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Tell me about your property. Inverter distances, amp ratings, etc

Stewfish

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Oct 20, 2020
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Let me know about your property system and any regrets or how well it's running. We have 10 acres and I'm planning to build a 1600 sq ft house off grid 100%. I'm trying to design my (US) residential side of things of the solar system. I don't want to tax the inverters too much. My knowledge is coming from a normal 240v residential panel w a 600v service. I have built 2 houses, remodeled 1, remodeled a condo in a commercial building, and a townhouse. I'm no electrician, but im many cases I have done all the work and had an electrician just connect it at the main panel. I have installed many sub panels, hot tubs, etc.

Normal 240v vs being limited to 120v configuration:

I know you can run a MPP 2 hot legs into a transformer to get split phase for residential. But MPP says you cant stack the inverters though.

I want to future proof encase I upgrade my inverters one day. From what I can tell I would only be running one 120v conductor/leg to one bar in the house panel. This means no 240v breakers eg 40a or 50a. I wont have any 240v fixtures, so that is okay. Is it best to use a normal 200a panel and just use one side/bar?

30a breaker limit:
I don't think I have ever seen a 120v 50a let alone a 60a single conductor breaker. I was thinking have a panel in a solar shed that feeds the other structures for safety. But if I had a panel in the shed it would be limited to single conductor 30a lines to feed each structure sub panel. To get the rated 60a from the inverter to the house I'm thinking just have a disconnect between the inverter and the house. Have a 2g conductor feed the house panel. Then add a normal 200a $120 panel at the house and only use one side.

Frequently I often see issues with stuff near the house during future projects esp where heavy machinery or vehicles are needed. I'm thinking 75 ft is plenty far enough from the house to future proof. But realistically 25 ft will be far enough.

Voltage drop:
60a at 75ft w/ 4g wire is 1.86% loss = 117.7v
60a at 75ft w/ 2g wire is 1.17% loss =118.5v
60a at 75ft w/ 1g wire is .93% loss =118.8v.
60a at 75ft w/ 1/0g wire is .74% loss = 119.1v
60a at 25ft w/ 2g wire is .39% loss = 119.5v

What is a safe distance /amperage for the inverters to actually handle? Is there a ratio vs grid electric. I bet its lower than residential for the inverters to be safe and not heat up too much. I posted the inverter specs below.

Stacked inverters to a combiner box?
Do I use a combiner box of some sort to get the two 60a conductors down to a single 120a conductor to feed the house? To my understanding I can't do 240v. My plan was to use two off grid MPP all-in-one 3k 48v 60a inverters stacked for the house and another set to power the garage and future mother in-law cabin. I'm thinking 3k so that the second inverter isn't used much and is a backup, but also available so my wife or family doesn't over tax the 1st one and burn up devices. I didn't see 4k 48v inverters on watts247, but I thought MPP made them if so.I'll go with 4k.

I guess I could just get one of these 240v inverters but I'm not sure if it has automatic generator startup.

Welder:
However the only thing I would want a 240v service for is a welder in the garage. It might be good to have everything future proof with 240v. Otherwise I can always use my generator for that and I have built a smoker off the generator/welder. Welding is a lot.of power also that I think I don't want to be drawing off the solar system components for longevity issues. I could be wrong tho. Can I run a second inverter to a second leg/bar to get 220v? Or get the mpp 230v european inverter? I think I remember its expensive and not doable with basic mpp all in one inverters. So that limits me to one leg of 120v. I think the highest 120v breaker I have seen is 30a max.

3k 60 amp inverter - https://watts247.com/product/pip-3048lv-mk/
 

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Too much info for me to digest, so I'll just make a couple observations:

The inverter you linked shows a genny auto start connector.

Consider not entrusting your power needs to cheap units. The higher priced units are the ones you expect a lifetime of trouble free service with good surge capabilities. MPP Solar HF inverters have negligible surge capability. They may say 2X rated for surge, but it's for milliseconds.

Lastly, consider putting your inverter near where you need the power and running your array wires. Many charge controllers are 150V with some up at 250V. There are even some that can handle 600V.

5% drop is required for the National Electric Code, so anything better than that is okay. Lower is better of course.
 
90 acres, 5kw PV xw6048 inverter 800ah 48v NiFe battery
Run 1,000' #2 aluminum wire to deep well pump, feeds 12,000 gal of gravity feed water for property.
All is conventional house wiring, no tricks or shortcuts. Any $15 electrician can make sense of it, and that's the way you want it

2400sf house is 500' from power shed, #4 copper and it's own sub panel.

House is heated with wood masonry heater cooking is propane

hot water is solar thermal & propane tankless

2 backup diesel manual start generators, both 240VAC 3kw each. Either can run all required loads
 
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