Mixed Panels Madness

[WheelingOn]

Originally Posted by John Hilley

Why not just use a Trik-L-Start, that way the chassis battery will get charged on solar and shore power.

Agreed. There are simpler solutions for this (off topic) goal, than creating a separate controlled solar array.

[vsheetz]

Fusing each panel in a parallel setup is not needed if just one panel in the string. Just provide circuit protection after the combiner point / before the controller. If two or more panels in a string, and multiple strings, then circuit protection should be provided for each string.

For example. I have three strings with five panels in each string. Each string is wired to a combiner box with a DC circuit breaker for each string.

A note on the battery side of the controller, it should have circuit protection near the battery bank. And there should be a note advising servicing personnel there is another source tied to the battery bank.

[baphenatem]

Originally Posted by Canyonlands

Great article indeed. It doesn't list any of the panels in question but details a more suitable way to rate PV module performance.

Since someone called the Grape Solar 180W module performance in question, I'd also like to see the source tests for this position. I have both the GS 160 and GS 180 panels standing side-by-side here in my home and they are not identical in appearance, front or back.

Data labels on the back of these list the following:

GS 160W: 8.88 IMPP 18.0 VMPP
GS 180W: 9.15 IMPP 19.67 VMPP

Our factory installed 100W Zamp module is imprinted ZS-100P and further data isn't visible to me as the panel is mounted with less than an inch of standoff. Online information is scarce for Zamp's panels as well. I've only found data for one poorly identified Zamp 100. Below are those numbers:

ZS-100P: 6.1 IMPP 19.1 VMPP

If I understand correctly, given those values, these panels would be better matched in a series array. We're not interested in doing so. We're working with limited roof space and will only have one controller and array.

I see few speaking of over current protection for individual panels. I didn't find much talk of this online. If it's an inline fuse between the module and combiner we're talking about, is this a standard? Fused on the positive side of each module?
I believe there is a self-resetting fuse between the combiner box and controller but I haven't seen it with my own eyes.

Thanks for the excellent feedback.

I suppose that I was the one in another thread that asked the question about the Grape Solar 180W modules as the price vs output rating ratio was bit off, but it sounds like the figures are legit, given a couple of early reports.

Yes, you do want to connect those modules in parallel, and no, you don't want to put them in series since you'd then limit the whole string to the amperage of the lowest rated one. Not to mention, the controller that you have now is only rated for 25V max (if I recall).

The overcurrent protection for each module (or string of modules) is a Code requirement whenever there are more than two modules or sets of modules connected in parallel. There are a limited number of exceptions to this, but it is essentially to keep backfeed currents from burning up a module that has an internal fault, thus potentially catching it on fire. In your case it is especially important because of the disparate wattage ratings of the modules. In essence, the 100W module will have smaller internal conductors and will (usually) be more susceptible to damage from the other two modules should it fail internally.

Don't fret that the Vmpp voltages aren't a perfect match. You won't really notice the difference. There will be bit of a reduction in the overall system output, but as has been pointed out the numbers are somewhat fictitious to start with.

[WheelingOn]

Thanks Tom.

Yes, 25V is the listed max input array limit for the Zamp 30A controller.

[Reed Cundiff]

Concerning dissimilar panels: we have a 315 W and a 100 W panel on our Roadtrek. Son designed and fabricated to utilize two controllers to 12 V nominal LFP battery bank. Timon alluded to this.

We have gotten close to maximum output from panels at 10,000' in the Rockies in June and July with 90 V from panels to controller on fifth wheel. Nowhere near this at beach in Yucatan in winter with 12 V from panels to controllers.

Reed and Elaine

[WheelingOn]

Originally Posted by Reed Cundiff

Concerning dissimilar panels: we have a 315 W and a 100 W panel on our Roadtrek. Son designed and fabricated to utilize two controllers to 12 V nominal LFP battery bank. Timon alluded to this.

We have gotten close to maximum output from panels at 10,000' in the Rockies in June and July with 90 V from panels to controller on fifth wheel. Nowhere near this at beach in Yucatan in winter with 12 V from panels to controllers.

Reed and Elaine

Thanks for the data point and feedback Reed. Kelly and I met you two over 2 years ago at Klahowya (Coastal WA). We'll be going full time in a couple of years. Hope to see you out there again someday.

We won't be running two controllers in this coach. It happens I've just ordered another charge controller. I didn't like the 25V limit on the Zamp controller so I ordered a Victron BlueSolar 100/30. It cuts off at 440 watts, which happens to be what my 3 PV modules amount to. We'll see how well it plays with the 100 and 160/180s. Also picked up the Victron BT dongle as to monitor and adjust the controller from my phone.

Now the mystery will be polarity. Zamp's panels and panel wiring are reverse of everyone else. That means the combiner to controller wiring is reversed too, right?

[Timon]

Originally Posted by CountryFit

yes you can. for parallel connection, what matters most is that the panels output the same or very close voltages. those with higher wattage will produce higher current, but that is ok as they are parallel.

similarly, for series connection, you'd check to make sure they have same or similar current rating. the higher watt panels will have higher voltage, that will add to the total voltage of the string, no hinder for the performance of other panels on the same string.

While technically correct in practice it's not always that easy to find panels which will match the voltage or current when mixing. Better to stay with the same matching panels.

it's interesting to read your numbers... 160w out of nominal 180w in "real world"? mind asking do you really have such a system running on your mh (if you have one) and you saw the numbers, or you read out somewhere from someone?

I know because they publish their STC and PTC ratings. STC are what's called "Standard Test conditions" and PTC, aka PVUSA, are the real world ratings. In this case the STC=180W and the PTC=160W.

The reason you don't see PTC ratings on AMSolar and Everygreen panels is that they don't send them to the PVUSA testing center in Davis, California which is the way you get your panels certified.

There is a official published table which lists every manufacture of panels that have been tested. BTW, You'd be surprised how large the differences are in PTC ratings on panels that have the same STC ratings. This is the table that's used when you apply for solar credits.

[baphenatem]

Originally Posted by Canyonlands

Thanks for the data point and feedback Reed. Kelly and I met you two over 2 years ago at Klahowya (Coastal WA). We'll be going full time in a couple of years. Hope to see you out there again someday.

We won't be running two controllers in this coach. It happens I've just ordered another charge controller. I didn't like the 25V limit on the Zamp controller so I ordered a Victron BlueSolar 100/30. It cuts off at 440 watts, which happens to be what my 3 PV modules amount to. We'll see how well it plays with the 100 and 160/180s. Also picked up the Victron BT dongle as to monitor and adjust the controller from my phone.

Now the mystery will be polarity. Zamp's panels and panel wiring are reverse of everyone else. That means the combiner to controller wiring is reversed too, right?

Just check the polarity with a meter to be sure. I haven't worked with any of Zamp's stuff so I'm not exactly sure what you are referring to. As a rule red is positive and black is negative, even though the 12V systems on RV's use a different color code.

You'll like that Victron charge controller, especially with the Bluetooth dongle. The only drawback to them is the lack of a remote temperature sensor, which means that you'll want to install the controller in an area that has the same ambient temperature as your batteries. The unit takes a temperature snapshot when it starts up and that is how it determines how much compensation to apply to the output voltage. By the way, don't trust the auto voltage sensing feature on them. I have one that i use on both a 24V lawnmower and my 12V motorcycle batteries and it never makes the automatic changeover. I have to go in and manually set it every time I switch.

[Reed Cundiff]

Canyonlands - we remember you two from Klahoywa (sic). I believe you had bikes or trikes. Klahoywa was delightful but not the greatest place for solar; however, we were still collecting around 750 W-hrs a day there. Olympic Pensinsula is just not the best place for solar. We called the National Park Service CG at Mora and asked about a spot with solar. The gal said "Sir, this is a rain forest, solar panels are not terrible effective!"

The reason for the mismatched voltages on our Roadtrek is that there is very little real estate. A 315 W (35 V or so) fits over the rear deck behind the Fantastic Fan and a 100 W (12 V) fits in front.

As others have noted, going to higher voltages does decrease requirement for large diameter cabling and for massive controllers. Our nominal 1400 W array on 5the wheel would be 116 amps at 12 V and is only 17 amps at 90 V. The battery suite is 48 V nominal or 30 amps to battery suite.
Reed and Elaine

[WheelingOn]

The Olympic Peninsula is fine for solar...if you stay out of the trees, and over in view of Mount Baker. You two had the bikes BTW; Kelly and I were on foot.

Back on point, I couldn't fully commit to the Victron. No remote temp sensing isn't a big deal for some, but the View/Navion batteries aren't fully enclosed from the outside elements.

I changed my order to the Blue Sky 3000i. The form factor is nearly a straight swap for the outgoing fairly well-featured Zamp PWM controller.

This little upgrade will make a noticeable difference in the View. 340W of additional solar, from PWM to MPPT and two Lifeline 6V AGMs to replace the factory Group 24s.

If the Zamp panel doesn't play well with the Blue Sky controller, I'll just remove the 100W panel. It will be interesting to see how it goes.

[baphenatem]

I got to playing around a bit in the solar lab at work today while commissioning some new charge controllers and meter shunts, and paired up an older Astro Power 100 Watt module with a new HQST-100D. The AP was putting out 78W and the HQST 83. The max power voltage ratings on the two are about 2.5 Volts different. The net result: 156W when paralleled, a hit of only 6 Watts.

[CountryFit]

Originally Posted by baphenatem

I got to playing around a bit in the solar lab at work today while commissioning some new charge controllers and meter shunts, and paired up an older Astro Power 100 Watt module with a new HQST-100D. The AP was putting out 78W and the HQST 83. The max power voltage ratings on the two are about 2.5 Volts different. The net result: 156W when paralleled, a hit of only 6 Watts.

good to know. obviously not bad.

[cruzbill]

Tom's citing code requirements for string fusing is important. Before I retired, I operated a large solar array (over 5,000 120w solar panels) and we started having a problem with some of the panels. A circuit trace would overheat, and on some panels caused the panel junction box to catch fire; the panel glazing would then shatter.

Curiously, the string fuses would not blow (8a, if I recall).

The panels, made by BP, I notice now have been recalled and BP has long left the solar market.