220V cable at 200 Feet

[Leemaisel]

I’m building the power shed with batteries and inverters down at the panel arrays, and want to push the 220v to the house from there rather than trying to push the DC from the panels that distance. Looking at around 200’. I’m using a pair of EG4 6.5kW (6500EX-48) bonded together for 220.

What gauge/type cable is recommended to carry the 220vAC the 200’ to the main panel at the house?

Thanks!

 

[SeaGal]

This should help you do the calculations...

Electricity losses online calculator : AC and DC electrical wire voltage drop and energy losses

Quick online free voltage drop calculator and energy losses calculation, formula of electrical DC and AC power wire voltage drop for various cross section cables, power factor, lenght, line, three-phase, single phase. Formula to calculate voltage drop and energy losses.

photovoltaic-software.com

 

[hwy17]

It's easier to run panel DC over long distances since it is not adversely affected by voltage drop except for the watts lost. And since you can run panels at 300v+ then you can use smaller wire, only 10 or 12 awg pairs per string of panels.

 

[Leemaisel]

So unless I’m wrong, and probably am, it calls for #3 THHN

It's easier to run panel DC over long distances since it is not adversely affected by voltage drop except for the watts lost. And since you can run panels at 300v+ then you can use smaller wire, only 10 or 12 awg pairs per string of panels.

As I understand it, DV losses are always greater than AC losses. This is why our power grid is AC(Tesla) vs DC(Edison) am I missing something? I imagine running DC from the panels 200’ would incur more loss at DC than having the powerhouse at the panels, and sending it via AC

 

[740GLE]

Where are you coming up with DC losses are greater?

Voltage is your friend in efficiency.

Take a look at major transmission lines that at 1000 miles long, think of connecting islands to main land and major hubs together, guess if they are DC or AC ?

So back in the day and still applicable, the reason AC “is better” is it’s easier to change voltage with an xfrmr with zero moving parts. Again higher voltage means more efficient.

Back in the day the only way you could easily convert DC from low voltage to high voltage (and vice versa) is via DC motor coupling, which means moving parts (maintenance is always bad on moving parts).

 

[Supervstech]

So unless I’m wrong, and probably am, it calls for #3 THHN

As I understand it, DV losses are always greater than AC losses. This is why our power grid is AC(Tesla) vs DC(Edison) am I missing something? I imagine running DC from the panels 200’ would incur more loss at DC than having the powerhouse at the panels, and sending it via AC

Nope.
Ac is used because transformers were the best way to reduce voltage at homes.
Dc in the past was difficult to send at high voltage and lower at homes.

 

[Supervstech]

Voltage losses dont care ac or dc, in fact HIGH voltage ac has instabilities over long distances not incurred with dc, but tech didnt exist previously to rectify.

For home use, sending high voltage dc to the controller and batteries is usually the best most efficient way to send energy.

 

[Leemaisel]

Thanks for the explanation!

I’m using TEN (to start) Canadian Solar 400w BiFacial panels, which are 38.7v, so only 387v in series.

What Gauge cable would be optimal for the now only two conductors carrying the 387vDC 200 feet?

Eventually I will add more panels, probably series/parallel, so it would still only be 387v, and I suppose it’s only going to be 10A or so?

 

[SeaGal]

There you go.... losses will be much less at 387V than 220V

 

[Leemaisel]

There you go.... losses will be much less at 387V than 220V

Even at only 10A? When putting the 10 panels in series, I’m increasing the voltage, but the amps remain the same, correct?

 

[timselectric]

Let the highest voltage travel the greatest distance. For the most efficiency and least losses. In most cases, this is the PV voltage.

 

[timselectric]

Even at only 10A? When putting the 10 panels in series, I’m increasing the voltage, but the amps remain the same, correct?

Because it's only 10a.

 

[Leemaisel]

What gauge of cable is required for carrying the 387v from the panels 200’?

 

[handinpalm]

So unless I’m wrong, and probably am, it calls for #3 THHN

As I understand it, DV losses are always greater than AC losses. This is why our power grid is AC(Tesla) vs DC(Edison) am I missing something? I imagine running DC from the panels 200’ would incur more loss at DC than having the powerhouse at the panels, and sending it via AC

The only thing you have to worry about is your current and wire resistance. Power loss in your wires/cabling is Current (squared) X resistance. The higher the voltage means you can have lower current. You should always try to keep your transmission line at a high voltage (solar panel output), unless you want to keep all your equipment far away (in shed) for fire/insurance reason.

 

[timselectric]

Higher voltage means lower amperage. Lower amperage means lower losses.

 

[timselectric]

What gauge of cable is required for carrying the 387v from the panels 200’?

387v at 10a for 200' requires #12 gauge copper.
Voltage drop will be 1.93%.

 

[SeaGal]

What gauge of cable is required for carrying the 387v from the panels 200’?

Put the figures in the link I shared earlier.

edited to add: too late, @timselectric's done it for you!!

 

[AntronX]

What gauge of cable is required for carrying the 387v from the panels 200’?

12 AWG will lose 1.64% after 200ft at 387V 10A.

 

[timselectric]

I would run #10. To allow for future expansion.
This gives you 20a capabilities. At 2.42% voltage drop.

 

[hwy17]

As I understand it, DV losses are always greater than AC losses.

This concept arises from the fact that you can't transform DC so you can't step it up and down easily like AC, making it challenging to distribute.

Apples to apples, 240v AC vs 240 DC for example, they conduct the same over distance.