My solar setup for my AC300 & 2*B300s

I’ve had my AC300 & 2*B300 batteries for around 8 months, and the solar panels I purchased for around 7 months, but I finally completed the solar array installation.

For the panels I purchase twelve used 250 watt panels from Santan Solar. The panels’ data is as follows: Voc is 37.6V, Vmp is 30.3V, Isc is 8.85A, and Imp is 8.27A. I have 3 panels in series and then parallel that with another 3 panels in series, for each of the 2 solar arrays. This gives me a theoretical 1500 watts for each MPPT controller, and 3000 watts total. Each array can give a maximum output of 91 volts and 16.5 amps, which will be regulated to around 1200 watts by the MPPT controller’s current limiting. I would have a theoretical maximum solar of 2400 watts into the AC300 with this setup. I’ve only had this in place for a week so I don’t yet have a lot of data yet, but even on these humid and hazy days I’m regularly seeing around 2000 watts coming in. My system has typically around 50% battery available at 7:30AM, and is full by 11:30AM.

My son and I worked out a mounting system design (he is a welder) that would be used for each array (so we had to build 2 mounts), and would allow the panels to be tilted monthly for the best solar exposure. The pictures below show some of the details of what we built.

Here are my AC300 and batteries.

Here are the posts, with part of the upper tilting mount attached, after they were dug in and concreted in place.

Here is a picture of how we tilt the panels using trailer jacks re-purposed for this job. On the far side of the post you can see the arched bracket. On that bracket the small holes are drilled for each months’ angle, and the bolt is used to lock the angle in place. The large hinge-bolts are also tightened to maintain the tilt position.

Here is a picture of the back of the completed array mounting systems. Here you can also see the flexible conduit and boxes I used to bring the power cabling into the house.

And here is a picture of the arrays showing the front side of the panels.

Here is a couple of screen captures from the Bluetti app showing solar input, taken on different days.


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Man, that is one heck of a cool installation! Do you have pointing tables figured out for the cells? Like, figure out what angle is best for average exposure with an angle indicator for them, so you can set them next year based off of what you learned for the period this year?

That’s some solid work on those mounts!

I used one of the online calculators to determine the best monthly angle for my location. For me the table looks like the following.

Jan: 35°
Feb: 43°
Mar: 51°
Apr: 59°
May: 67°
Jun: 74°
Jul: 67°
Aug: 59°
Sep: 51°
Oct: 43°
Nov: 35°
Dec: 28°

• - 0° is vertical, 90° is horizontal

Since a number of the months repeat there are actually only 7 different angles needed. These angles are also stamped into the arched bracket for reference.

This is the calculator site I used Solar Angle Calculator | Solar Panel Angle Calculator

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Dang, that’s a good setup! It’ll be really interesting to see how it performs. :smiley:

Yes, I’m rather excited to see myself. I still have to change what circuits my AC300 can supply via my transfer switch. I expect to use this to reduce my electric bill, as well as for power failures.

Awesome setup and thanks for sharing the details!

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I’ve been considering the exact same used panels for my setup. Thanks for sharing how well it works for you! Now if I only had a welder in my family…

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This looks so good. If the interface of Bluetti app have the solar angle tips for everyone that would be great. Wonder the company try to add some function that come with weather forecast to inform the user to adjust the solar panel.

Very impressive set up. Thank-You for sharing esp with the pictures!

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Very impressive setup. This is exactly what my next phase of home power capability that I’m looking to achieve and your setup is inspiring to say the least. Are you within city limits? Did you have to deal with an HOA? I know both of those issues might keep me from pursuing your solution, but maybe not. Well done!

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Fortunately for me it’s a “no” to both situations. I live in a rural area so it was no problem for me. I hope you don’t run into any insurmountable issues with installing solar panels at your home.

Thanks for your feedback. Yes, I really hope I don’t have issues with the city or HOA.

Great job. Thanks for sharing your work.

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Just wanted to do a quick update. Today is a decent clear day, so it represents a good winter solar charging day. The system got down to 55% before charging really kicked in. This picture shows solar charging just a little while before getting to 100% full. It is still too early in the morning to get full charging from the solar panels as peak solar would be around 1:00 PM locally.

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Nice job indeed, thanks for sharing!

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Wow! Great setup and documentation! Thanks for sharing this. I am working on doing nearly the same with the ground, 3 panels for 2 arrays on pole mounts…each panel is 75.1"x44.65". I don’t really have access to a welder, so I am trying to configure a suitable setup, but where is material like what you welded purchased?

Can you help me understand the SERIES vs. PARALLEL decision for the AC300?

I have 6*460w panels…VOC 41.52 (3 panels = 124.56v), 13.34a, 460w x 3 = 1380.
(BTW, I do have a 7th panel, but it is for direct connect to the B300…and to have on hand as a spare…but it could be used.)

The AC300 is of course 1200w, 12A, 150V per input.

Over on DIYSF, a member is recommending getting to 8 panels to do 3s2p, but A) I don’t understand it and B) think it exceeds the specs of the AC300. Not to mention, I would have to a day trip to get to Houston to get two more panels, the extra cost, and a more complicated ground array that I haven’t even figure out yet.

So, what would, if any advantage, would I get with 3s2p with an AC300, if even possible? I am not sure the member on DIYSF understands the AC300. Or, should I consider 2s2p?

One other question. I want to get a 2nd battery also. I am tempted to get the B300s. If you were to get another battery for your system, would you spend the extra money to get the B300s? Amazon has the B300 for $1800 vs $2300 (+$108 for the cable) for the B300s, and the official word from Bluetti is they don’t recommend the B300s on the AC300).

Thanks for your time!

Glad to share! Regarding the metal used for the stands, it was my son who got that. Some of it was unused/scrap material from where he works that he was allowed to make use of, but things like the 2x2 metal tubing he had to order new from a local supplier. I’m not sure what sort of supplier to look for, myself.
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So, for the panels, when putting them in series you add the voltage, so 3 of your panels in series would output 124.56 volts, as you noted. Nicely within the AC300 limits. Your This set up is already over paneled since the power out is 1380, which is above the 1200 watts per MPPT controller. The factor that will be limited by the MPPT is the current, which will be limited to the 12 amps max. However, you can still over panel even further if you really wanted to. To do that you would get another 3 panels and put them also in series. Then you would put those two strings of 3 in parallel together. When panels are paralleled then the output voltage remains the same, but the output current is added. So you could use 6 panels in a 3S2P configuration, and the output would have a Voc of 124.56 volts still, but an Isc of 26.68 amps. The MPPT controllers limit the incoming current for charging, so this is not a problem. On a sunny day that would be a “waste” of the extra 3 panels, but on a cloudy day, or even rainy, you could still get close to, or up to, the maximum power input to the MPPT. Then do the same for the other MPPT (12 panels altogether), and you would almost always get excellent solar charging, and this would not harm the solar generator. Quite expensive, but if you live in an area that gets a lot of rainy and cloudy weather it could be the only option. To a lesser extent than this example this is what I have done with my setup. I have six 250 watt panels on each MPPT, so 1,500 watts on each, and 3,000 watts total for the AC300. As for going 2S2P, you certainly could, and would have 1,840 watts per MPPT. Whether that makes sense for the cost depends on your sun availability, and how much of a constant load you will have on your AC300. The higher the load the longer the time to recharge to 100%.
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I have purchased an extra battery for my system, so I have the three. From my reading it seems that Bluetti doesn’t recommend using the B300s on the AC300, as you noted, and it seems to be related to the extra features on the new battery that aren’t usable on the AC300, like the built-in heaters. In my case the unit is in the basement, so freezing is not a worry. The only other difference is the higher current capacity since you can put 3 batteries in series. None of that helps with the AC300.

Have you considered adding electric heating? You could use it to supplement what ever system you have in place, assuming you need to heat your home. Looks like you are leaving a lot of potential power unused. Perhaps you have already found ways to use it more since last posted about it? Btw I think you have a very nice system.

My home has an electric furnace for heating; however, that would take far too much power to run off an AC300 (or even the new whole-home systems for that matter), I have a completely separate 100 amp service just for that furnace. However, I do have a backup forced-air wood furnace, and that is connected to my AC300. So if we have a power outage in the winter then we will use the wood furnace to heat our home. :+1:
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Regarding the potential unused power, that will always be the case. If one is going to size a solar-battery system to run a home or part of the home’s systems then you will always need to make the system have larger capacity than the daily use needs in case of bad weather, cloudy days, etc. So the batteries should be able to store close to 2 days of electric power (you will get some solar even on cloudy/rainy days), and the solar needs to be likewise able to charge well even on cloudy days. So, everything it going to be too large on a nice sunny day.
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Having said that, I do have plans for making changes in my electrical panel and transfer switch to handle more of my critical loads.

Thanks for taking the time to answer all of the questions so thoroughly. I have plenty of sunny days in SETexas, and limited shade concerns. So, I think I will stick to the current plan of just 3s on each input…thanks to your input. I really don’t see over panning is going to be a big concern at this point.
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As for the battery, I am only thinking about if I want to take a battery on the road, leaving the AC300 and B300 behind. But I don’t think the $600 extra would be worth it. Although, BE Admin has responded on another thread, and a directly connected PV would heat that B300s. 5 years ago, I would have said we never go below freezing for more than 10 hours. Then, back to back winters, we have had a blast that killed all of my citrus with sub freezing temps exceeding 24 hrs. So, I dunno. I think I am goi g to wait to see what Prime Day does for the price. Right now…$1800 vs $2400 (including the cord) is a big difference. I can alway get a B300s later down the road when they have dropped more in price.
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Thanks for your time!

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