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Old 10-31-17, 10:01 PM   #71
nokiasixteth
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No actual test so far for the system but i got 22 of the 230 watt pannels . Max of 5060/240
22 amps maybe . Dont know if it would ever excede this being i havent put any on the roof . I know 10guage is good for 30 amps . 8 guage is for 40. Distance playing into it i figure i would rather not loose as much through heating up wires over distance to shop to house.
I already have pv 10 guage 200ft this should be enough to get me to the inverter.

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Old 11-01-17, 05:57 AM   #72
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Quote:
Originally Posted by NiHaoMike View Post
Incorrect. It's voltage that determines the efficiency.
Efficiency is the ratio of input power to output power. Higher voltages allow the benefit of finer wire sizes for the same power but we could run larger wire at lower voltages and achieve the same efficiency, cost no object.

AC inverters like the SolarEdge I use run about 350 VDC from modules in series so finer wire can be used with a very high efficiency.

I mount mine in the garage, I agree, very noisy!

Rob
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Old 11-01-17, 10:50 AM   #73
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Quote:
Originally Posted by nokiasixteth View Post
I was under the impression being it was 350 volts of dc it may have a little less drop . It would be less of a voltage drop to the house than 240 volts ac . But also seem to remember tesla and edison ac being more efficient to transfer . I figured i would throw that out by someone who is smarter than i am.. Am going to use 8 guage wire from the shop to the house though . Measured today . From the shop where i was going to mount inverter on shop is 112ft. give or take a couple inches for disconnect box.
I see , had thought the Panels passed out a lower DC voltage like 20 or 24v and high amps but its not like that at all , thanks for pointing that out i stand corrected and gained some insight.

That puts a whole new spin on wiring these panels ! 240v DC who knew (not me)
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Old 11-01-17, 04:21 PM   #74
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Originally Posted by ecomodded View Post
I see , had thought the Panels passed out a lower DC voltage like 20 or 24v and high amps but its not like that at all , thanks for pointing that out i stand corrected and gained some insight.

That puts a whole new spin on wiring these panels ! 240v DC who knew (not me)
Mine show they are 24 volt but looks like they max out around 34 volt. Maybe when they are in direct sunlight perfect condition. Research ive done is way these power optomizers do . The inverter needs 350 volt dc to do its thing. They adjust each ones voltage so that the inverter gets its voltage quickly as possible .The voltages add up so that its 350 volts . In case of shading when one may only be putting out 10 volts . It adds that 10 volts instead of lowering the entire string down to 10 volts. This is my take on them. If im wrong someone who is smarter on this stuff dont be shy to speak up this is the reason i post . Collective knowledge is better than 1 very limited .
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Old 11-01-17, 04:25 PM   #75
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Originally Posted by Robaroni View Post
Efficiency is the ratio of input power to output power. Higher voltages allow the benefit of finer wire sizes for the same power but we could run larger wire at lower voltages and achieve the same efficiency, cost no object.

AC inverters like the SolarEdge I use run about 350 VDC from modules in series so finer wire can be used with a very high efficiency.

I mount mine in the garage, I agree, very noisy!

Rob
This was my thoughts . But the (DC) part is throwing me for the loop. It would probably be ideal for the inverter to be right beside the panel box but . On those days where its shady. I may not get as much power output. (Inverter not getting its cut on) As if i would if i had it right under the panels.
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Old 11-04-17, 06:42 AM   #76
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So for roofing conduit . Is there any code or anything that says that the conduit must be a certain type . And from row to row do you run it on the panel or do you run that through conduit down. Does anyone have any pics of the portion before panels are put down ?
Im trying to get a rough idea of what i need to do to get ever thing right. Already have some 1 inch conduit i can use for the wall of the house . Just ant sure what to use for the roof portion and where needs to have the conduit and type
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Old 11-04-17, 05:37 PM   #77
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Quote:
Originally Posted by nokiasixteth View Post
So for roofing conduit . Is there any code or anything that says that the conduit must be a certain type . Just not sure what to use for the roof portion and where needs to have the conduit and type
For my micro-inverter system, I looked closely at what the micro-inverter trunk cable is, and duplicated the specifications of it. Trunk cable is four conductor sunlight and oil resistant jacketed 12AWG tray cable, which I supported between the rails on custom fabricated and painted aluminum support bars (1/8"x3/4" aluminum flat stock) that I simply screwed to the rails. I then used stainless tie wraps to lash the tray cable to my support bars. (plastic tie wraps didn't have the life expectancy I wanted for the system).

In my case, when I needed to transition cable types on the roof, I went through a Hoffman fiberglass enclosure with UL Listed industrial wire terminals. When my inspectors looked at the connection boxes and didn't find wire nuts, they were impressed by the fact that it looks like it fell out of some industrial installation. When I transitioned from stranded 12AWG trunk cable to the solid 10/3+G UF wire in the attic, I went through more industrial wire terminals inside a PVC junction box.
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Old 11-04-17, 09:45 PM   #78
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Originally Posted by where2 View Post
For my micro-inverter system, I looked closely at what the micro-inverter trunk cable is, and duplicated the specifications of it. Trunk cable is four conductor sunlight and oil resistant jacketed 12AWG tray cable, which I supported between the rails on custom fabricated and painted aluminum support bars (1/8"x3/4" aluminum flat stock) that I simply screwed to the rails. I then used stainless tie wraps to lash the tray cable to my support bars. (plastic tie wraps didn't have the life expectancy I wanted for the system).

In my case, when I needed to transition cable types on the roof, I went through a Hoffman fiberglass enclosure with UL Listed industrial wire terminals. When my inspectors looked at the connection boxes and didn't find wire nuts, they were impressed by the fact that it looks like it fell out of some industrial installation. When I transitioned from stranded 12AWG trunk cable to the solid 10/3+G UF wire in the attic, I went through more industrial wire terminals inside a PVC junction box.
So yours basically rest inside a custom made holder (not conduit) you made on your roof to the junction box then from the box out to the meter it is conduit ?
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Old 11-05-17, 08:18 PM   #79
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Voltage Drop in PV Systems: Page 2 of 3 | SolarPro Magazine

Found this to be kinda helpful.

Seems for a long haul emt will be the most reliable .

Still so far i have not found squat on what i am trying to find out on how i need to run my dc from the last optomizer to the spot where i am going to go off of the roof . My only guess is under the panel just put the wire through it and mount the emt a little bit off the roof so it dont touch and hold trash.
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Old 11-06-17, 12:03 PM   #80
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Originally Posted by pinballlooking View Post
How many amps are you going to be running through that wire? Have you looked distant and amp charts?
You need to be careful about voltage rise. The inverter will increase the voltage to feed it back to the grid. If you have too much voltage rise from using wire not suited for that distance it will just shut down the inverter.

Here this explains some on voltage drop and why it is important
Episode 5 pt 1: Voltage Drop and Wire Sizing for Solar - Affordable Solar

Wire sizing
Wire Sizing Tools and Resources - Affordable Solar
I looked and read through that one . I understand voltage drop . But voltage gain. Im not sure im getting . Unless its the voltage from inverter trying to meet voltage spikes .

The amount of voltage looks like this is perfect scenario . 240 volts output Ac. 350 v input dc according to solar edge . I have 22 230 watt panels. \
So 14.4571 amps dc 15-20 amps would be a theroretical max . To my understanding this almost never happens to pull a max power.

Im reading this
Code-Compliant Conductor Sizing | SolarPro Magazine

And its saying artical 701.1b and things as this instead of plain english and using common sense for most of it .


Seems like if im thinking right that if i ran dc to the house to the meter it would be more efficient with the wire 1 due to voltage. The mppt im not really fully understanding . But 350 volts is whats needed to turn on the inverter if i used a 10-8guage wire i should be fine . With wiring ive always assumed bigger was better.
I ran a simulation for a voltage drop with 350 volts . This was its results .
-------------------------------------------------------------------------------------
1 conductors per phase utilizing a #8 Copper conductor will limit the voltage drop to 0.89% or less when supplying 15.0 amps for 150 feet on a 350 volt system.
For Engineering Information Only:
40.0 Amps Rated ampacity of selected conductor
0.7421 Ohms Resistance (Ohms per 1000 feet)
0.052 Ohms Reactance (Ohms per 1000 feet)
3.5 volts maximum allowable voltage drop at 1%
3.108. Actual voltage drop loss at 0.89% for the circuit
0.9 Power Factor

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