diy solar

diy solar

Pls help me with system design

The BMS determines the discharge rate. So yours is 120A. So you really don't need wire and fuses for 200A. I would still use 2ga wire and a 200A fuse, though. My SOK BMS says it is 100A / battery and I have pulled 115A for 10 minutes from it when I had the microwave and residential refrigerator running at the same time.

120A @ 12V is 1,440W. That should be plenty to operate your 1000W inverter and some other basic DC loads. Are you planning to run the microwave off the inverter?
 
corn18 said:
The BMS determines the discharge rate. So yours is 120A. So you really don't need wire and fuses for 200A. I would still use 2ga wire and a 200A fuse, though. My SOK BMS says it is 100A / battery and I have pulled 115A for 10 minutes from it when I had the microwave and residential refrigerator running at the same time.

120A @ 12V is 1,440W. That should be plenty to operate your 1000W inverter and some other basic DC loads. Are you planning to run the microwave off the inverter?
Click to expand...
i only use my microwave when my generator is on and have no need to connect it to the inverter , i hardly use it

the only ac load that concerns me is the coffee pot and the inverter handles that fine every morning

thanks for the help
 
ok i just dropped $1300 for the following


2 more 200w panels
60a dc-dc charger
250amp high output alternator for the f350
victron 100/50 mppt
and all the wires , fuses , and other misc items needed for install


next up ill try to create a diagram for review ,before i install everything
 
@smoothJoey

why does everyone buy a shunt? i have an app i can use on my phone to monitor the overkill solar bms , is that not sufficient?
 
Zwy said:
I used these https://www.amazon.com/gp/product/B07DN8KMTC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Go heavy, all connections can generate resistance and heat. These are heavy.
Click to expand...
im looking at the link now , but i was asking bc i dont understand where the main positive will lead off , all 4 posts look the same , so it doesnt matter which one i lead to the class t fuse ?

i use the busbar to attach all positive lines , but then what about the line from busbar to the class t or battery? thanks
 
moonlitsouls said:
im looking at the link now , but i was asking bc i dont understand where the main positive will lead off , all 4 posts look the same , so it doesnt matter which one i lead to the class t fuse ?

i use the busbar to attach all positive lines , but then what about the line from busbar to the class t or battery? thanks
Click to expand...
All the posts are the same, so attach main battery line anywhere. And then attach all the loads anywhere. Try not to stack a lot of wire lugs on a single post.
 
moonlitsouls said:
@smoothJoey

why does everyone buy a shunt? i have an app i can use on my phone to monitor the overkill solar bms , is that not sufficient?
Click to expand...
If your BMS does current accounting then the shunt is functionally redundant.
I have the 8s overkill bms and the current accounting loses ~1.6ah per charge cycle.
I also have a cheap hall effect sensor based monitor which resets on each charge cycle and pretty accurate.
Hall effect sensors are not good for mobile applications.

Code: 
2021-09-28 06:58:03 Low=3.390V Average=3.410V High=3.428V Delta=0.038V Balance=01010001 Cell=26.5C Ambient=24.9C SOC=166.2AH Rate=12.0A boost 05:57:57
2021-09-28 06:58:09 Low=3.381V Average=3.399V High=3.417V Delta=0.036V Balance=00000000 Cell=26.5C Ambient=24.9C SOC=166.2AH Rate=0.0A float 00:00:06
--
2021-09-29 06:59:30 Low=3.389V Average=3.410V High=3.427V Delta=0.038V Balance=10100000 Cell=25.8C Ambient=24.3C SOC=164.3AH Rate=11.8A boost 05:59:23
2021-09-29 06:59:36 Low=3.381V Average=3.398V High=3.415V Delta=0.034V Balance=00000000 Cell=25.8C Ambient=24.3C SOC=164.4AH Rate=0.0A float 00:00:06
--
2021-09-30 06:35:03 Low=3.390V Average=3.410V High=3.427V Delta=0.037V Balance=10100000 Cell=26.0C Ambient=24.2C SOC=162.7AH Rate=12.0A boost 05:34:56
2021-09-30 06:35:09 Low=3.381V Average=3.399V High=3.416V Delta=0.035V Balance=00000000 Cell=26.0C Ambient=24.2C SOC=162.7AH Rate=0.0A float 00:00:06
--
2021-10-01 06:44:30 Low=3.390V Average=3.409V High=3.426V Delta=0.036V Balance=10100000 Cell=25.8C Ambient=24.2C SOC=161.1AH Rate=12.0A boost 05:44:24
2021-10-01 06:44:36 Low=3.381V Average=3.399V High=3.416V Delta=0.035V Balance=00000000 Cell=25.8C Ambient=24.2C SOC=161.1AH Rate=0.0A float 00:00:06
--
2021-10-02 06:51:26 Low=3.389V Average=3.410V High=3.427V Delta=0.038V Balance=01010001 Cell=26.2C Ambient=25.1C SOC=159.8AH Rate=12.0A boost 05:51:20
2021-10-02 06:51:32 Low=3.381V Average=3.398V High=3.416V Delta=0.035V Balance=00000000 Cell=26.3C Ambient=25.1C SOC=159.8AH Rate=0.0A float 00:00:06
--
2021-10-03 06:42:33 Low=3.390V Average=3.411V High=3.429V Delta=0.039V Balance=01010001 Cell=27.2C Ambient=25.7C SOC=158.8AH Rate=12.0A boost 05:42:27
2021-10-03 06:42:39 Low=3.382V Average=3.400V High=3.417V Delta=0.035V Balance=00000000 Cell=27.2C Ambient=25.7C SOC=158.8AH Rate=0.0A float 00:00:06
--
2021-10-04 06:32:39 Low=3.389V Average=3.410V High=3.429V Delta=0.040V Balance=10100000 Cell=27.3C Ambient=26.0C SOC=157.0AH Rate=12.0A boost 05:32:33
2021-10-04 06:32:45 Low=3.382V Average=3.399V High=3.418V Delta=0.036V Balance=00000000 Cell=27.3C Ambient=26.0C SOC=157.0AH Rate=0.0A float 00:00:06
--
2021-10-05 06:34:36 Low=3.389V Average=3.410V High=3.428V Delta=0.039V Balance=01010001 Cell=26.7C Ambient=25.3C SOC=155.2AH Rate=12.0A boost 05:34:30
2021-10-05 06:34:42 Low=3.382V Average=3.399V High=3.417V Delta=0.035V Balance=00000000 Cell=26.7C Ambient=25.3C SOC=155.2AH Rate=0.0A float 00:00:06

The 280 ah battery is being charged >95% full each night so as you can see the drift has accumulated to silly proportions.
 
moonlitsouls said:
if i use 2 awg wire from positive bus bar to class t fuse , max amps for 2 guage wire is 205a ,

so ill use a 200amp class t fuse
Click to expand...
Based on the calculations in post #5 you only need a 125A Class T fuse given that you have a 1000W inverter. 200A is the max fuse size for 2AWG but that doesn't mean you need to use the max size fuse. And if you later decided to get a bigger inverter (say 2000W) then neither the 2AWG nor the 200A fuse will be big enough so going with the larger wire and larger fuse gains you nothing. It's fine to use the 2AWG wire if that's what you have but it doesn't really provide any useful upgrade path.
 
moonlitsouls said:
im looking at the link now , but i was asking bc i dont understand where the main positive will lead off , all 4 posts look the same , so it doesnt matter which one i lead to the class t fuse ?

i use the busbar to attach all positive lines , but then what about the line from busbar to the class t or battery? thanks
Click to expand...
Battery cable from ANL fuse can go to any terminal, it just depends on what other circuits you need to run and how you will have to route them.
 
As I stated in post #22, the wire and breaker between the SCC and the bus bar needs to account for the SCC outputting up to 50A to the battery. So that means 6AWG wire and a 65A or 70A breaker.

The shunt for the BMV-712 goes between the battery negative terminal and the negative bus bar.

Your inverter fuse should be 125A, not 110A. 110A would work but if you ever actually put a 1000W load on the inverter you might pop the fuse since it is really close to the max load.

Since your SCC can handle up to 100V input from the panels you should be safe and make sure the breaker you have between the panels and SCC can actually handle that much voltage. Many DC breakers max out at 36V or 48V.
 
moonlitsouls said:
@Zwy @corn18 @rmaddy @smoothJoey

guys , pls take a look and let me know what you think of this?
Click to expand...
Based on my previously stated strategy....
Use 4 awg with 150 amp fuses for all your core connections.
That is...
battery to busbar
busbar to inverter
busbar to dc2dc charger
busbar to scc

I don't see a dc distribution panel or fuse_block, are you not going to have any pure dc loads?
 
Last edited:
rmaddy said:
As I stated in post #22, the wire and breaker between the SCC and the bus bar needs to account for the SCC outputting up to 50A to the battery. So that means 6AWG wire and a 65A or 70A breaker.
Click to expand...
got it , ok i got a 62a breaker that is good for 400 volts , the 16a breaker from the panels to the SCC is also good for 400 volts


rmaddy said:
The shunt for the BMV-712 goes between the battery negative terminal and the negative bus bar.
Click to expand...
copy will add to diagram

rmaddy said:
Your inverter fuse should be 125A, not 110A. 110A would work but if you ever actually put a 1000W load on the inverter you might pop the fuse since it is really close to the max load.
Click to expand...
this is what came with the device so i just checked the manual to see what it was and added it
 
Also suggest to just buy black wire and get some red electrical tape to flag the positive wires.
Also get some green tape for the ground wires.
 
Last edited:
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