Beginners Guide to Processing 18650 Cells | Cell Database

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Upstate NY (USA) Build
I run a small consulting business out of my house and am looking to get it off-grid. Mostly due to a desire to learn how it all works.

Energy consumers:
  • Dell R620 Server (VMWare) 4.47Kwh/day
  • 2015 MBP with dual 34" monitors
  • 2016 Lenovo with dual 24" monitors
  • Speakers
  • LED TV
  • Printer
  • Scanner
  • LED lights
  • Mitisubishi Mini-split (this won't be switched over until I understand more of its energy demand -- I'm sure it's a lot) It's also 240VAC
Without the mini-split, I'm estimating a max of 10kwh/day. 

  • 80p7s (Thanks, Pete!) x 5
  • Batrium BMS Starter kit with 21 additional longmons and 375A shunt
Charge Controller/Inverter:
  • MPP Solar 2424LV-MSD
  • 6-9 Canadian Solar CS6U-340M (340W Mono) 37.9V
  • TODO: Figure out the wiring setup of these (how many in series and then parallel)
  • TODO: Figure out whether to roof mount (hate putting holes in a roof) or ground mount.
Missing Details:
  • Where and what fuses/breakers to use?
Am I missing anything? Any suggestions?

This community is awesome and I could not have gotten to the point I'm at now without you. Thank you!!

First of all if you go with Peters style (Same as mine) its 7s80p Wink

Wiring: Depends on the voltage of the mono but it should work with 3s. Ie 3s2p or 2p3s... 6panels max on that inverter.

Fuses/breakers: Use 2 pole for battery and solar. Use DC rated ones. 124A DC DIN mounted fuses should work for that current.
Use proper fuses before the inverter and after including breakers.

Also note that for 10kW of usage and if you plan that offgrid. How much sun do you have in winter? Where I live we have 10% of what we have in summer. We can also have several days in row of bad weather. In bad weather you either need to have xx amount extra energy or large battery bank.

My bank can hold me for 5+ days without solar. Thats minimum. 7s80p wont get you more than 1 day unless you have 3.5Ah cells Smile On 2.5Ah its around 5kWh or something.

If you check my layout you will get an idea on what I use in terms of material. Same if you check Peters you get a hunch on what he used.

So to sumarize:

1. You need alot more panels and battery capacity to be able to go offgrid with 10kWh per day unless you have darn good sun Smile
2. 6 panels max on that PIP if you want to use it all
3. Dont forget trip shunt on the battery. Batrium sells matching of those that will work perfectly fine to your system. Both breakers and the trip shunt!
4. Take a look at mine and Peters design and components used and then scout ALL others Smile
jamesk9 likes this post
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Thanks for the quick feedback!

I probably should have mentioned that I'm planning on 5x of the 7s80p (I also goofed on the order. Seemed to make more sense that I hooked up 80 in parallel first before the 7 in series). Still learning the terminology. That'll give me 25kwh to start.

The panels are 37.9V (optimal).

Darn, I just placed the order with batrium and didn't get the breaker. I did get the shunt kit and the additional longmons/cables needed. I wonder if they'll let me squeeze it in there before shipping.

Any links to the breakers/fuses I should be using on the rest of the system? I'm 110/120vac 60hz and the DC voltage will be 24v (for now).
Yes you do 80 in paralell then series. Its just the order of the s,p that is in oposite Smile

Email Jaron and he can probably sort that.

Depending on legislation where you live the breaker Jaron sells will be working for the solar too. Though for battery you should get the shunt-trip as well. Just check that out first.
Since you are in US im not going to link specific stuff more than you can check what I use. Smile
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Still noodling the breakers needed. I'm planning on hooking the panels up in 3s2p. ISC is 9.48A. So that's pretty much 19A. I read somewhere that to calculate the size of the breaker between the PV and the charge controller you need to multiply the max current by 1.56 and then round up to the nearest standard size breaker. That gives me a 30A breaker.

Breakers that I believe I need:
- Between panels and charge controller - 9.5A * 2 * 1.56 = 30A (DC) -- possibly times two for roof shutoff and closet shutoff
- Between batteries and inverter - 2400W / 24V * 1.25 = 125A (DC)

Pete's diagram has so much more. Am I missing something?

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