Because of my location in the winter, the best location for my panels is approximately 350ft away from my house. I will gain 2 more hours of sunlight per day at this distance. Is this possible, and what wire size would I need to run between my panels and the charge controller?
How many feet of wire for a 48v solar system? Is 350ft too far? What gauge of wire would work?
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Bud Martin
Solar Wizard
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The wire size will depend on the Vdrops that you will accept, typical is about 3%.
How many panels and how are the wiring arrangement, spec of the panels and the SCC? We need more info.
How many panels and how are the wiring arrangement, spec of the panels and the SCC? We need more info.
Hedges
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Have you selected anything yet?
There is hardware that runs as high as 600Voc. Typical Vmp might be 380VDC.
It is OK to go well over 3% power loss in PV wire (at maximum current.)
It is just a trade-off between cost of copper (or aluminum, worth considering for such a long run) and silicon.
Multiple array orientations will reduce peak current, give more hours. Power lost in wires goes as current squared, so that is a net win.
There is hardware that runs as high as 600Voc. Typical Vmp might be 380VDC.
It is OK to go well over 3% power loss in PV wire (at maximum current.)
It is just a trade-off between cost of copper (or aluminum, worth considering for such a long run) and silicon.
Multiple array orientations will reduce peak current, give more hours. Power lost in wires goes as current squared, so that is a net win.
Joe BoyKey
Watts, Watts, more Watts
Voltage Drop Calculator
This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.
www.calculator.net
curiouscarbon
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if the battery is 48V and charger is MPPT then solar voltage input should be 48V+5V for smooth charging.
-> 53V and up
as mentioned, building the solar panels so that a higher voltage is going on the long 350ft run will increase the amount of power usable (reduce cable loss)
be careful working around high voltage solar panel connections during daytime, that’s something i’m inexperienced at doing.
blows my mind to think of 5000W flowing over 13A with 380V solar input. i think i’m getting goosebumps from the air molecules aligning to the electric field…
good luck!
-> 53V and up
as mentioned, building the solar panels so that a higher voltage is going on the long 350ft run will increase the amount of power usable (reduce cable loss)
be careful working around high voltage solar panel connections during daytime, that’s something i’m inexperienced at doing.
blows my mind to think of 5000W flowing over 13A with 380V solar input. i think i’m getting goosebumps from the air molecules aligning to the electric field…
good luck!
curiouscarbon
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may i ask, how many Watts of solar panels to place 350 feet away?
curiouscarbon
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this one said 4% drop for 350ft of 10awg copper passing 3A of currentVoltage Drop Calculator
This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.
3A could give 1000W with 330VDC?
330V / 20V per panel -> 17 panels in series?
i have always stayed below 100VDC for my DIY solar builds because ?
️? lack of high voltage safety awareness but here it seems beneficial maybeperhaps something like 100-200V photovoltaic input could work?
Hedges
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That's what I get from 24x 12V panels, 12x 24V panels, 8x 36V panels.
Except, each PV string is between 5A and 8A, not 13A. Most are run up to 150' in 12 awg, but two strings parallel into 8 awg (plan for 3 in parallel, about 21A)
this one said 4% drop for 350ft of 10awg copper passing 3A of current
3A could give 1000W with 330VDC?
330V / 20V per panel -> 17 panels in series?
i have always stayed below 100VDC for my DIY solar builds because ?
perhaps something like 100-200V photovoltaic input could work?
So run 13A in 10 awg for 16% drop.
Hmm, my math comes up different. I tried meters not feed in your calculator, still didn't match your numbers.
10 awg, 1 ohm per 1000', 350' each way is 0.7 ohms round trip. At 13A, 9.1V drop or 2.4%
Table of equivalent AWG Wire and Resistance per foot
AWG Chart of Approximate equivalent Cross-Sections of Wire, American Wire Gauge by Resistance per 1000 feet
www.interfacebus.com
1000' of 10 awg is $1450 ??
Southwire 1000 ft. 4 Black Stranded CU SIMpull THHN Wire 20499004 - The Home Depot
Southwire's THHN and THWN-2 is a multi-purpose building wire used in conduit and cable trays for service, feeders and branch circuits in commercial and industrial applications. It is also used as a conductor
www.homedepot.com
Here's something much more reasonable.
1000' of 12 awg for $183
12 awg, 1.6 ohms/1000 feet, 13A gives 14.6V drop or 3.8% of 380V
13A x 1.56 = 20.28 ampacity required (If rounded down to 20A, 12 awg is rated for that. OK for just under 13A design)
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SignatureSolar.com: Solar Panels, DIY Off-Grid Solar, Server Rack Battery for Solar, Solar Inverters
Signature Solar provides solar panels & components and full kits for off-grid, grid-tie and custom diy solar systems. Providing Solar 101 and hands on experience within the solar industry. Quality inverters, bifacial solar panels, complete solar kits, solar batteries. Holding best in class...
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I found 6 awg 500ft for 369$ at lowes today. 8 awg was somewhere in the mid $200 range for 500ft.That's what I get from 24x 12V panels, 12x 24V panels, 8x 36V panels.
Except, each PV string is between 5A and 8A, not 13A. Most are run up to 150' in 12 awg, but two strings parallel into 8 awg (plan for 3 in parallel, about 21A)
So run 13A in 10 awg for 16% drop.
Hmm, my math comes up different. I tried meters not feed in your calculator, still didn't match your numbers.
10 awg, 1 ohm per 1000', 350' each way is 0.7 ohms round trip. At 13A, 9.1V drop or 2.4%
Table of equivalent AWG Wire and Resistance per foot
AWG Chart of Approximate equivalent Cross-Sections of Wire, American Wire Gauge by Resistance per 1000 feetwww.interfacebus.com
1000' of 10 awg is $1450 ??
Southwire 1000 ft. 4 Black Stranded CU SIMpull THHN Wire 20499004 - The Home Depot
Southwire's THHN and THWN-2 is a multi-purpose building wire used in conduit and cable trays for service, feeders and branch circuits in commercial and industrial applications. It is also used as a conductorwww.homedepot.com
Here's something much more reasonable.
1000' of 12 awg for $183
12 awg, 1.6 ohms/1000 feet, 13A gives 14.6V drop or 3.8% of 380V
13A x 1.56 = 20.28 ampacity required (If rounded down to 20A, 12 awg is rated for that. OK for just under 13A design)
I'm thinking 12 to 16 panels at 395 watt capacity, see the links in my above post.
I put up some more info, let me know what you think.
Actually go up to 8 awg and 10 awg for those prices.
curiouscarbon
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395W version
STC
Max 395 W
Vmp 40.73 V
Imp 9.70 A
Voc 49.03 V
Isc 10.31 A
NOCT
Pmax 294.88 W
Vmp 38.00 V
Imp 7.76 A
Voc 45.80 V
Isc 8.22
Temperature Coefficient of
Voc -0.3%/C
Isc +0.06%/C
STC 25 deg C
NOCT 43 deg C
Last edited:
MichaelK
Solar Wizard
Let's say you wire 10 standard 250W grid-tie panels in series at your designated location. Here's the voltage drop for 10 gauge wire running at 300VDC. I used this voltage drop calculator. https://www.calculator.net/voltage-drop-calculator.html
With 10 panels in series, you are getting less than 2% loss. With only 8 panels in series, it's still less than 3% loss. What you can do with the calculator is play with the parameters and see what you get.
You may find it's more cost-effective to just add a panel or two to a series string, rather than purchasing thicker, more expensive wire. With a 450Voc limit, you have lots of flexibility. Just make sure you account for your winter's lowest temperature. https://www.midnitesolar.com/sizingTool/index.php Midnight's string calculator predicts that this ten panel string will reach 450Voc at about 30 degreesF below zero. You may be happy with just a string of 8 or nine panels.
Utilizing an eight panel string of the panels you mention above, you'll reach 450Voc at about zero F. What are your winter lows like?
With 10 panels in series, you are getting less than 2% loss. With only 8 panels in series, it's still less than 3% loss. What you can do with the calculator is play with the parameters and see what you get.
You may find it's more cost-effective to just add a panel or two to a series string, rather than purchasing thicker, more expensive wire. With a 450Voc limit, you have lots of flexibility. Just make sure you account for your winter's lowest temperature. https://www.midnitesolar.com/sizingTool/index.php Midnight's string calculator predicts that this ten panel string will reach 450Voc at about 30 degreesF below zero. You may be happy with just a string of 8 or nine panels.
Utilizing an eight panel string of the panels you mention above, you'll reach 450Voc at about zero F. What are your winter lows like?
Last edited:
MichaelK
Solar Wizard
BTW, this is very much not correct. The incoming solar voltage needs to be significantly higher than just 5V above 48. The MPPT function needs "headroom" to transform the voltage, normally stated as being at least 30% greater than the system voltage. My own 48V battery is still charging at 59-60V, so 53V would be totally inadequate.
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