measuring 30v at the pv terminals when i plug it in

anyone have any ideas what i did wrong?

thanks
 

Bob B

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When you measure the voltage of the panels while not connected to anything, you are measuring the open circuit voltage of the panels. Once you put a load on them that is going to change.
You may need to test the panels individually with a load ... independent of your current wiring. You could have a bad connection somewhere, or a bunch of other possibilities .... A divide a conquer approach is needed.

What kind of current are you getting?
 

mikefitz

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The battery needs to be connected to the controller before the the panels are connected.
Its not clear what type of panel you are using, normally there will be a specification label on the back of the panel indicating the voltage and current.
15 volts from a panel in sunlight sounds low, do you have a link to the panels, a picture, or a description, ( size of panel and number of cells).

Mike
 

photo2000a

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Hi appreciate the replies, Bob B, I did measure them individually I got the readings mentioned above, the current wasn't mentioned since i have no load on the unit and the voltage so far 12.5 doesn't activate the charge ckt. my goal was to use it to just charge the battery

Mike, I did in fact have the battery connected first. the panel is https://www.amazon.com/dp/B07C34GHGV?psc=1&ref=ppx_yo2_dt_b_product_details. I suspect the voltage was low as it has been a bit overcast.

Guess i am not sure what i should try next or if there is a way to reset the controller maybe that might help? Thou I can't figure why it drops like that...
 

frthompson

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You may want to test it when connected to a battery that you know is below a full state of charge. Also, I don't know the details of that charge controller, but my Victron has to be set for the correct battery type or the charge parameters correctly programed.
 

chrisski

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Plz check the SCC to determine if the battery is set for 12 volt or 24 volt.

One panel alone or two in parallel does not reach the. minimum charging voltage to allow the SCC to charge. MPPTs like to see about 5 volts above battery voltage to charge and this panel is only 15 volts. Two in series may not reach the minimum for a 24 volt battery.

Could also be wires too long and skinny and excessive voltage loss. I killed a battery because I extended cables on a tiny solar panel with small gauge wires by 25’ because of excessive voltage loss.

I am interested though because I have a 75/15 waiting for install on for a 24 volt 25 ah battery I’m building.
 

photo2000a

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hi. it is set to 12v. to match my battery. so i figured w/2 panels outputting. 30v it should be more then enough. the wires are actually pretty heavy ga and maybe 8ft. very good. idea. but either way. if i have 30v on my solar terminals and plug it into the. controller it should. stay around 30ish. not drop to 12.5. since it working it's obv not a dead short in the controller. i can't say if the controller is. defective. or if there is a reset for it i can do maybe i over looked something obv .
 

chrisski

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Can you include pictures of your set up?

I won’t have my 75/15 installed until next weekend. I do have a 100/50 and 100/30 and I can’t think of anything else to check.
 

photo2000a

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hi. i apologize. i don't have a way to take a meaning full photo at this time. perhaps after i get this problem fixed, and i mount everything up i could certainly do a follow up shot.
 

Bob B

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One thing you have missed is the importance of checking current (amps) as well as open circuit voltage. Your open circuit voltage seems to be OK, but we don't know about your current.
Here is a video that shows how to test that .... you could test the panels individually, but that won't be necessary unless you don't have the proper current.
If the panels are connected in series, your open circuit voltage should be twice what each panel is rated for .... the short circuit current should be at the rating for 1 panel.

 

mikefitz

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Are the panels new or used. Flexible solar panels have a high failure rate.

On testing each panel disconnected from the controller with a volt meter meter and some strong daylight/sun on the panel, expect just over 20 volts. If you are confident in measuring current, with the meter set to the 10A range and connect to the output of the panel, you should see around 2 amps in sunlight, less if its cloudy but still a measurable current.

If you do not get these readings either the panel or the connectios to it are faulty.

With the low voltage readings you have already taken ( 15 volts per panel), my best guess is that the panels have partially failed. This type of failure on flexible panels is very common.

Mike
 

photo2000a

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Hi Mike. thanks, since i. was in a overcast day I thought 15v was ok, i'll have to test that better on a strong sun day... i'll also try to test each panel to see the current hopefully i didn't get 2 bad ones. Thanks for the video Bob . I'll have to test it tomorrow am. greatful for the tips!
 

mikefitz

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The panel open circuit voltage should be near the specified value, over 20 volts, for most daytime conditions, unless its really dull.
If possible check the meter against a known voltage like a car battery, if the meter Internal battery is low you get strang readings.

Mike
 

photo2000a

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I thought my panels value should be 17v but wasn't sure how sensitive it should be on a overcast day. wasn't. dull just not. clear sun, kinda new to this, my meter. is calibrated so meter for sure is. good. in the am. i'll make some current checks. etc. hopefully. it's something simple appreciate. very much. the help Mike
 

photo2000a

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hi made the test, not sure how safe that video is was always told not to measure current directly accross the pos/neg terminals as in the video but tried anyways here are my results, good sun both panels 20v. both current .040. couldn't tell the scale . i bout the first panel just long enough to not be able to return it, the 2nd panel last week both from amazon 2 diff. vendors, not sure the odds of getting 2 exactly the same bad/same problem? they def look perfect. today is sunny. is there anything else i could check or am i sol?
 

chrisski

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both current .040. couldn't tell the scale .
Measuring current can be difficult. The internal fuse can blow pretty easy. I recommend taking the fuse out and ohming it to see if its burnt out.

My first multimeter was rated for 10 amps of current, but when I measured 2.5 amps, the fuse would blow before I would get a reading. A second different multimeter worked just fine.

So, before condeming the panel, I recommend checking the fuse and also getting a measurement of something. Even if you take a AA battery and a resistor.

That will just give you confidence the meter is working and the panel is bad.

For a reference, on my working 18 - 22 volt 100 watt panels, I get between 1 and 6 amps depending on how much sun its getting. Less amps when cloudy or in the morning and the most amps sunny and at noon.
 

Bud Martin

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hi made the test, not sure how safe that video is was always told not to measure current directly accross the pos/neg terminals as in the video but tried anyways here are my results, good sun both panels 20v. both current .040. couldn't tell the scale . i bout the first panel just long enough to not be able to return it, the 2nd panel last week both from amazon 2 diff. vendors, not sure the odds of getting 2 exactly the same bad/same problem? they def look perfect. today is sunny. is there anything else i could check or am i sol?
Can we see your meter?
Did you verify if the DCA function of the meter is OK by performing shorted circuit current test on AA or AAA battery?
 
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photo2000a

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ok that is a good idea, i ordered a shunt and a incandescent light bulb just to experiment , fuse was ok, so i didn't blow it, but might not have measure correctly w/this particular meter prob. have it. soon. again. grateful for the tips. i kinda thought this would be a little more straight forward. but def some vodoo going on. once i can flesh out if it's the panels or controller. all should be good.
 

photo2000a

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hi Bud, sure. am attaching a photo of my meter , not the best but it is calibrated. this was taken while hooked directly to one of the panels full sun. 20v
 

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Bud Martin

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That is good meter, I have 189 model. I would perform the shorted battery test to make it is working just to be sure.
 
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