Solar set up questions

vanski

'05 Box Snow Camper
You can get good panels from urban ore in Oakland on the cheap.. new, but left over from large commercial projects.

max (lol) your volts seeing as that CC can accept 100V. This is also very good with certain agms (lifeline as one example) and wet cells as you can raise the volts to desulfate them with that fancy cool Victron CC (look at the equalization charge functionality)
 

vanski

'05 Box Snow Camper
Thanks!

not sure ill start messing with custom charge parameters, that's well out of my knowledge range.
it’s just something to have in your back pocket as the batteries age. You can also do it with any good charger which allows you to specify the volts, but why buy that when you now have that capability with your Victron CC. Only problem is the Victron will only allow you to hit it with an equalization charge for 1 hour. Severely sulfated batteries, which is most likely what’s going on with your current batteries, require an 8 hour equalization charge. But anything helps.

**** note, and as stated above, not all battery chemistries will safely accept an equalization charge.
 

HarryN

Active member
Maybe try wiring the panels 2 series / 2 parallel with a new battery and see if things improve.

An 18 Voc or Vmp is pretty marginal to get any mppt controller to work correctly.
 
allllriighty

I was able to pull off each panel today and measure them independently, open circuit.

I was also able to get the specs of each panel. they are as follows.

pmax 80w (was told they are 100, so that's lame).

voc 21.5
vpmax 15.2-16.9 (unsure what this is)
Ipmax 3.83A-4.73A
Isc 4.97 amp

Build date: June 2001 (OLD AS FUCK).

ok, now for the circuit ratings I got when open testing them each individually.

EVERY SINGLE ONE came in the same.
18.85volts
0.4-0.485 Amps or 400milliamps. so insanely low/small

This was open tested, straight to the panel, not even the connections' hardware, just to make sure it wasnt the wires to the panel.

weird they are all identical. but it also makes sense to why my controller was reading 1.2 amps most of the time.

seems like my panels are old, fried, and beat up and can't product anymore.
 

autostaretx

Erratic Member
Actually, your testing description has a conflict in terms.
Measuring "current" cannot be done in an "open circuit" configuration.

Could you describe how you were getting that current (0.4 to 0.485 amps) reading?
i.e. Where were you attaching the wires to your meter?
What scale was the meter set on?

IF you have a typical volt/ohmmeter, it has a separate socket for a 10 amp current reading.
To activate that socket, the meter's selector knob has to be set to the 10 amp position.
The "10 amp" socket gets the positive panel wire, and the COM socket gets the negative.
That hookup should actually be testing the Isc of the panel, since the resistance between the 10 amp socket and the COM socket should be very very close to zero. (you can test that statement with another ohmmeter looking at only the "10 amp" meter (no panels attached).

I'm perfectly willing to believe that testing for Isc (as above) would only yield 0.4 amps for a variety of reasons, i'm just trying to clarify the situation.
(but among the issues: if EACH panel were capable of 0.4 amps, your "all four in parallel" should've yielded 1.6 amps (four times 0.4).)

--dick
 

Kevin.Hutch

2011 Mercedes 313 906
Just to clear up the point of "old" 25 years plus, is old even with the older technology, virtually all panels had a 25 year warranty even if they declared how much they degraded with age. However the warranty did not cover damage and it is unusual to damage 4 panels without some obvious cause.

As Dick correctly says, if the ISC (Short Circuit Current) is 0.4 amps (the panel spec says 4.97 amps) and 4 in parallel should yield 1.6 amps or 19.88 amps if up to spec.
 
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HarryN

Active member
Good news - no need to give any more thought to those old panels. Literally anything will be better. Scrap them out and move on.

Give them to the kids next door as a summer hobby. They put out so little power that it is unlikely that they can hurt themselves even if they don't use a charge controller on a car battery.

Your neighborhood status will go from solar newbie to solar expert in a week.
 
Actually, your testing description has a conflict in terms.
Measuring "current" cannot be done in an "open circuit" configuration.

Could you describe how you were getting that current (0.4 to 0.485 amps) reading?
i.e. Where were you attaching the wires to your meter?
What scale was the meter set on?

IF you have a typical volt/ohmmeter, it has a separate socket for a 10 amp current reading.
To activate that socket, the meter's selector knob has to be set to the 10 amp position.
The "10 amp" socket gets the positive panel wire, and the COM socket gets the negative.
That hookup should actually be testing the Isc of the panel, since the resistance between the 10 amp socket and the COM socket should be very very close to zero. (you can test that statement with another ohmmeter looking at only the "10 amp" meter (no panels attached).

I'm perfectly willing to believe that testing for Isc (as above) would only yield 0.4 amps for a variety of reasons, i'm just trying to clarify the situation.
(but among the issues: if EACH panel were capable of 0.4 amps, your "all four in parallel" should've yielded 1.6 amps (four times 0.4).)

--dick

I was putting the leads of the multimeter into the PV wiring. both through the connected wire, and by passing it and straight to the back of the panel to see if there was a difference.

I used a multimeter with the pen attachments, positive placed in the 10amp socket, and turned to 10amp setting. that is wehere i got my reading of 4.xxmA

according to my MPPT, i did once see 1.5x amp's at one point.


Just to clear up the point of "old" 25 years plus, is old even with the older technology, virtually all panels had a 25 year warranty even if they declared how much they degraded with age. However the warranty did not cover damage and it is unusual to damage 4 panels without some obvious cause.

As Dick correctly says, if the ISC (Short Circuit Current) is 0.4 amps (the panel spec says 4.97 amps) and 4 in parallel should yield 1.6 amps or 19.88 amps if up to spec.
yea, which leads me to believe they are old and toast.
 
Good news - no need to give any more thought to those old panels. Literally anything will be better. Scrap them out and move on.

Give them to the kids next door as a summer hobby. They put out so little power that it is unlikely that they can hurt themselves even if they don't use a charge controller on a car battery.

Your neighborhood status will go from solar newbie to solar expert in a week.

anyone have recommendations on panels?


would now be a smart move to use 24v panels and less of them? say 300w of 24v? or would that surpass my MPPT controller's capability?

can I even do that with a battery bank that is wired 12v in parallel
 
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borabora

Active member
Your controller is good for 100V from the panels and up to 30 amps into the battery. I wouldn't try to get too close to those values but a single 300 Watt panel should be no problem at all. 300 Watt panels are huge, so figure out where it would go first and how to mount it assuming you have a roof fan, possibly A/C and other stuff on your roof.
I'd go for the cheapest 300 Watt mono panel you can buy locally since shipping them cannot be very cheap. Your batteries will thank you -- assuming you were able to revive your batteries from the dead.
 

autostaretx

Erratic Member
In my case, i finally bought panels due to Home Depot offering 100 watt Grape Solar poly rigid panels for $89 each, with free shipping to my door. :thumbup: :thumbup:
They fit the limited space i had (i'd been looking for anything roughly 40" square), and i considered it a wash if i bought one 200 watt or two 100 watt (yes, about one possible row of cell area is "lost" due to the extra framing).
Separate panels will also let me play with the "series or parallel" question (if i so wish) in the future.
I opted for parallel (shade tolerance) for the moment.
I consider the $30 MPW controller a disposable toy/learning-experience if i decide to go MPPT.

--dick
 

HarryN

Active member
Solarland and grape are panels commonly found on RVs due to size.

Solarland tend to have more size options and pretty strong frames.

It might be worth making some plywood cut outs the size of a few panels and see if you are comfortable with getting them up on the roof without scratching up the van. A 300 watt panel can catch some breeze.
 
does the volts on the panel matter since I hhave 4 (12 volt) batteries?
i.e. 24v or 36v 300watt panel

Or am I required to have a 12volt panel?

from my very limited and new understanding, I should be ok with any of those three options, 12-24-36.

ya?

thanks in advance for helping me understand.
 

autostaretx

Erratic Member
does the volts on the panel matter since I hhave 4 (12 volt) batteries?
i.e. 24v or 36v 300watt panel

Or am I required to have a 12volt panel?

from my very limited and new understanding, I should be ok with any of those three options, 12-24-36.

ya?
Ya.

The MPPT controller will handle all of that. It can feed anything from 100 volts down to (about) 16 into 12 volt batteries
(its spec sheet will define the lowest voltage it can handle...)

--dick
 

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