Simple system but I need help with it.

[Whats-n-Watts]

Im new too but some things you might consider.

To charge batteries the panels have to produce more than the load. The extra goes to batteries.

The sooner your panels hit charging voltage in low light the better. This might also help you choose between 12or 24V setup.

Battery charge rate and discharge rates need to allow the amperage you plan on utilizing both from panels and to inverter. This include the combined starting surge.

Usage will definitely vary depending on environmental conditions. I have a new 100w fridge that draws 10w per hour on 300+ hours of kilometer monitoring. 10whr right? It climbed up to 80whr on initial startup.

I've conducted an audit for 2 months daily. I know when these run and for how long in 4 hour increments. 700 wh is the most they use during off peak hours. I manipulated them to do that to a degree. I noticed the cycling pattern and simply unplugged them until I got most of the load to be after 10 a.m. at that point the sun has been hitting them for almost 2 hours. The entire wh use per day was 2310 max in summer. A freezer is fine this time of the year unplugged for up to 3 days thawing and at least 1.5 days in the middle of summer. A 300ah battery will have more than enough to provide during a day of low solar. A 600 watt array is sufficient in a perfect world but bare minimum. This will be 1500w total. Over half minimum required for a load of 210 watts with all 3 appliances running so it's a light load that isn't continuous. So hopefully this will cover even a mostly cloudy day. The system has its own panel. Three 15 amp breakers per appliance. Right next to those outlets 2 inches away is a grid outlet. I don't expect it to develop power in extreme cloud conditions but I do expect it to be self sufficient in up to 60 percent. If I don't see that happening more panels it is until I can run it with a candle ?

 

[MisterSandals]

Isn't the charge controller there to regulate and control the amps by the appropriate settings entered? Then those are the amps the battery receives?

900W / 14V = 64A

The 64A is the max current that 900W of panels can provide at 14V. If you have a 40Acharger, it obviously can only deliver 40A. Similarly, some SCCs have settings to restrict charging amps in case your battery cannot accept the max available amps.

Think of the battery as a storage device (like a gas tank) for watt hours (Wh).

12.8V x 300Ah = 3840Wh

Like this. So if you have an inverter and the inverter pulls a 500W load:

3840Wh / 500W = 7.68h runtime.

 

[littleharbor2]

2p3s so amps to battery would be less than 13 amps so 8awg would be over kill. I like over kill lol

You're way overthinking this. Look at it this way, MPPT watts in = watts out. PWM amps in = amps out.

 

[JBoffgrid2022]

200 years ago they would've dug a cave or room into the side of a slope and put ice from the winter in it to keep it cool, covered with sawdust as an insulator...
Why not take away the source of the heat and reduce the amount of power needed to cool? You might end up not needing nearly as much power to do the same task. Just a thought....

 

[Whats-n-Watts]

The 64A is the max current that 900W of panels can provide at 14V. If you have a 40Acharger, it obviously can only deliver 40A. Similarly, some SCCs have settings to restrict charging amps in case your battery cannot accept the max available amps.

Think of the battery as a storage device (like a gas tank) for watt hours (Wh).

Like this. So if you have an inverter and the inverter pulls a 500W load:

3840Wh / 500W = 7.68h runtime.

Yes I'm well versed on battery calculations, ah, watts, wh and all of that. It was the charge controller amp output to battery I wasn't understanding but do see what you're saying. It was just my understanding the settings in thew charge controller determined / limited amps. The 900w array actually calls for a 75A controller but I already had a 100a on hand. And yes a battery holds power I was a mechanic 26 years so I'm not ignorant to how dc systems work by any means or A/C as well.
So I have back ground in both. Solar components full functions I was somewhat ignorant to but already had the mental capacity to understand the basic principles. How it all technically worked together not so much.

 

[Whats-n-Watts]

You're way overthinking this. Look at it this way, MPPT watts in = watts out. PWM amps in = amps out.

I completely get that! Thanks a million