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Hello all. I am new to this forum.
Just a little about my background - I have a basic background in electricity and have a general knowledge of solar, how it works, and how it should be setup as a power source (probably just enough knowledge of both to be dangerous...).
My company manages a mobile mammography/cancer screening unit for a local hospital. Due to an upgrade in x-ray equipment, they had to completely upgrade the power source on the truck with larger equipment. The equipment that was removed was given to me.
I have -
2 - Xantrex Freedom SW 815-3012 inverter/chargers (3 years old)
2 - Xantrex TrueCharge2 Series 60amp battery chargers (3 years old)
4 - 8275 series 12 volt GEL Batteries that have a 20 Hr. rate /225Ah (13 months old)
I also have the remote panels that operate the devices.
This equipment was configured in a "stacking" setup on the truck. I have spoken with the tech folks at Xantrex and they say that they will be happy to walk me through "unstacking" this equipment so it can be used independently.
I have an off-grid cabin (no power currently) in southern KY that I would love to have power in.
From what I've learned, 12 volt is better suited to mobile, RV and marine. Higher voltage setups are much preferred for things like cabins. I also understand that the voltage is not the dangerous part in what I'm considering. The danger is in the amperage...
With that said, I considered selling these inverters and chargers and using the proceeds to by a higher voltage system. I gave eBay and Craigslist a shot but no luck. I got a couple of crazy low offers but nothing I wanted to consider.
So here I am researching the viability of installing this 12 volt system in my cabin...
Based on different online calculators I have experimented with, when we use the cabin, we need about 2200wh. That's probably a bit high but, I prefer to be conservative rather than disappointed.
The place is small place and we only use it a couple of days at a time here and there throughout the year. To take advantage of the 12v, I can use a lot of RV type of accessories that are readily available (lighting, fans, etc.). Including an RV fridge that can run on propane, 12v, or 120v AC that I already have.
By using a 1.5 "fudge factor", I come up with 3300whs.
Here is where I think I'm going at this point. Maybe one of you good folks can redirect me if necessary...
Inverter - Use the one of the 12 volt Xantrex 3012 inverters that I have to convert the DC for AC loads. 3000 watts is overkill I'm sure...
Storage - My calculations tell me I need 1375Ahs for storage. I'm short here. As I indicated above, I have four 12v 225ah GEL batteries. I'm thinking of setting up two parallel 12v battery banks. That gives me 900Ahs total storage.
When I'm at the cabin for several days in cloudy weather, I can always fire up a small generator and top everything off. Because we rarely use this place for more than 2 or 3 days at a time, as long as I don't deplete the batteries less than 50% (I'll probably try and keep it to 70%), the solar system can charge for days, if not weeks after we have left there...
For AC charging - The Xantrex 3012 inverter has a built in battery charger. It senses AC power and will switch from inverter mode to charging mode automatically. It has 3 stage charging.
For solar charging - The calculators tell me I need 917 watts of solar panels. I'm thinking of using three 300-watt panels wired in series. As I understand it, the solar panels come with cables (maybe 12 gauge) that have MC4 connectors. I also believe I can get MC4 extension cables (maybe 10 gauge) to run the 15' distance from the panels to the charge controller.
The calculators also tell me I need a charge controller that can handle 75 amps. The Midnite Classic 150 SL MPPT is the direction I'm leaning. That looks to be a quality product with good reviews and gives me room for upgrading my system to 24v or 48v at some point down the road. This has a 96 amp rating so I can add on more solar panels if I want.
Wire size - (THIS IS AN AREA IN WHICH I'M STRUGGLING) I don't have confidence in my level of comprehension of the higher amperage produced by using 12v to determine the appropriate fuse/breaker sizing and wire sizing.
From the charge controller to the batteries will only be about 3 feet or less. I'm planning to mount the CC on the outside wall of the battery box. But, I don't know what the factors are to determine that wire size. Is it 96 amps? That is what the charge controller I'm considering is rated for. If so, use 4ga wire? I guess the terminals on the controller are big enough??
The cables that are currently used to interconnect the batteries are big. I believe they are 2 gauge.
From the inverter to a small AC load center, I'll run some 10ga wire and put that on a 30 amp breaker to feed AC loads to the cabin.
I have attached an illustration/wiring diagram that illustrates what I'm thinking and highlights a couple of areas of concern I have... I am aware that all the devices need an earth ground that is completely independent from the DC negative and AC neutral. I did not show it on this illustration because it really cluttered things up.
I also have concern with this place being remote and not used daily in the winter, there is no way to keep those batteries in a climate controlled environment. My understanding is that batteries in freezing weather is not good for them... They were in a non-climate-controlled compartment on the truck... Is that a serious concern? I know cold affects their performance, but my concern is more long-term damage.
My guess is that there are a multitude things in the scenario above that are either incorrect or that even could be done differently. But this is my jumping off point to see where I need to go...
To summarize what I'm considering (so you don't have to go back and reread everything...) -
Thank you in advance to anyone that is taking their time to read through this and give input. It is much appreciated!!!
Steve
WIRING DIAGRAM.pdf
Just a little about my background - I have a basic background in electricity and have a general knowledge of solar, how it works, and how it should be setup as a power source (probably just enough knowledge of both to be dangerous...).
My company manages a mobile mammography/cancer screening unit for a local hospital. Due to an upgrade in x-ray equipment, they had to completely upgrade the power source on the truck with larger equipment. The equipment that was removed was given to me.
I have -
2 - Xantrex Freedom SW 815-3012 inverter/chargers (3 years old)
2 - Xantrex TrueCharge2 Series 60amp battery chargers (3 years old)
4 - 8275 series 12 volt GEL Batteries that have a 20 Hr. rate /225Ah (13 months old)
I also have the remote panels that operate the devices.
This equipment was configured in a "stacking" setup on the truck. I have spoken with the tech folks at Xantrex and they say that they will be happy to walk me through "unstacking" this equipment so it can be used independently.
I have an off-grid cabin (no power currently) in southern KY that I would love to have power in.
From what I've learned, 12 volt is better suited to mobile, RV and marine. Higher voltage setups are much preferred for things like cabins. I also understand that the voltage is not the dangerous part in what I'm considering. The danger is in the amperage...
With that said, I considered selling these inverters and chargers and using the proceeds to by a higher voltage system. I gave eBay and Craigslist a shot but no luck. I got a couple of crazy low offers but nothing I wanted to consider.
So here I am researching the viability of installing this 12 volt system in my cabin...
Based on different online calculators I have experimented with, when we use the cabin, we need about 2200wh. That's probably a bit high but, I prefer to be conservative rather than disappointed.
The place is small place and we only use it a couple of days at a time here and there throughout the year. To take advantage of the 12v, I can use a lot of RV type of accessories that are readily available (lighting, fans, etc.). Including an RV fridge that can run on propane, 12v, or 120v AC that I already have.
By using a 1.5 "fudge factor", I come up with 3300whs.
Here is where I think I'm going at this point. Maybe one of you good folks can redirect me if necessary...
Inverter - Use the one of the 12 volt Xantrex 3012 inverters that I have to convert the DC for AC loads. 3000 watts is overkill I'm sure...
Storage - My calculations tell me I need 1375Ahs for storage. I'm short here. As I indicated above, I have four 12v 225ah GEL batteries. I'm thinking of setting up two parallel 12v battery banks. That gives me 900Ahs total storage.
When I'm at the cabin for several days in cloudy weather, I can always fire up a small generator and top everything off. Because we rarely use this place for more than 2 or 3 days at a time, as long as I don't deplete the batteries less than 50% (I'll probably try and keep it to 70%), the solar system can charge for days, if not weeks after we have left there...
For AC charging - The Xantrex 3012 inverter has a built in battery charger. It senses AC power and will switch from inverter mode to charging mode automatically. It has 3 stage charging.
For solar charging - The calculators tell me I need 917 watts of solar panels. I'm thinking of using three 300-watt panels wired in series. As I understand it, the solar panels come with cables (maybe 12 gauge) that have MC4 connectors. I also believe I can get MC4 extension cables (maybe 10 gauge) to run the 15' distance from the panels to the charge controller.
The calculators also tell me I need a charge controller that can handle 75 amps. The Midnite Classic 150 SL MPPT is the direction I'm leaning. That looks to be a quality product with good reviews and gives me room for upgrading my system to 24v or 48v at some point down the road. This has a 96 amp rating so I can add on more solar panels if I want.
Wire size - (THIS IS AN AREA IN WHICH I'M STRUGGLING) I don't have confidence in my level of comprehension of the higher amperage produced by using 12v to determine the appropriate fuse/breaker sizing and wire sizing.
From the charge controller to the batteries will only be about 3 feet or less. I'm planning to mount the CC on the outside wall of the battery box. But, I don't know what the factors are to determine that wire size. Is it 96 amps? That is what the charge controller I'm considering is rated for. If so, use 4ga wire? I guess the terminals on the controller are big enough??
The cables that are currently used to interconnect the batteries are big. I believe they are 2 gauge.
From the inverter to a small AC load center, I'll run some 10ga wire and put that on a 30 amp breaker to feed AC loads to the cabin.
I have attached an illustration/wiring diagram that illustrates what I'm thinking and highlights a couple of areas of concern I have... I am aware that all the devices need an earth ground that is completely independent from the DC negative and AC neutral. I did not show it on this illustration because it really cluttered things up.
I also have concern with this place being remote and not used daily in the winter, there is no way to keep those batteries in a climate controlled environment. My understanding is that batteries in freezing weather is not good for them... They were in a non-climate-controlled compartment on the truck... Is that a serious concern? I know cold affects their performance, but my concern is more long-term damage.
My guess is that there are a multitude things in the scenario above that are either incorrect or that even could be done differently. But this is my jumping off point to see where I need to go...
To summarize what I'm considering (so you don't have to go back and reread everything...) -
- 3 - 300-volt panels in series for 900watts.
- A Midnite Classic 150 SL 96 amp MPPT (I need a CC to handle 75amps) --- what should the wire size be for a the 3' run from the CC to the battery bank? What sort of protection should this have? A breaker? Fuse?
- 4 - 12v 225ah GEL batteries. Setup in two parallel 12v battery banks. 900Ahs of total storage. (calculated storage was 1375Ahs. I'm shy of what is calculated but I don't live here. So, I feel it's manageable).
- 1 - Xantrex 3012 3000 watt inverter --- what sort of fuse protection should I have between batteries and the inverter?
- Non-climate controlled battery environment. Is this a problem?
Thank you in advance to anyone that is taking their time to read through this and give input. It is much appreciated!!!
Steve
WIRING DIAGRAM.pdf
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