donb108
New Member
Last year, I installed a completely stand-alone system on my shed. The shed is insulated, wired, has ground rods, inverter, battery, etc.; it works great. But, I don't use most of the power it could be making, so I'm changing my setup and rewiring the panels to connect to a new system I'm planning for the house. I'll be runnnig the sheds PV wires to the new inverter, and power wires from the inverter back to the shed. We also want to add cameras to the shed, so I'll include a fiber optic line in the conduit.
The wire run is about 235', with 135' in underground PVC conduit (house to shed). I think I need 7 conductors (power, PV, fiber), but I don't have much experience with long runs, so I used online calculators to size wires and conduit.
Do these results look reasonable?
Panels:
All 8 shed panels are connected in series (panel VOC is 41.75Vdc). Typical running PV voltage is 230Vdc-280Vdc and Isc is 11.25amps. They're currently wired with 12 gauge PV wire.
-The calculator says to use 10 gauge, so I'll use (2) 10 AWG THWN stranded (19 strands).
Power:
The existing breaker box is feed with 10 AWG, directly from the EG4 3K inverter (at 120Vac) to a 30 amp main breaker in the panel. I'll replace those wires with a feed from the new inverter. I'll also add a conductor and change to 240Vac. Plugging 240Vac, 5%, and 30 amps into the calculator:
-The Southwire calculator says to use 8 gauge, so I'll use (3) 8 AWG THWN stranded (hot, hot, neutral) + (1) 10 AWG THWN stranded (ground).
Conduit:
The fiber optic cable is 5mm, which is similar to 8 AWG. I calculated for PVC (sch 40), with (4) 8 AWG and (3) 10 AWG.
-The Southwire conduit calculator says to use 1" PVC, with fill of 24.48%.
For reference:
Panels on a shed:
Raising panels:
Solar Wire Size Calculator
solarwiresizecalculator.com
Southwire: Calculate Your Voltage Drop
www.southwire.com
Southwire: Calculate Your Conduit Fill Percentage
www.southwire.com
The wire run is about 235', with 135' in underground PVC conduit (house to shed). I think I need 7 conductors (power, PV, fiber), but I don't have much experience with long runs, so I used online calculators to size wires and conduit.
Do these results look reasonable?
Panels:
All 8 shed panels are connected in series (panel VOC is 41.75Vdc). Typical running PV voltage is 230Vdc-280Vdc and Isc is 11.25amps. They're currently wired with 12 gauge PV wire.
-The calculator says to use 10 gauge, so I'll use (2) 10 AWG THWN stranded (19 strands).
Power:
The existing breaker box is feed with 10 AWG, directly from the EG4 3K inverter (at 120Vac) to a 30 amp main breaker in the panel. I'll replace those wires with a feed from the new inverter. I'll also add a conductor and change to 240Vac. Plugging 240Vac, 5%, and 30 amps into the calculator:
-The Southwire calculator says to use 8 gauge, so I'll use (3) 8 AWG THWN stranded (hot, hot, neutral) + (1) 10 AWG THWN stranded (ground).
Conduit:
The fiber optic cable is 5mm, which is similar to 8 AWG. I calculated for PVC (sch 40), with (4) 8 AWG and (3) 10 AWG.
-The Southwire conduit calculator says to use 1" PVC, with fill of 24.48%.
For reference:
Panels on a shed:
Once again, still working on my shed project.
diysolarforum.com
This is a small, off-grid, EG-4 3K system. I plan to have roof and wall mounted panels, which I've already purchased from Santan Solar. While checking into racking, one of the vendors mentioned that panels needed to be a minimum of three feet from the roofs edge.
However, I've seen lots of youtube's showing similar projects, and spacing about the same as mine. And, this is an unoccupied structure that isn't connected to the house. Is the three foot thing...

Quick EG4 3K question
I'm still working on my shed project and came across a little confusion. https://diysolarforum.com/threads/wiring-question-for-120vac-system.74764/#post-949618 EG4 provides a 125 amp breaker with the 3K inverter, and shows instructions on how to wire it. But, Will's video doesn't use it...

This is a small, off-grid, EG-4 3K system. I plan to have roof and wall mounted panels, which I've already purchased from Santan Solar. While checking into racking, one of the vendors mentioned that panels needed to be a minimum of three feet from the roofs edge.
However, I've seen lots of youtube's showing similar projects, and spacing about the same as mine. And, this is an unoccupied structure that isn't connected to the house. Is the three foot thing...
- donb108
- Replies: 13
- Forum: DIY Solar General Discussion
Raising panels:
Still working on my shed project (off grid, EG4-3K, 8 panels). I have four panels on the roof and four on the back wall, all in a single string of 8, and facing south. The wall mounted panels tend to limit production of the entire string. Since the wall mounted panel assemblies are hinge mounted, I can lift them up with a 2x4, and production goes way up (900watts vs. 2400watts).
Lifting the panels with a 2x4 is difficult, so I'm trying to use gas-struts instead. I've tried three different sets of struts from Amazon and none are working quite right. The first set was way over powered...
Lifting the panels with a 2x4 is difficult, so I'm trying to use gas-struts instead. I've tried three different sets of struts from Amazon and none are working quite right. The first set was way over powered...
- donb108
- Replies: 17
- Forum: DIY Solar General Discussion
Solar Wire Size Calculator
The Solar Wire Size Calculator
Southwire: Calculate Your Voltage Drop
Voltage Drop Calculator | Southwire

Southwire: Calculate Your Conduit Fill Percentage
Conduit Fill Calculator | Southwire
Get accurate conduit fill percentages with Southwire's Conduit Fill Calculator. Perfect for electricians, engineers, and contractors.
