Thanks for the great info:
I decided to possibly go for the 410-watt panels instead.
With the lower VOC, I can get 1230 watts of panel power for the AC300 ( of course you never get what they say)
but it keeps me at 111.36 volts & 13.96 amps when wired in series.
410 watt panels
VOC is 37.12
ISC is 13.96
VMP is 31.35
IMP is 13.08
The problem is when you buy these big panels from anywhere, you have to buy 10 minimum.
I am installing a 240-volt system next year and I need some of these large panels as I only have so much room on my roof, so need to go bigger wattage, not more panels.
So will be buying “X” amount of the large panels for that system & those will have to be the same panels I buy for the AC300 upgrade & the Max upgrade.
That way, I can just get a pallet of those panels. I also want the panels to all look the same on the roof & my brkt system dictates that also.
So that is why I am trying to make this work. I know what I need for the 240-v system, but need to figure the same panels (whatever ones I use) and make them work for the
AC 300 & Max. With limited roof space, I need to get the biggest panels I can as my 240v system can take up to 7500-watt pv input with 500 volt & 27 amps.
So will be getting 12 of these 410w panels, which puts me at 4920 watts, 445.44 volts & 13.96 amps. So that is good. Then need to figure the same panels to the bluetti units.
You got me thinking, so that is good. Deciding on the 410-watt panels work better for the AC300 & also allow me to put 3 more panels to my 240-volt system also. Could only use 9 with the 455-watt panels.
Thank you so much!
I did see photos of your ground array, very nice!
I attached some photos of my ground array.
The panels look blue in the first pic, but they are black.
take care
I am using the Renogy’s 450W (I got them earlier this summer). 3 for each PV leg. They were unavailable most of the summer, but just became available online. I got mine from Home Depot but they were unavailable there last time I checked.
VOC=41.25
On the Sunny days, I am getting 2400W (2375-2430W) for an hour and a half window. I can charge 4x b300 batteries about 50% on a typical day. They are slightly overpaneled but that allows me to have that longer period of max input (around 2400W).
I really appreciate your post
…completely new to solar, and I am no electrician.
Changed outlets & light fixtures …that’s about it
…just purchased the AC300/B300 combo and I want load it to capacity with panels
… very interested in the 250 watt Santan panels you spoke of and I found some used ones at $40 apiece
…thinking about buying 12 of them
Forgot to ask
…The Santan panels I’m looking at specify they have a Max power current of 8.27 A ,
…but they don’t specify the IMP
…I’m assuming these are same panels you spoke of?
Those, by the specs, appear to be the same as the ones I bought. And FYI, the max power current is the same as the Imp, so you’re good with that information. I am very happy with these panels. On a day with sun, even somewhat hazy sun, I’ll get anywhere from 2,200 watts to 2,400 watts during peak solar hours with the twelve panels I have.
I don’t know much about it,
….but I heard you guys talking about temperature affecting voltage maybe ?
…so knowing that you are in the same climate is helpful.
Yes, higher temperatures reduce solar output from the panels, and cooler temperatures will increase the output. It’s a helpful feature during the winter months when there’s less sun hours in a day, but the cooler temps helps the performance.
If it helps, here’s my post that gives some details about what I have set up, and that might give you some ideas. I have added updates for the current set up.
I think my solar panel location is going to give me about a 200 foot run to my house.
Do you think I can still get away with 10 AWG?
Also I was noticing in your earlier post that I might need to use a breaker where the line goes into the house maybe?
And I saw that you had posted this one.
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…I was wondering if that’s what I should do
…and I am assuming I need to put in a copper ground rod by the panel array and ground them
…do I need a fuse box anywhere …I would assume the breaker takes care of it
I’m really trying to understand every component since this is new to me
I ran two sets of cables, one to each of my solar arrays, and then have them each directly connected to one of the MPPT solar inputs (ie: I don’t use the parallel mode). So one cable length is approximately 125 feet, and the other is 150 feet. I used 10 gauge wire for each, since there is a maximum of 12 amps on each set (limited by the AC300). I would go ahead and use one of the online DC voltage wire length calculators and see what voltage drop you get between 10 gauge and 8 gauge.
I did put in the DC breakers (these are different than AC breakers since DC can generate considerable arcing, and DC breakers have arc suppressors) so that I could disconnect the panels easily if needed, and for the current protection. They are good to have.
I do not have my panels grounded, although they are mounted on a steel support structure that is dug 4 feet into the ground. I do not assume that will ground them properly. There does not seem to be any agreement regarding what size solar array needs to have grounding, but clearly there would be no harm in doing it. We do use grounding rods for our solar-powered electric fence controllers though. For those we buy 6 foot copper ground rods from Tractor Supply, and believe me, my electric fences work GREAT!
There’s a considerable learning curve to the whole solar panel use, that’s for sure!
Thanks again.
Yeah that’s the same way I’ve been using copper rods.
I’ve been using the 6 foot copper rods for ground on horse & goat electric fence’s also.
Thank you @chemosabe99. I found your description to be a very concise summary of a sensible strategy for panel config. I hadn’t come across this rule-of-thumb serial → max volts, then parallel → max amps strategy before, but makes a lot of sense to me.
Thank you for all the great input!
I have two ac300 and am looking at using two sets of three 390w panels for each one.
VMP 30.4V
IMP 12.69
VOC 36.4
ISC 13.55
I have nothing that uses 220 volts so I will use one to power my garage and the other for mu house.
Hello everyone, I have 10 330W panels connected to an ongrid inverter. I would like to share the same panels to power the AC300. Is it possible to connect two cables to the third and sixth panels and use them at the same time on the AC300 inputs? This way I would have two circuits with 3 panels each. Thank you very much in advance.
In my understanding of the way solar panels work, and how MPPT solar charge controllers work, you basically cannot connect one, or one set, of solar panels to two MPPT charge controllers. The reason for this is because solar panels do not work like a battery, where there is a relatively fixed voltage output, and you can parallel them to pull more current. Solar panels vary in both voltage and current depending on the amount and angle of sunlight hitting the panel, and to a lesser degree on the temperature of the panel (colder being better). Also, the voltage varies with the amount of current being drawn from the panel, as the current is increased, the output voltage decreases. So, a MPPT charge controller is going to determine what the panels’ instantaneous maximum power is by regulating the current being pulled from the panel and seeing how the voltage changes, and then determine what is the maximum power that can be taken. And it does this very quickly and continuously. So putting two such MPPT controllers, trying to do that same thing simultaneously on a common set of panels doesn’t work because they will interfere with each other’s operation.
Having said that, I am certainly no expert in all the technical aspects of solar panels and MPPT charge controllers, but this is based on what I do know.
Enjoy your project.
And if you have questions, ask away! There’s quite a few here with the experience to answer! 
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