Small system for cabin, first atempt. Advise welcome!

[124C41]

This is my first solar project. I've tried to do my homework the past few weeks and this what I have so far, but I still have a few questions. Let me know if you see any pitfalls here.


This is for a small one room cabin. The intention is to charge phones/laptops, run a 24V DC fan in summer, and interior and exterior lights. (DC, Probably LEDs)
I have two 230W hyundai solar panels that I intend to wire in parallel to a Xantrex C-60 PWM controller to charge two 12V 200ah AGM batteries wired in series. I'm planning on using 6 AWG wire, I'm guessing about 20 foot from the panels to the controller then another 4 foot to the batteries. The C-60 has an optional battery temp sensor.


Is this something you would feel comfortable leaving unattended for several weeks? Should there be some sort of cooling fan on the controller or batteries for 90° summer days?

Surely there needs to be a fuse or two in here some where, would 60 AMP be appropriate between the PV and controller and between controller and battery?


Thanks!
JB

[Mike90250]

Yes, you should have a 20 - 25A between the Battery and the Charge controller . Just one fuse on the + wire is enough. 2 panels in parallel do not need a fuse.
for longest battery life, you should use a BTS made for the C-60, and disable the automatic EQ cycle . You should monitor the specific gravity to decide when to EQ the batteries.

While away, all loads should be disconnected , but the charger should remain connected, to prevent self-discharge of the batteries, and the shortened life caused by low voltage levels.
You have a quality charger C-60, and it should be fine to leave it tending the batteries.

[124C41]

Yes, you should have a 20 - 25A between the Battery and the Charge controller . Just one fuse on the + wire is enough. 2 panels in parallel do not need a fuse.
for longest battery life, you should use a BTS made for the C-60, and disable the automatic EQ cycle . You should monitor the specific gravity to decide when to EQ the batteries.

While away, all loads should be disconnected , but the charger should remain connected, to prevent self-discharge of the batteries, and the shortened life caused by low voltage levels.
You have a quality charger C-60, and it should be fine to leave it tending the batteries.

What did you use to decide fuse A?

[donald]

Is this something you would feel comfortable leaving unattended for several weeks? Should there be some sort of cooling fan on the controller or batteries for 90° summer days?


JB

Your batteries will be floating most of the time, so not much heat will be generated. You will probably just want to open the compartment when you leave. Have you calculated the charge rate from your panels?

[124C41]

Your batteries will be floating most of the time, so not much heat will be generated. You will probably just want to open the compartment when you leave. Have you calculated the charge rate from your panels?

I have not!

[124C41]

So if I'm doing the math right. The two panels Imp : 15.8 , so charge rate would be C/12.6 ?

[mschulz]

So if I'm doing the math right. The two panels Imp : 15.8 , so charge rate would be C/12.6 ?

The math is:

Charge rate from your panels = Battery Bank Amps / Charging amps to Battery
Charging amps to Battery = Total PV Watts / System Voltage

Your System:

460W/24V= 19.16
200AMP / 19.16 = C/10.43

[Wy_White_Wolf]

The math is:

Charge rate from your panels = Battery Bank Amps / Charging amps to Battery
Charging amps to Battery = Total PV Watts / System Voltage

Your System:

460W/24V= 19.16
200AMP / 19.16 = C/10.43

He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

WWW

[mschulz]

He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

WWW

Ah, I didn't see that. My Bad.

[124C41]

He's using a PWM charge controller so he has the calculation right using the IMP of the panels. Your way is using an MPPT controller.

WWW

Dang, I liked his math better. I'm guessing a MPPT would be that much more efficient?

I picked up the PWM controller a couple of hours ago and 80FT of 6 AWG wire. (Wire is expensive...)
The 20 Amp fuses / holders I have been looking at all seem puny and would be hard to attach to the 6 AWG. Does anyone have a suggestion on the style of fuse and size of wire between the controller and batteries? Or maybe a breaker.

Thanks for your responses BTW.