After the 3000 watt solar limit of the ac500, does solar charging through the B300s (within specs) increase the total overall charging ability beyond 3000 watts?
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I’m finding that solar charging all 4 batteries (while powering the house) is taking all day, and if it’s somewhat cloudy they won’t reach 100% before the sun goes down. So can I start adding panels to each of my 4 batteries (within the specs of course).
You can add new panels directly to the B300S charging port and its included MC4 cable, but it is limited. I have two unused 100 W PV panels connectled directly to two of my B300 batteries to assist charging but my AC300 will only see the SoC, not the power coming in. This is a work around which is great if you do have extra PV panels. See your B300S user guide for the PV specifications.
It’s surprisingly hard to find and add panels that will fit into the voltage/current match of my current system, without hitting the 1500 watt, 150 volt limit of DC1 and DC2 inputs.
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My DC1 array has 12 100-watt Renogy panels (in two strings so the voltage doesn’t reach the 150 volt limit), but it seldom comes close to 1200 watts total. 1138 watts is the record high while it’s mostly 1000 to 1100 watts. What I’m thinking is adding 2 more 100-watt panels, one to each string of 6 panels. That’s going to put the voltage at 142.8, close to the 150 volt limit. Even then I’ll likely get only +1300 watts total.
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As for the other DC input, my choices are 2 550-watt panels for 1100 watts, 3 400-watt panels for 1200 watts, or 4 320-watt panels for 1280 watts (but they are too big for my array.) I just can’t find an easy way to get close to the 1500 watt input limit.
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Amazon has a great price on the 550 watt panels, and I would just plug my old panels directly into the B300s inputs as each are within the battery input specs.
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So the battery inputs are separate from the 3000 watt limit of the ac500, right?
I can only squeeze 2 Kw max out of my arrays, and even though I get over a kw as early as 7am, and several hundred watts as late as 6pm, 11 hours of sun is barely enough to recharge all 4 batteries to 100%.
It is a common misconception that you need to current match, it’s not true. There’s a concept known as over-paneling where you stay within the max voltage range of your MPPT controller but increase the total current your solar arrays are able to generate by wiring groups of panels in parallel. This will let you easily hit the 1500W max.
Volts are pushed from the panels to the controller but the controller pulls/requests amps and only as many as it is designed to support (15A for each of the AC500’s MPPT controllers) even if the panels COULD supply more current in ideal weather.
Side note: when calculating your array’s voltage to see if it’ll exceed the controller’s range you MUST add the panel’s open-circuit voltages (Voc), and not the panels’ voltage at max power (Vmp or as Renogy calls it, Optimum Operating Voltage). This is because you want to use the system’s highest possible voltage. Secondly, the system voltage lowers from Voc to Vmp as the controller pulls amps
Here’s an over-paneling example. Assuming each of your 100W Renogy panels has an open-circuit voltage of 24.3V, a max operating current of 4.93A and a maximum series fuse rating of 15A. Six panels in series result in an open-circuit voltage of 145.8V while 5 panels in series results in 121.5V (the Voc will be lower at hotter ambient temps and higher when colder). Each configuration will show have a lower operating voltage of around 121.8V and 101.5V for 6 and 5-series arrays respectively. I assume you have two sets of 6-series arrays wired in parallel today for DC1. You can over-panel by simply adding a third identical solar array of 5 or 6 series-wired 100W panels and combine it with the other two arrays using 3-way parallel adapters - this would be summarized as a 6s3p configuration (6-series, 3-parallel) with a total system power of 1800W. What I recommend is going with a 5s3p configuration totaling 1500W so you’re not as close to the 150V limit. If you want to add one more panel for a total of 16 then you’d have to go with 4s4p for 1600W.
Note: All your array strings should have the same number of panels and thus the same combined voltage.
If you apply the above concepts for your DC2 solar array then you’ll see that you’re not as limited as you think.
Well, I have two more 100 watt panels coming in today. I plan to try two strings of 7 panels, since 2 strings of 6 are a disappointment, producing only 1000 to 1130 watts, even on the best days, (even now it’s showing 1023 W at 104.8 V on a clear blue sky day, aimed directly at the sun and my array is directional.)
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I know “officially” we’re supposed to use Voc instead of Vmp, but in the real world the panel output voltage falls short. It’s to give you a safe “headroom” of output. After mounting all the panels, I checked each one before connecting them together and got between 21.3 and 22 volts. So for series strings it will be the lowest panel voltage of the string. And in parallel, output will be the voltage of the lowest string. I just don’t see Voc happening.
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If it causes an overvoltage warning, then my next step was going to be the 5s3p with 15 panels, (so I’ll need yet another panel.)
Getting 100% of your panel’s rated power output is rare to achieve practically. 80-90% is really good and 70-80% is typical for most on a clear warm day. The solar panel manufacturers of course might make you expect otherwise.
Ambient temperature plays a role in the actual Voc with being lower than the specs in summer and higher in the winter with the colder weather - it’s not to give you headroom. The reason most use Voc instead of Vmp is because the MPPT controller will not start pulling current if the input volts exceeds its max, even if the Vmp is much lower. However, you can “trick” your MPPT to ignore Voc by always having it connected and so it may never receive Voc. The one exception I can think of is if your power station reaches 100% during the day and no more current is pulled. Once you use up some battery it may throw an overvoltage error if the input voltage is above 150VDC.
I have the following setup and it works great for me. I have the following panels.
https://a1solarstore.com/znshine-solar-405w-solar-panel-108-cell-zxm7-sh108-405-m.html
4 panels wired in series connected to dc1
4 panels wired in series connected to dc 2
4 panels independently wired to my 4 b300s battery
I have hit 3000 watts input but voltage always has been in safe spec for the 2 arrays. I have manually tested the individual panels connected to batteries to make sure they are being used but still looking at an inline power monitoring solution. On a sunny day this week I went from 10% to 100% by 1 or 2pm and stayed at 100% until about 6. I was running about 900watts off the inverter the whole day at same time.
Today was overcast all day and I got up 65% from 20% wile running about 700watts all day
Hope this helps some.
I’ll be adding 200 watts to my 1200 watt array, and replacing some old panels with 1280 watts (4x 320 watt panels) on my 2nd array on Wed, then move my old panels to wire directly to my 4 batteries. Hopefully, this will do it.
Currently, I’m lucky if I get to 50% SOC by noon, and 100% by about 5:30 pm. I’ve had to resort to Grid power a few times when it stalls out at 95% when the sun goes down. Getting all the batteries back to 100% seems to reset them so they charge/discharge more equally.
@St8kout
You can add solar panels to charge the battery pack, although the AC500 will not display the input power of the pack.
Yes, but it will still add to the total SOC of the whole system, right?
Okay, you convinced me, 5s3p is the way to go. Just ordered one more Renogy panel to add to the array. This thing is turning into a huge monstrosity that’s been catching the neighbor’s attention. It creaks and groans when I re-aim it every night for the next morning’s sun.
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It’s built from Superstruts, (also goes by other brand names like Unistrut) but they are really strong and easy to build whatever you need. You could throw up a free standing structure for something like overhead stage lights for a band in minutes. It’s “tinker toys” for adults 
You’re re-aiming your panels daily? Sounds like a lot of work. Maybe with the new config that’ll become obsolete. Let us know how it comes along!
This is will increase the input power of the whole system, SOC refers to the meaning of power.
My solar farm was only putting out 2kw so I built an angled “see-saw” type mount, where it easily aims east-noon-west. I could mount an antenna rotator to the center rotating pole to do it from inside the house, but the cheaper rotators ($120) don’t last. They have a plastic gear drive. I’d have to buy a more hefty model but don’t want to spend over a grand.
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Just swinging it from “noon” to the suns position at 2-3pm gives me 200 extra watts. I’ve verified this multiple times. In the morning position I start getting 1kw at around 7am. 6pm is when the power goes down to <100 watts. So every night I reposition it back to “morning.” Not a big deal.
That sounds really cool! Would love to see your setup.
It’s a simple but effective setup.
Imagine a right triangle. The hypotenuse is the rotating pole (Superstrut bar) that cross bars (more Superstruts) are horizontally bolted to.
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The vertical part of the triangle is a post anchored in 2’ of concrete. The post is simply 12’ long parallel 2x4s with a space between them. The “hypotenuse” sits in the space between the 2x4s on a block of wood attached to the 2x4s. It’s free to rotate. The other end of the “hypotenuse” sits on the ground. I bolted a right angle piece of metal (Superstrut hardware) to the end between the 2x4s so it doesn’t slide out. I did add an X brace underneath to the “hypotenuse” because of all the weight of the panels and cross bars.
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Obviously the proper sun angle can be set up and changed, by lifting up the ground end with cinder blocks or whatever. Mine is set to the ‘year round’ angle for my location.
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I’m still working on a way to lock the rotation where I want, as windy days will change it. I’m using bungee cords at the moment. This is where an antenna rotator would be handy, mounted on the either the ground end or to the vertical 2x4s.
So I finished adding 3 panels for 5s2p setup. I’m not seeing as much an increase as I thought. 1303 watts from 1500 theoretical watts. Before, with 12 panels I’d see readings in the 1100s. Adding 300 watts for <200 additional watts? If one of the wires broke in a string that would leave me with only 10 panels so my readings would be much lower, so that’s not the problem.
They don’t make Superstruts longer than 10 feet, so I had to resort to a 12’ 2x4 for the bottom cross member.
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There is some high level clouding but the power output is steady, not fluctuating as from passing clouds. I’ve got other panels to install separately from this, but I’m too sore from all the work on the first array.
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Hard to say but I’d collect max power data over more sunny days alongside the ambient temps before drawing any conclusions on your 5s3p setup. Also, if you meant to upload a picture to your previous post it didn’t work.
I’m at a loss as to why this pic won’t post, as I’ve posted other pics here. I even tried to copy/paste and here’s the result?
cid:E09BC195-30C0-4FF7-883D-BA47D7D9721A
Let’s try this:
Strange I could post this from my ipad but not my Macbook.