Best Panels and array config for AC300

I have an AC300 and eight Renogy 320W panels. I am now realizing, after a good amount of experience(isnt it a great teacher), that these panels may not be the best for maximizing the solar input into the AC300. I would love to hear what panels other people are using and the array configs so that they can maximize their solar input. As it stands I can truly only best use 6 of them without hitting the amperage max. Thank you

Renogy 320W Solar Panel
Voc: 40.1V

I have three panels in series and two series in parallel. That gives me 1600 watts and my ac200max only needs 1200 upper limit. The question is how many batteries do you have?

We have two B300 attached to the AC300. I have three in series on each of the two array lines for the AC300. We had it setup as a 2S2P but it was hitting the amperage max and limiting the wattage to 800W instead of around 1200W.

The AC300 can handle two separated PV inputs. The DC cable has two sets of MC4 connectors well labeled. So you can add panels to supply up to 150 VDC in series on one MC4 set and supply another group of panels in series on the other MC4 set. It seems that the established limit is 8 A on any PV input so in theory, the AC300 can take in two DC sources of 1200 watts. Just be sure that the sum of the panels never exceeds the 150 VDC of the PV inputs.

I did some reading after I sent the email, instead of relying on my memory. I had it in my head that it was a 16A max and not 12A as it really is. I have figured out my issue and am working within the parameters that I now have correctly stored in my brain. Thank you for your time and I am sorry for wasting your time.

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No time is wasted if it helps someone here.

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Is it max 150v and 12A for each of the 2 inputs (but limited to 1200w each)? Or only 8A for each of the 2 inputs?

Each of the Array inputs can take up to 12A and 150V. The “max” wattage is 1200w but you can over panel and ensure that you are pulling the highest amount for longer.

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I’m using 9 320w 42voc panels. I have them in a 3s3p pattern with fuses. the working voltage is about 105v, and the voc is 126(below the 150 max).

they are a long way from my cabin so I run a single pair of cables to the cabin, then split the cable with a “y” connector installed backwards, and plug the 4 y ends into the two mc4 channels on the ac300. I can get 2000w input on a nice sunny morning. that’s pretty close to 10 amps per channel.

I think you might be hurting yourself a bit there. There is a max Amp input of 12A and your series is putting out roughly 7.6A. As soon as you put those series in parallel you increase your amperage beyond what the charge controller will take, thus limiting your wattage input. Voltage is additive across a series and amperage is additive when going in parallel. So instead of getting the theoretical 2880W from your panels you are limiting yourself because of your amperage. This is the thing that I learned just last week, and it was the not fun way. I was upset because I was only getting about 800W per array, totaling around 1600W total from my eight 320W panels. I had them set up in two arrays of 2S2P. This was busting my amperage limit and thus lowering my wattage input because of that. I change my arrays to be 3S1P and am not pulling in more than I was before and using two less panels. I hope that you don’t find what I am saying as critical I am merely trying to help you get the best draw out of your panels.

What I have are 12 used Santan 250 watt panels. I don’t have my mounting system yet, so I set up 6 of them in 3S2P on my lawn, as I intend to set up each set (I will have 2 set of 6 panels set up as 3S2P) so that I could test their performance. Vmp is 30.3 volts, Voc is 37 volts, Imp is 7.78 amps. These panels are working out great, and I’m quite happy with them (I expect the other 6 will perform similarly).

Each set of 6 will give me a max power with 90.9 volts and a maximum potential of about 15 amps and 1500 watts. However, each MPPT controller is limited to 12 amps, so basically I am “over panelling” each controller, and I am happy for that. This allows me to get the maximum 1200 watts in (per controller) for a longer period of time during the day, and better charging performance on less-than-full-sun days than if I had perfectly matched panels (ie: 1200 watts of panels).

This test also confirmed something that I has suspected regarding solar panel performance. Panel output voltage is not a fixed number. As with my panels the Vmp is 30.3 volts, and Voc is 37, and this already shows a voltage range for the output. As the AC300 begins to limit the current from the panels to 12 amps the voltage from the panels begins to rise. For example, with my panels if the voltage remained at the 90.9 volts (Vmp) at the 12 amps I should only get 1091 watts in. However, I have seen as much as 1219 watts coming in (yes!!!). When I checked the AC300 display the voltage was over 101 volts. Also note these are almost flat, certainly not at an optimal tilt. It’s going to be great having all 12 panels connected.

So, over paneling is a good thing to have as long as the maximum 150 volts input is observed.

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Woah, you use a y split to connect both MPPT input to the same set of 3p3s panels? Would the two MPPT input of the AC300 fight each other? I though that has always been a no no to connect more than one MPPT to a single panel set.

I suppose the y splitter may not be exactly optimum for mppt tracking, but I figure it’s close enough. each mppt will allow a certain amperage in, and the whole array will see the sum of the amps let in. one or another of the sets will not be at the mppt point on the curve, but probably close. the panels are all grouped together with an optimizer on each one.

it seems to work just fine. running an extra set of 200 foot cables just wasn’t worth it to me.
please let me know if I’m way off…

Well, you have proven it to work. It was one of those things that everyone says don’t do it. But in your situation, it seems OK.

GP- no criticism taken. I’m at a loss though- I agree that perhaps I could get similar wattage with fewer panels, I still do like the overpanelling aspect for less than ideal conditions. the way I figure it, you put as many panels as you can in series staying under the 150v limit (I can’t use 4 in a row) to maximize the voltage aspect. then put as many in parallel as you can afford to increase the amps part of it, up to or over the max allowed by the mppts. sometimes you might waste some, but on other cloudy or winter days you will have more than you would otherwise.
also, one will never see the nominal wattage rating from each panel as that implies you are at the equator on Jun 21st at 12 noon, with no humidity in the air…

In the AC300 there is a setting to parallel the two PV inputs together. I think that setting should be turned “ON” when connecting a single array to both inputs.

Screenshot 2022-03-23 084326

I just bought a AC200MAX. I am thinking of just using (4) 200 watt panels for it, wired in series. The panels I have are 24.3 volts each - short circuit Isc is 10.2A, Imp is 9.80A & Vmp is 20.4V. I know the MAX has an input limit of 145 volts which I am under. The watts are 900 max which I am under. My wire run though will be 150 foot from the house. I am using 8 gauge wire. I know the above system will work, but am wondering if I could add a 5th 200 watt panel. Anyone know? Just want to be able to add as many as I can, but with the long cable run, I don’t know how it will act. Panels rarely put out what they claim, but when things get cold, voltages etc. can go up. And here in Minnesota, I spend several months in below 30 degree temps.

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With 5 of those panels in series your array Voc would be 121.5 volts, which is in the limit of the AC200max. The Vmp would be 102 volts, and the Imp would be 9.8 amps, which would provide 1000 watts max. The fact that the wattage is over the AC200max limit could mean it will limit the input to 900 watts. This setup should work fine for you. The fact that this is “over-paneling” your system means you’ll get better performance in less-than-ideal circumstances. I would do it. :+1:

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Many thanks for the input. I was hoping to get the 900 max, but was unsure on the setup. I know having 6 put me at 145.8 volts which is over what the max could handle, so was not going to do that even though I wanted to as the set up I am designing works better with pairs rather than odd numbers, but then besides being at .8 volts over max input, I would also be at 1200 watts which would be way over. The 5 panel idea is a better plan I think.

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I agree that the 5 panel idea is a much better idea. I had a similar thing with going from 8 panels to 6 and getting better results because I was pushing the Amperage max. “Over-paneling” is great in the sense that you are getting the max amount of watts for longer in the day and in bad weather. However, to “over-panel” properly you have to stay under your voltage and amperage limits because if you don’t then you will be limited and get less than you would have with fewer panels. I like that you have a solid plan and are testing things out. I also have an AC200P and a AC100, which is no longer even made. Keep at it everyone, this is quite the fun and liberating thing to enjoy.

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