New to solar. Help with 24V design.

Started by TheChrisP1, March 27, 2021, 04:01:42 PM

Previous topic - Next topic

TheChrisP1

First off thanks for reading and trying to help!

I'm new to solar and trying to learn everything I can. I plan to build a 24V system as a emergency backup (later to be moved to the boat).

Currently I have a MidNite KID (I bought the kit), (2) 195W solar panels and a 3000W Pure Sine Wave inverter. I have a couple of bus bars, 12 Circ. fuse box, a DC to DC converter (24v to 12v) and the breakers sent with the kit.

1. Do I need anything else?
2. How can I determine the correct breakers and fuses to protect my system?
3. Is there a good source of diagrams?

Thank you very much!

ClassicCrazy

The Kid Manual has some good diagrams for panel wiring.
And there is Midnite string sizing tool online that you can plug the specs for your panels into and it will calculate voltage and current levels .
AltE has some good beginners videos on youtube.

The things to consider when wiring up the system is that you use the right breaker or fuse for the wire size.
There are online wire loss calculators so that you know if you are going far with wire what gauge you will need to use so you don't loose power in the wire.
You can use a smaller breaker than wire rating but you can't use a larger one.
For example  - if you were using 12 gauge wire the maximum breaker would be 20 amps. But you could also use a 15 amp if you wanted to ( if  your power was less than 15 amps) .

I think the Kid has 40 amp fuses in it so minimum wire size to and from it would be 10 gauge but you could use larger wire for less voltage drop.

You didn't mention batteries - that is a whole different subject on how to best arrange and use those but depends on battery type.

You will need very large gauge wire and breaker between your batteries and inverter.  You inverter manual should make some recommendations for proper breaker and wire sizes to use.

The thing that I like using for wiring systems is Midnite MNDC box . It has the big breaker for inverter, and has places you can put up to 5 smaller din rail breakers - so one would be for PV input  to controller, one for controller to battery , and then you have three others left  so you can use one to feed your 24v to 12v converter.   The MNDC box also has a place to mount a shunt - which you probably want to use if you are using Whizbang with your Kid to show SOC state of charge. If you don't have the Whizbang and shunt yet I recommend getting those for the useful info you get from them - well worth it.  The MNDC box has a wiring diagram in it - it makes is much easier to wire a system and is nice and neat compared to doing it other ways.

Not sure what kit you got and what is included for breakers.

Larry

system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

TheChrisP1

Thank you for the info. I bought the Basic KID kit. I have a shunt, a Whizbang Jr., 3000w inverter, converter, buss bars, 2AWG wite, 12AWG wire, fuse block, (2) 195w panels, and all the stuff that came in the kit.
I plan to mount everything on a board to give me the option to move it. I haven't bought the batteries yet. Still trying to decide on which ones to get.

ClassicCrazy

good idea on mounting it all on wood - easy to move or rearrange stuff.
I always mount mine on piece of thick plywood.

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable