Design Qs part1 for 24v system with Bluetti EP500 Pro

[Kapow_Network]

Well, I almost started the headline with Dumb Question #1... nube here.

I need as much juice as possible to go into a Bluettii EP500 Pro that I bought via kickstarter (of course, anyone can easily point out that it might have been better if I bought the Ecoflow Delta or some other system that came out later, or just used a DIY Blueprint, but I needed batteries anyway. So at the price point, not just Hobotech, but the specs it seemed like Bluetti offered a lot of value. Details here

BLUETTI EP500 & EP500Pro - The New Era of Home Backup Power

5100Wh LiFePO4 /1200W or 2400W MPPT Solar /Seamless UPS /240V Split Phase /6000+ Cycles /App & OTA Upgrade /100W USB-C /Charge Tesla

www.kickstarter.com

Note: important to distinguish the EP500 specs from those of the EP500Pro. So far as I know neither is available on Kickstarter anymore.

I'm also trying to pair it with 1 - 3 (depending on whether parked or moving) REC 350 TP2S72 panels (350 watts).

Basically, here is a diagram with specs:

1 - 3 panels [REC 350] with each one carrying:

... VOC 46.7 v
... VMP 38.0 v
... ISC (short circuit current) 9.40A
... Nominal power currrent 9.00 A
.... Max System voltage 1000 vdc
.... Fuse rating 20A
... IP67 junction box with bypass diodes

| - connection wires (MC4? but the panel specs say
|
Tonglin TL-Cable01S-F (4 mm²) (1500V)
Tonglin TL-Cable01S-FR (4 mm²) (1000V)
|
| - guessing these are one manufacturer's models for an MC4? And any MC4 wire / 10 awg will work to connect the panels?

I may need to rotate or move the panels a bit, so I was thinking I might need to custom cut 2 - 4 feet of wire between each panel.


*** ? Controller or other device needed here? ***

Bluetti told me an MC4 (Anderson I believe) will go into it's all in one

EP500Pro.

The specs on the EP500Pro ( from almost 2/3rds down the kickstarter page listed above) are:

PV or T500 input = 2400w max
35 - 150 vdc (looks like at 46.7 my panel meets this; but is my panel too strong for these figures below?
So I thought it had a built in controller, but now wondering if I need a step down device or perhaps I should get a different panel or set of panels ?)
12Ax2
12v / 24v, 8.2A

====
I'll try to also post a diagram / sketch soon in case that helps show what I'm trying to do.
Thanks in advance for any help.

 

[Kapow_Network]

For those who want to see more of a diagram of the main pieces (panels ---> all in one). Here's an initial diagram. Irony is that, not including the wires, I don't know if a third piece of hardware may be needed to not break the EP500Pro.

I was going to ask Santan solar if they could chip in some extra MC4 wire with the panels (is this usual to do?). Or should I plan to buy a separate spool?

Also, appreciate I will check and see if Will recos a tool for cutting, stripping, and crimping MC4 wire. I just saw one online for appx $300! I hope to find a tool that's far cheaper than that.

 

[Kapow_Network]

Okay - major mistake on my part: I haven't clearly thought out whether the 1 - 3 solar panels will be wired in parallel or in series.

If possible, I think I want to wire in series.

If wired in series: "When you wire multiple panels in series, their output voltages add together, and their output current remains the same." So I think the VOC of 46.7 (1 panel) to 140.1 (3 panels) is fine. BUT if "Max power current" for each panel is 9.00 Amps, then even though the current stays the same, would I break the Bluetti because it seems to have the option to input

- 12Ax2
or
12c/24v, 8.2A

Clearly 8.2A is below the 9A.
I'm just not clear on what is meant by the parts below in bold and italics.

35 - 150 vdc, 12A x 2
12v/24v, 8.2A

While I think it would make sense to run a 12 or 24v system, if the 8.2A is the max it the EP500Pro can handle, then 9.0 amps from the panels might break it.

At this point, I'm going to email Bluetti before I place my order for the panels. Sorry to have posted on this (but thankfully it appears on one was bothered by providing an answer .

 

[Kapow_Network]

Also I'm starting to see how I lot of the sizing issues might be resolved with calculators / tools already here on the site: Eg - regardless of what the manufacturer suggests, weather is a variable for which I may need to make a calculation. Thanks @upnorthandpersonal for

Maximum open circuit voltage calculator

I'm posting this in a thread here since it might be useful for people. Please keep in mind that the below calculator contains bugs and doesn't do error checking - it's literally been 5 minutes to put together. Ok, so what does it do? It calculates the maximum open circuit voltage you would see...

diysolarforum.com

 

[Kapow_Network]

Okay, for anyone struggling with the EP500Pro this page
https://www.kickstarter.com/project...p500pro-the-new-era-of-home-backup-power/faqs

seems to answer many of my questions:

Can I use third party solar panel and what conditions need to be met?
https://www.kickstarter.com/project...-of-home-backup-power/faqs#project_faq_355712
Yes, you can. However, it must meet：
1)Open Circuit Voltage(OCV):
• EP500: 55-145V/Max.20A, Max.1200W.
• EP500Pro: dual MPPT，each is 35-150V/Max.12A,1200W Max. (2400W Max. For dual connection).
2)Suitable MC4 connector.
3)We recommend that the solar panels to be connected should be of the same brand.

NOTE: I've emailed Bluetti and pointed out that in the current version of their manual, I don's see such a clear distinction
on the capacities of the MPPT controller as listed above on the kickstarter page.

I've suggested they consider and creating 2 SEPARATE MANUALS as, at least in this area, they're very different models.

And it appears an earlier email from a rep (mistaking one for the other) threw me off big time
(and that helped lead me to post here and try to understand if I needed yet another controller than the built-in one).

Waiting to hear back from Bluetti, but for now, I consider the kickstarter page I posted to have BETTER data than the manual.
For any who need it the manual appears available from Bluetti at

https://cdn.shopify.com/s/files/1/0536/3390/8911/files/BLUETTI_EP500_USER_MANUAL.pdf?v=1627884742

 

[Kapow_Network]

So perhaps manuals are available for the Bluetti AC300 and/or older tools, but a few days ago when I checked the Bluetti site, no manual was up for the EP500Pro (only the EP500 which is different). In case anyone finds it helpful, I'm posting the one that I was just emailed. Also, if anyone has more info on the controller(s) that Bluetti typically uses (and their specs) I'd find that helpful. Also, their support did confirm that the EP500Pro specs I listed above should be correct ( and a rep may have made an email mistake earlier). So far Bluetti has been fairly responsive and I appreciate that.

Note: I might need to travel with the unit. If anyone knows of a good cushioning method to reduce vibrations (other than packing foams), please let me know.

Also, while this may sound weird, I'm thinking that if their is a big old microwave, or some other type of EMF shielding, it may help make it safer for people to be near it for extended periods. Specifically, if anyone knows of EMF shielding being BAD for the components of a controller / inverter / batteries etcera, please let me know. Unfortunately, the thing is fairly big, so it's not easy to shield PLUS leave room for ventilation. Again, arguably these are "1st world problems" and but I've seen some things lately. I'd rather consider options to over-react / prevent cancer than to cure it.

 

[Socktop]

I purchased the same system as you on Kickstarter! Everything is still 100% in its original packaging. Was waiting on our cabin to be built, now that it is almost ready, I am ready to install the bluetti ep500m pro (have two). I want to use solar panels fixed on a roof to charge the system and looking for anything or anyone to help me put it all together. I want only to buy the best solar panels, wiring, etc, to best work with the bluetti ep500 pro. I also would like a simple diagram to follow. I am a newbie. If you or anyone can help me, or lead me in the right direction, I would be very appreciative. Moreover, I am more than happy to pay for the consultation needed to install this system. Can you help me?

 

[Kapow_Network]

I purchased the same system as you on Kickstarter! Everything is still 100% in its original packaging. Was waiting on our cabin to be built, now that it is almost ready, I am ready to install the bluetti ep500m pro (have two). I want to use solar panels fixed on a roof to charge the system and looking for anything or anyone to help me put it all together. I want only to buy the best solar panels, wiring, etc, to best work with the bluetti ep500 pro. I also would like a simple diagram to follow. I am a newbie. If you or anyone can help me, or lead me in the right direction, I would be very appreciative. Moreover, I am more than happy to pay for the consultation needed to install this system. Can you help me?

Hello - sorry I haven't logged in regularly for awhile and I just saw your post.

I also had some set up delays as I had to design special mounts.
Now I too am looking for a simple diagram or video (and realize I need to re-check this site as by now someone may have posted on this).

Did you ever get yours set up? If you can share your experience that would be great.