Tricky situation

Mike6622

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Im looking to build an off grid system for a new home. Running the home from the grid is not practical because the main power line is about 550ft from the home site. However I was wondering if it would be possible to "trickle charge" a battery bank over night with grid power at that distance. I understand the voltage drop over that distance would be fairly steep but can charge controllers handle the drop?
 

FilterGuy

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Im looking to build an off grid system for a new home. Running the home from the grid is not practical because the main power line is about 550ft from the home site. However I was wondering if it would be possible to "trickle charge" a battery bank over night with grid power at that distance. I understand the voltage drop over that distance would be fairly steep but can charge controllers handle the drop?
That depends on the size wire, the amount of current, the voltage at the grid, and, of course, the charge controller.

Tell us more about the setup you are thinking of.
 

RV10flyer

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Im looking to build an off grid system for a new home. Running the home from the grid is not practical because the main power line is about 550ft from the home site. However I was wondering if it would be possible to "trickle charge" a battery bank over night with grid power at that distance. I understand the voltage drop over that distance would be fairly steep but can charge controllers handle the drop?
I use 30-70kWh per day. I would need at least 15A@240VAC minimum to recharge overnight. I would need 1/0AWG to run 550’. For what I’d spend on conduit, wiring, labor, paying the power co….I’d just put that into more panels.

You should plan on $80K or about double what your greedy power company is charging. It’s worth it to me to have them go pound sand.
 
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400bird

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Anything is possible. I just ran the calc and it looks like you could stay under 3% voltage drop if you run 4 awg at 10 amps. But I didn't even add in the reduction for constant usage. So, 8 amps.

I understand the voltage drop over that distance would be fairly steep but can charge controllers handle the drop?
Charge controllers turn DC into AC, so I'll say probably not.
 

Rednecktek

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If you have your local PUD run it, they'll probably drop a transformer at your end so you can still get 200a of service at the meter.

If you're running it yourself you'll just have to run really thick wire and de-rate your source.
 

John Frum

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What about primary voltage to a pad mounted transformer?
 

Mike6622

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The property has whats left of an 1800s farm house next to the county road. The property is serviced with two power poles. The first power pole on the property has a transformer and the second has the meter and a panel. There is a 150amp breaker in that panel and that power runs from the last pole into the house. The farm house is going to be disconnected from the grid.

I will be building a 1600 square foot home set back in a clearing 550' from the pole where the panel and meter are at. Im considering building with ICF or 2x6 framing (tightly built envelope with lots of insulation). My big power demands will come from a few small mini splits for cooling, a heat pump water heater and ventless dryer. I am heating almost exclusively with a wood stove and I plan to do the same in the new home.

As this is a new build I have zero real world data on the house but I have the ability to explore all available options. I have considered just installing more panels as RV10flyer stated. I had also thought about running a trench from the pole to the house to support a lower amperage "trickle charging" setup for days when the cloud cover is thick.

The expense of having the power company route a line to the house and drop a transformer is in the neighborhood of 40k. At that point I could start making my own power. Thanks for the input, I don't know what I don't know and I appreciate all of the info I can get.
 

OzSolar

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I think a rough formula I would start with would be:

Total Daily Usage x 1.2 / 24

Let's use 30 kWh x 1.2 / 24 = 1.5 kW charging rate

1500 watts/240 (assuming you'd feed to 240 AC to you inverter/charger)= 6.25 amps.

If we round that up to 8 amps for a bit more safety my voltage drop calculator spits out #8 copper or #6 aluminum
 

John Frum

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There is a 150amp breaker in that panel and that power runs from the last pole into the house. The farm house is going to be disconnected from the grid.
Are we to understand that you want to run power from the panel on the pole at the old farm house to the new site, but just use it for charging your battery bank?
 

Mike6622

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Are we to understand that you want to run power from the panel on the pole at the old farm house to the new site, but just use it for charging your battery bank?
That was the idea. I would use the grid power only for charging the batteries at a slow rate over time. The grid power would only be used to supplement power from a solar panel array on cloudy days. I would use an inverter to power the loads for the house.
 

John Frum

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That was the idea. I would use the grid power only for charging the batteries at a slow rate over time. The grid power would only be used to supplement power from a solar panel array on cloudy days. I would use an inverter to power the loads for the house.
This is a voltage drop calculator.
It should help you figure out what size wire is required.
550 feet is 1100 feet round trip.
 
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