This is what I have and thinking of buying for my off grid cabin, I would like some input on components if they are good quality.

Tat2rtist

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First off I already have 4 Lifeline 6v 300 AH Deep Cycle Sealed AGM Battery GPL-6CT, I want to hook them up in series for a 24 volt system. I am looking at :

COTEK 3000 Watt 24V Pure Sine Inverter SP3000-124

Victron SmartSolar MPPT 100 / 50A Solar Charge Controller

2 Solar panels
Manufacturer: Q-Cells
Model: Q. Plus Duo L-G5.2 360
Nominal Power: 360 W
Short Circuit Current (ISC): 9.87 A
Open Circuit Voltage (VOC): 46.8 V
Current at Max Power: 9.35 A
Voltage at Max Power: 38.52 V
Frame: Anodized Aluminum Alloy Weight: 23.5kg / 51.8 lbs
Dimensions: 72” x 36” x 1.37”


I understand I will need fuse, shut off between inverter and batteries, wondering on wire size for batteries and to run to inverter.
Any addition input would be greatly appreciated. Also, I will have a generator on this panel, the panel has the neutral and ground bonded, was wondering if anyone knows if this inverter is compatable with a box that has neutral and ground bonded, it is off grid, ( I bonded neutral and ground in the box because my generator is an inverter with a floating neutral, and if it isnt bonded ground faults wouldnt be operable in the cabin, so I have read.). If it isnt compatable with a bonded panel, does anyone know of one that is? If not I will put in a separate ground bar and separate my neutral and grounds. Thanks in advance for any input.
 

Tat2rtist

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Any recommendation as far as equipment or number of panels would be appreciated. I will be running a full size refridgerator and a microwave that is 800 watts, I will have about 150 watts for lighting, and maybe 100 watts for TV, of course not everything will be running at the same time. that is about all that will be run on this system. Not sure if One panel would be enough or if I should get 2, I am located in a slightly wooded area so I figured maybe 2 360 watt panels in case I didnt get enough sun exposure with one panel.
 

Hedges

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Mar 28, 2020
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Not a lot of panels, but then, not a large battery bank.
6 x 300 x 4 = 7200 Wh
Probably wants to be charged 0.1C, maybe 0.2C, so 720 to 1440 W or so of panels. You have 720W STC.
Does that model charge controller know what that model inverter is doing, so you could have much more panels but limit maximum charge current?

I'm not sure which DC coupled systems let you have a large array but control charging current. My AC coupled system (grid-tie inverters and a battery inverter/charger) lets me get away with panels capable of 4C relative to battery. I run most loads directly off PV generated AC during power failure.

How many watts are the loads you plan to run, what kind of surge current to start motors, how many watt-hours do you plan to drain at night? During cloudy/smoky weather?

OK, saw your equipment post.
Refrigerators draw 500 kWh/year, more or less (look up energy label) so 1500 Wh/day assuming comfortable temperatures. 50W average throughout the day, 200W operating, defrost or ice maker could be 800W. Start-up surge 1 kW.

800W cooking power microwave draws about 1500W. How many minutes operation?

With good sun, typical latitudes give 5.5 hours effective sun x panel STC rating x 0.8 for STC x 0.95 for inverter efficiency. Round trip through battery loses more. Batteries cost way more than PV, so trick is to run loads while the sun shines, conserve power at night.

AGM batteries may last 5000 cycles, 15 years of nightly discharging just 10% of capacity, or 500 cycles 18 months of 70% discharge. Check specs for yours.
 

Hedges

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What is your budget?
$200? $2000, $20,000?
You can hit any of those price points, obviously with different performance.

What do you do for water?
 

Tat2rtist

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Water is gravity fed spring. This is a cabin we will be using part time right now, thinking maybe it will be a summer home in 5 years, so the equipment above would be where I would be starting and expanding later if needed. I have generators to help with charging batteries if needed, and also to run bigger loads if needed. Also operating temps might be a problem, this is an off grid cabin, and winters get pretty cold, sometimes 20 to 30 below, cabin is heated with wood, and there will be a lot of days that it wont be heated in the winter. I see the inverter has an operating temp of -20 C which is 4 F. I was wondering how critical this is, I can use extra insulation where everything will be set up, will be like a closet on second floor of cabin.
 

Hedges

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Batteries have varying tolerance to cold, different rules for storage vs. charging in some cases.
Earth, if you get deep enough, is supposed to be a balmy 50 degrees.
Maybe you take the batteries home with you.
Or no batteries, to speak of? You may be able to find a hybrid inverter that does PV direct to AC, with possibly a small battery for surge current.
But in that case you need lots of PV, like 2400W, which would be a target for theft.

How much gravity? (or rather, how much head, how much flow?) Small Pelton wheel turbine could go a long way.
 
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