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voltage drop on dc 10 gauge wire?

michael d

off-grid solar pilgrim
Joined
Dec 15, 2019
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Location
South Dakota, USA
I still don't understand the voltage drop calculations. the 2 panels in parallel come into the DSSR20 at around 36 to 39 volts. this is on a 60 feet run.
each dssr20 cost about 37 Canadian dollars 91 Canadian dollar is currently .79 Us dollars so the DSSR20 is 37X.79=$29.23 to control 500 watts although that number could be larger with 72 cell panels @ say 320 watts each or more.
I am not debating what you should use or not use one way or another. sorry to bother you.
I see about 16 amps on 2 panels as the SBMS0 (BMS0 monitors and controls it so it does not overcharge the battery). when it hits the 24-volt lifepo4 battery it charges it with all of the amps that come thru it.
so to calculate and measure the actual voltage drop percentage of 60 feet of 10 gauge PV dc wire???? how much voltage drop I would need to measure the voltage right at the panel and the voltage at the Dssr20 to measure the voltage drop on the 60 feet run correct?
what do you think I should do--- post this question on the forum? to hopefully get an answer/explanation?
I will study up some more.
your attention has been appreciated.
thank you
yes, I agree the MPPT Outback solar charge controllers are way overpriced to control very few solar panels, as are the Victron, and midnight solar. so then you have to cheap out on some unknown unproved other branded ones.
the voltage you are talking about 350 dc volts is more than I care to play with. 24-volt and 48-volt dc system builds are plenty for this DIY person at this time.
the DSSR20's are shut off by the SBMS0. no current goes thru the SBMS0 to speak of.

the SBMS0 was showing 1162 watts at 42 amps coming in. yesterday January 13th, 2021 in the sun. this picture below is 6 panels 250-watt 60 cell used panels in sets of 2 paralleled at the array.
when I measured the voltage of the 2 panels after the 60 feet run they come in at 36 to 39 volts.

any help is always greatly appreciated. the forum is like email. any small word can be mis-typed and mistaken. so I try to write as correctly as possible. forgive me in advance! :cool:
 

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DC / single phase calculation​

The voltage drop V in volts (V) is equal to the wire current I in amps (A) times 2 times one way wire length L in feet (ft) times the wire resistance per 1000 feet R in ohms (Ω/kft) divided by 1000:

Vdrop (V) = Iwire (A) × Rwire(Ω)

= Iwire (A) × (2 × L(ft) × Rwire(Ω/kft) / 1000(ft/kft))

The voltage drop V in volts (V) is equal to the wire current I in amps (A) times 2 times one way wire length L in meters (m) times the wire resistance per 1000 meters R in ohms (Ω/km) divided by 1000:

Vdrop (V) = Iwire (A) × Rwire(Ω)

= Iwire (A) × (2 × L(m) × Rwire (Ω/km) / 1000(m/km))

this was in a link on Lowes rapid tables.
 
I studied up a lot and find the voltage drop is not an issue on the 60 feet 2 wire runs of 2 250-watt panels in parallel using red and black 10 AWG solar PV wire...
this still readily charges the LifePO4 battery without any issues....using the Electrodacus DSSR20 charge controllers

soon he will have Electrodacus DSSR50 which will allow higher wattage panels to charge & to better match up in the off-grid PV systems....

but I do appreciate your efforts and that gave me the push to learn more about all these things....
thanks
lots of helpful folks on this forum who sometimes guide the neophytes in the best directions,,,,
typing is often hard to present the right context....
English composition and speech class were my most difficult subjects back in the day...?

it is snowing out again so have to clean the snow off tomorrow...
the ground mount is best for snow removal I guarantee you,,,
no roof mounts in the northern snow country are advised...IMO
have a great day ?
 
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