Help with panel testing (Update with results)

[Bear in NM]

Please do not apologize, I really appreciate the in depth reply. I am still on the lower end of the knowledge curve here.

Yes, in the video I noted, she was testing mis-matched panels. And you have confirmed what she reported. I do not recollect much discussion here on series v. parallel in panels, unless the conversation of wire size and length was at topic. Hence my desire to test.

I had originally planned to add a second identical 135 glass panel, but decided that money spent might be better on something more portable. I could easily add a second 135 and hinge it to the first, but the weight would get a little high, and then I would have two glass panels to take four wheeling. The GZ panel folds up silly small, but was certainly silly money. A big premium on convenience. The folding 100 is so new that there is squat out there for reviews. I was actually pretty pleased to see almost 70 watts in my first run.

I am still confused when you note the integrated battery charger. Sorry for being daft, but is this a part of the solar charge controller that plugs into shore power? I looked at the Victron website and could not figure this out. I think a solar charge controller is a battery charger by definition? I acquired a decent Samlex battery charger (110v) last year, and it seems to be doing a good job. I am running duracell batteries that I cannot find the recommended charge profiles, but in monitoring the output when charging, it is cycling through a decent agm charge profile, starting at 15 volts. My new trailer is sporting a midnight solar MPPT, and does have programmable set point for charging through the panel. I have not fiddled with those yet, as I do not have a specific profile for my batteries.

I guess I need to look more closely at some of the calculators out there. Up to this point, I have not been trying to maximize, per se, but picking #12 for a remote panel, as it is more easily dealt with. PWM controllers as they were cheaper, and I did not have multiple panels. I was surprised at how small the 50 foot roll of #10 actually is, and weighs, as it just arrived yesterday.

Thanks for bearing with me,

Craig

 

[Bear in NM]

Dwh,

Sorry, cross posting as well.

This was the whole point of starting this thread, you guys seem to think (and all I have read to date ) series will be better, and this video I found indicated a test showing parallel was better for her mis- matched panels. Series should have the advantage of the smaller wire over distance, which is a bit of concern for me. I am clear the mis-matched panels will lower the efficiency, I was just trying to understand more.

Yes, I will load up the batteries, and fiddle around.

Craig

 

[john61ct]

I realize you're just doing this for fun, academic curiosity

but if you are at some point planning on putting your mismatched panels into production

then I want to advise, get a separate controller for each panel type

to the extent you want multiple panels per controller, they should match

 

[dwh]

I am still confused when you note the integrated battery charger. Sorry for being daft, but is this a part of the solar charge controller that plugs into shore power?

He's talking about DC-DC (battery to battery) chargers which also have integrated solar charge controllers.

Which would be something someone might have instead of an isolator or automatic connection relay (ACR).

 

[Bear in NM]

John,

Actually, not for just fun. My plan is to have both panels with me for some outings, and if I feel the conditions warrant, I would hook up both. I went back to you tube and searched for "mismatched solar panels", and all of the Alt-E store's videos came up. They have a whole series ( not parallel ) of these mismatch videos. I watched another where she confirmed that series was better for the particular mismatch tested. Unlike an earlier one, where parallel produced more watts.

She does start all of these videos with the same warning as you noted, best to have two controllers. And in one configuration, she demonstrated what DWH noted above, the lesser panel "drug" down the two panel array. I get the fact that if I want to optimize, I should run two controllers. But I still would like to know the best way to optimize with the single mppt controller in my trailer, and my current panels.

I do appreciate your input, as it is helping me learn,

Craig

 

[Bear in NM]

He's talking about DC-DC (battery to battery) chargers which also have integrated solar charge controllers.

Which would be something someone might have instead of an isolator or automatic connection relay (ACR).

DWH,

Thanks. I figured it was something like that. I have little understanding of them.

Craig

 

[Bear in NM]

Well, for you folks who were playing along, I have some results from testing today.

First, I have mc4 connectors and cables nailed down, as far as making. Only blew one connector in making wire pairs, but that was not enough coffee. Whether mc4 or anderson, or big battery cables, proper crimping tools sure save a lot of grief.

Second, I had envisioned that 50' or 25' runs of #10 solar wire would be unwieldy. Definitely not the case. I like the way the #12 landscape lays to a remote panel, but it will be nice to have the #10's as an option.

The sun was almost directly overhead, 75 degrees here in northern NM. I was testing a 135 watt glass panel, a new Goal Zero 100 foldable Nomad, with my Midnight Solar mppt controller, in front of two 80 ah Duracell batteries, in parallel. I had a light bulb plugged into an inverter, and had my 63 quart ARB fridge running full on. In all, I had 8 amps going out. I tried to quickly move through the different connections. The controller stayed in "Bulk MPPT" the entire time. The batteries were not drained much, to begin. I have a lot of raw numbers (watts, amps, volts from panel), but I will condense this down to just watts and amps. 25' of #10 solar wire.

Individual Numbers:
Glass 135: 90 watts 7.5A
GZ: 35 watts 2.8A

Parallel:
135 & GZ: 135 Watts 10.1A

Series:
GZ positive lead out: 90 watts 7.3A
135 positive lead out: 100 watts 7.6A

I decided to switch the positive lead out because the numbers were so pitiful.I would think that series is series, but not sure what to make of those results for using different lead out.

I then tested wire size and length, well, just because.

#12, 50', 135 panel: 95 watts 7.3A
#12, 50', GZ panel: 40 watts, 3.2A
#12, 50', parallel: 121 watts, 9.5A
#10, 50', parallel: 120 watts, 9.2A

The #10 tested above at 25': 135 watts, 10.1A

My newbee thoughts from this limited test. Looks like series really sucks with these mismatched panels. I took a small hit in amps when running parallel, but the watts went up, over individual numbers. Maybe the need for two controllers is not terribly great? I was kinda freaking out over the low output from the GZ panel, but I tested again later when the sun was a little higher, and it increased power, a small percentage increase over the retested glass panel. Maybe the GZ prefers better angle control? I also saw 60 watts last weekend with the GZ at a similar time of day, on a different battery bank, and immediately hooked it up to this same bank, and saw closer to 50 watts. Pretty sure the battery soc has a lot to do with my numbers. And certainly I need to test for real. But it looks like a pretty decent penalty for foldable convenience. And I probably should have tested with more like 12 amps going out to the load.

I definitely need to carry my #10 wires with me, and use shorter wires when possible ( I know, duh!). When I return from my next trip, I want to retest series with a depleted battery bank, but I cannot believe that the results could change, that much. For now, with my limited 12v use when camping as I do, I will probably just run the big glass, and keep the GZ for changing bad conditions. I can easily throw the GZ on top of my trailer or truck, for camp spots where I might not want to scream "solar panels for free taking".

anywho, that was fun and fwiw,

Craig

 

[dwh]

Huh. I would have thought The Kid would do better with series than parallel. Guess not.

Kinda strange that the individual panels put out more watts with 50' of #12 than they did without it.

 

[Bear in NM]

Well, I did not have a clue what to expect. And I am not sure this first round of testing was fouled by the soc of the pretty full bank. Or a stray butterfly that I missed.

I did test the series twice, so pretty sure I did not fat finger something. Still just a point in time, static test, for the most part. I will certainly do more. And if I cannot get better performance from the GZ panel, I am gonna strip the leads, and plug each bare wire into into each my ears. On a sunny day, of course.......

Craig