My first Off grid solar system

Pre-Inverter Fuse
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I'd recommend what is in the manual. Lack of that, I use an ANL fuse.

The formula for fuse size is:

Low Voltage cutoff X Inverter Wattage X 1.15 = Expected Amps

Expected Amps X 1.25 = Amperage of fuse with headroom

Install a fuse that is "Amperage of fuse with headroom"

For a 1000 watt inverter with a low voltage cutoff of 10.5 this is:

10.5 X 1000 X 1.15 = 109.5 amps

109.5 X 1.25 = 136.9 amps

With that, I'd get a 125 amp fuse, or a 150 amp fuse.

Post-Inverter Fuse
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Check the manual. In my case, there's fuses internally so I do not need a fuse post Inverter.

What voltage and chemistry is your battery? The type of fuse may depend on that. 48 volt Lithium packs can deliver a lot of current on short circuit and Class T fuses are recommended in that situation.

The fuse size should be sized to protect the wire but wire size should be sized to be adequate for the anticipated loads. So start there.

Guys I'm back. Everything I had was sold new before I got chance to test it. I'm planning a new system for off grid farm. Again, main focus is supply power to fridge. Last time I already bought the components and then posted my questions. This time, however, I'll ask first. The biggest change I want to make is using one LITHIUM battery at 300Ah to address the depth of discharge issue. Please let me know if this is wise decision. I saw this battery on Amazon see link below:


So let's review the numbers that some of you helped me with:

Fridge 280KWh/yr = 770Wh/day
Inverter 290Wh/day

Total 1060Wh/day
For all intents and purposes, you guys said go bigger because you always want more.
So I want to consider 1200Wh/day.
300Ah Lithium phosphate battery.
Caribbean weather (close to equator) 10 hr of sunlight but let's consider 7hrs to cater for cloudy spells.
Plenty real estate so panels not roof mounted, instead racked on the ground.
I like the idea of 1 wind turbine (minimum 200W) to make it a hybrid system.
Cheap LCD battery monitor.
40A or 60A MMPT controller? Recommendations?

Can you guys help me design such a system?

Can you recommend any wholesale company (preferably US east coast) that can supply me long term if I get customers.

For a cheap LCD battery monitor, try the Ali battery monitor, about $40 off Amazon, or $20 off Ali Babba. just the bare basics for a shunt, monitoring off a small LED screen and limited programmability. I have one.

Wind turbine is a bad idea, especially for a small one. Short story is they do not last and are a lot more complicated than solar. I recommend going to Fieldlines dot com if you are interested. That is the most dedicated wind forum I found.

I caution you about the fridge consumption, likely to average 770 Wh a day, but would use more in the summer and less in the winter. You do need to plan off something. If your numbers are off too much in the summer, it. Means one more battery and some more panels to charge it.

I recommend you go to a solar calculator like PV watts to see the prodcution by month and decide off data how many panels to get. The size of the MPPT will be based off the voltage.

I’d then take that data and decide the amperage of the SCC. i would consider up to a 100 amp controller, which would replace your daily usage in about an hour if conditions are such that you often have cloudy days, so the battery will quickly recharge in breaks of sunshine. This all depends on if you don’t mind using the grid or turning the generator if the battery is low. For the actual controller, I use Victron and there are a few models that will work. You may find two 50 amp controllers are more cost efficient than a single 100 amp controller.

Really a great job for the first Off grid solar system