I currently have six 100 watt 12v Renogy Mono panels with the specs below: note 36 cells per panel.
I am looking at buying some 12v Rich Mono panels with the specs below: note 33 cells per panel.
I currently use a pair of Bogart PWM charge controllers.
I want to add more panels and upgrade to a Victron MPPT system and also want the flexibility of connecting the panels in various series-parallel configurations.
The Rich panels are the only panels I can find that match the existing Renogy volts and AH, and my physical size requirements. Moreover, the Rich panels are the only panels I have found that have 12 AWG wires rather than 14 AWG wires. My old Renogy panels have 10 AWG wires.
Question: Will the 33 cell Rich panels pose a problem?
PS: I still do not know if the Rich panels have any diodes. My research is ongoing.
Thank you for any input you can provide!
For MPPT controller, if you are placing panels in series so the Vmp is moderately above battery voltage there is no problem.
Do not use a 32 or 33 cell panel, single or multiple in parallel if you intend to use an MPPT charger on a four-cell stack 12v LFP battery array. You need at least a 36 cell panel for this, or run two or more 32/33 cell panels in series.
There is roughly 0.45v to 0.5v per cell Vmp contribution depending on panel temp. MPPT controller requires some overhead voltage above battery voltage to work properly. Some of the overhead is for the DC to DC converter, some of the overhead is to allow the controller to search for MPPT point. 32 or 33 cell panel is okay for a PWM controller on 12v battery.
Most MPPT controllers will just drop into PWM mode operation if they cannot establish a reliable MPPT point but panel Voc is still above battery voltage.
For MPPT controller, if you are placing panels in series so the Vmp is moderately above battery voltage there is no problem.
Do not use a 32 or 33 cell panel, single or multiple in parallel if you intend to use an MPPT charger on a four-cell stack 12v LFP battery array. You need at least a 36 cell panel for this, or run two or more 32/33 cell panels in series.
There is roughly 0.45v to 0.5v per cell Vmp contribution depending on panel temp. MPPT controller requires some overhead voltage above battery voltage to work properly. Some of the overhead is for the DC to DC converter, some of the overhead is to allow the controller to search for MPPT point. 32 or 33 cell panel is okay for a PWM controller on 12v battery.
Most MPPT controllers will just drop into PWM mode operation if they cannot establish a reliable MPPT point but panel Voc is still above battery voltage.
Normally I would agree with you, but the panel performance values are almost a perfect match.
Normally I would agree with you, but the panel performance values are almost a perfect match.
You are comparing apples and oranges specs. One is for 25 degs C panel, one is for 47 degs C panel.
33 x 0.564v = 18.6v Vmp for a silicon mono cell is not possible unless cells are held to 20 degs C. The Rich spec claims 25 degs which is not realistic with sun panel heating. Maybe in wintertime cold temps. At 47 degs C, which is still relatively low panel temp with sun panel heating it would be 0.516v x 33 = 17.0v Vmp, not the 18.6v listed in their spec.
Renogy lists 18.6v Vmp for 36 cell panel and their spec is for 47 degs C +/-2 degs. That will have about 0.516v Vmp at 47 degs C x 36 cells is 18.576v which matches their spec pretty well.
Monocrystaline cells
OK... sorry, I have not read all of the above because of time restrictions but I do have some comments.
All so called 12V panels that I am familiar with have an open circuit voltage of about 21-22 VDC and Vmp is usually around 18V.
There are good reasons to wire panels in series and that is to minimize the voltage drop in the wires between the panels and the controller. I strongly recommend the OP avoid the pulse width modulation style controllers. MPP controllers are now affordable and allow putting panels in series. The only caution one needs is to understand the so called safe voltages are those below aobut 45V. Think old systems with 48 VDC huge batteries.
I wired my panels (33v) 2 in parallel in series with another 2 in parallel for my boat. Sure, I can get voltages above 70 but I can also get by with almost no voltage drop in the wiring between my total W panels and my Victron controller with two strings of #10 wire.
Thanks for all the helpful replies.
I have an existing lead acid battery bank and believe that my Bogart PWM system was the best system for my lead acid batteries. I am now building a 560 Ah Lifepo4 battery bank and will be installing Victron charging and monitoring components.
Given that Rich solar never replied to my inquiry about whether their 33 cell panels have diodes, and given the uncertainty respecting the actual specifications vs. what Rich Solar advertises, I am going to pursue other alternatives.
Thanks again!
Given that Rich solar never replied to my inquiry about whether their 33 cell panels have diodes, and given the uncertainty respecting the actual specifications vs. what Rich Solar advertises, I am going to pursue other alternatives.
I have 4 Rich 100W poly panels that perform very well. I’m not going to pull one off to pop open the diode/junction box but I’d be shocked if they didn’t have diodes. They play well with 4 WindyNation monocrystaline 100W panels
Can you explain more what you meant by this? Thank you.
The “let-go” voltage of DC maxes out a bit over 50V by ‘definition.’ 40VDC can still kill you but not likely you’ll hold on long enough to do that, though it can burn you.
50VDC isn’t likely to immediately kill you either but it may and is probable it may immobilize you long enough to inflict severe injury- or kill you. 90VDC can shut vital systems down or un-time your heartbeat and may kill you dead on the spot or wack out your body that you collapse dead later or die that night in your sleep.
Is that true all the time? No. Maybe not even close- but the probabilities are a risk factor too great to ignore or take lightly. I can’t remember exactly now (not a joke, it’s just long ago) but 24VDC tingled me once. It was more than a tingle really but I suddenly became more respectful of DC is what I remember.
Check your local Craigslist. People are selling brand new panels out of their garage, half the price of a store. I’m guessing they were surplus from those rooftop solar companies. But DO NOT BUY USED PANELS. They are not worth it as all panels degrade over time. You don’t want them unless they are free, and even then the owners probably just want someone to take their junk off their hands.
OUSHANG SOLAR Product Page
Several years ago I built a small off grid system just to see if I could do. Still works great, except lead acid batteries were the only way to go back then. I picked up some HUGE rooftop panels for a few hundred dollars, all brand new. I had to buy a roof rack for my BMW to carry them home, and they were almost as long and wide as my car. Should have seen the looks I got at stoplights. “Mommy, is that a solar powered BMW?”
Bring a voltmeter with you if you find one of these sellers. Google how to check them, to see if the voltage matches the placard on the back of the panels. Learn how to safely check them, as the large panels will shock you if you’re not careful. You, of course, half to measure them in sunlight, but you might want to throw a blanket over them to make the volt/current connections, THEN remove the blanket.
Contact us to discuss your requirements of 36 cell solar panel. Our experienced sales team can help you identify the options that best suit your needs.
I know you have the AC300, but I noticed that on the AC500, even though it’s rated at watts PV input, the “catch” is that it’s actually watts per each PV input (DC1 and DC2). I don’t know the max wattage/input for yours, but it would be easy enough to split the wattage in half. Of course, in the real world we’re lucky if we get the rated wattage.
I’ve been shopping for more panels, but now that I’ve got the AC500 wired in and running, the one B300s just isn’t enough after the sun goes down. It was down to 12% at 2AM, so it would shut down before sunrise unless I plugged in the AC cord to charge it up to around 40%. We’re in a valley so it gets dark in winter around 4:30 pm, and the panels showed there wasn’t enough sun until almost 6:30 am. I’m waiting on my Bluetti Bucks to use on a 2nd battery.
For more 144 Cell 535w Solar Panelinformation, please contact us. We will provide professional answers.