Solar system distance limitation best option

cartrydge

New Member
Joined
May 11, 2022
Messages
4
I run a a small solar system on one part of our property with the Delta Max pro system. We are looking at adding another system to our metal garage / shop and use it as a backup generator for our house and also supply offgrid power for our garage for day to day use. I'm trying to figure out the best way to go about this and if the distance is going to be a problem.

Here is what I'm looking at doing to start and then grow as needed.

2 x 6500 watt inverters
4kw in solar panels
9kw in 48v batteries

We currently have a pole barn and metal garage about 130 ft from our house we are building. Ideally I would like to put all the panels on the garage and the metal pole barn instead of our house. Then install the inverters and batteries in the garage. Then we could use the system to provide offgird power to our garage and look at running a power supply line over to our house either plugging into our panel or use it to connect to our 50 amp outside generator plug if and when power goes out. That way we can power a few items like frig and freezers.

My concern is the metal garage may get to warm for the batteries or inverters. It is insulated on the roof but, here in NC it can reach in the low 100s in the summer and also get pretty cold in the winter.

Option 2 would be mount the solar panels then install everything else in our new house like inverters and batteries in the basement and just run a normal sub panel back over to our garage. Again this would be 130 ft to our basement give our take a couple feet.

Any help or ideas would be appreciated.

Thank you
 

chrisski

Solar Boondocker
Joined
Aug 14, 2020
Messages
3,380
I like for long distance runs to have high voltage DC going to the place the batteries are needed the most. There's a huge loss with lower voltages when running higher wattage loads. AC is strictly limited to either 120 or 240, DC can go higher.

There's a lot of different combinations of voltages and wire gauges. The higher voltages with mostly the much less loss for a thinner, easier to run wire and to lesser extent the cost, is what I'm leaning to if I were to do this. If panels are on the garage and it's sent to the house, would look like this:

4500 watts at the source and end for a 130' run can look like:

1) 45 volts and 100 amps
Wire: 2 AWG ($3,17 / foot * 130 feet*2 (one positive one negative)=$824.20)
Loss: 11.62% (3971 ending watts)
1652307667136.png
2) 450 volts and 10 amps
Wire: 12 AWG ($.45 / foot * 130 feet*2 (one positive one negative)=$117)
Loss: 1.16% (4428 Watts)

1652307733439.png
This chart shows wire ampacity which is often the limiting factor for shorter runs with little voltage loss, but also determines the minimum wire size I'd want for a given run.

1652307324484.png
You can always put a transformer on each end to step up and then down the AC for long runs, but those can be expensive, have loss, are anotehr failure point, but might be good in some cases.
 

rmaddy

Full-time Solar-powered Trailer Life
Joined
Nov 16, 2019
Messages
3,384
Location
USA
Try to arrange your solar panels to max out the voltage and minimize the amperage. Then running the 260' round trip with sufficient wire should result in fairly minimal voltage drop. The max voltage depends on your solar charge controller and the minimum temperature you will ever possibly see.
 

cartrydge

New Member
Joined
May 11, 2022
Messages
4
Thank you for all the information. Do you guys think the equipment in the garage would get to hot if I did decide to go that route ? I see the cheapest and best loss solution would be to run the array over and put the equipment in the garage but, then I still need to get some sortt of power in the garage itself.
 

rhino

Solar Addict
Joined
Jun 6, 2020
Messages
754
Location
Minnesota

cartrydge

New Member
Joined
May 11, 2022
Messages
4
I like for long distance runs to have high voltage DC going to the place the batteries are needed the most. There's a huge loss with lower voltages when running higher wattage loads. AC is strictly limited to either 120 or 240, DC can go higher.

There's a lot of different combinations of voltages and wire gauges. The higher voltages with mostly the much less loss for a thinner, easier to run wire and to lesser extent the cost, is what I'm leaning to if I were to do this. If panels are on the garage and it's sent to the house, would look like this:

4500 watts at the source and end for a 130' run can look like:

1) 45 volts and 100 amps
Wire: 2 AWG ($3,17 / foot * 130 feet*2 (one positive one negative)=$824.20)
Loss: 11.62% (3971 ending watts)
View attachment 94325
2) 450 volts and 10 amps
Wire: 12 AWG ($.45 / foot * 130 feet*2 (one positive one negative)=$117)
Loss: 1.16% (4428 Watts)

View attachment 94326
This chart shows wire ampacity which is often the limiting factor for shorter runs with little voltage loss, but also determines the minimum wire size I'd want for a given run.

View attachment 94324
You can always put a transformer on each end to step up and then down the AC for long runs, but those can be expensive, have loss, are anotehr failure point, but might be good in some cases.
How do you keep the amps so low and voltage that high? if you are running say a 365w panel just one panel is around 8amps. if I'm running a series of panels I'm going to be well above 10 amps
 

Lost_One

Solar Enthusiast
Joined
May 13, 2022
Messages
34

chrisski

Solar Boondocker
Joined
Aug 14, 2020
Messages
3,380
How do you keep the amps so low and voltage that high? if you are running say a 365w panel just one panel is around 8amps. if I'm running a series of panels I'm going to be well above 10 amps
With high DC voltage, working with it does make me a bit nervous. There's a reason that house power is delivered with AC and not DC. I've maxed out around 100 volts for some of the stuff I worked on. There's a bit of math to be done for this and Solar controllers more than 150 volts seem hard to get and ones up to 450 VDC get harder.
 
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