Wire Gauge Required Question
For some reason I just can't understand the various wire gauge tables, and I have tried to, so I am hoping somebody will take pity and do all the work! :) One table that I can follow says that for...
Forum Discussion
Salvo wrote:
As some mentioned, key in MPPT is power.
P = V * I
If you drop 2% in voltage between panel and controller, you drop 2% power, and you drop 2% battery charging current.
I always us a wire guage table, never a voltage drop calculator. 10 awg wire has a resistance of 1 mohm/ft. 60 ft of cable gives 60 mohm. At 8A, you get a voltage drop of 60 mohm * 8 A = 0.48 V. At 24V, that about a 2% voltage drop. You can expect 2% less charging current in bulk.
In addition, you also got losses in the controller. Usually, the higher the input voltage the greater the losses. If you're concerned about losses, it's better to go parallel/series rather than all series and use a larger cable.
Sal
in the case for a solar connection, cable power loss is related to voltage squared. yes P=E*I. but P= V2/r or I2*R in the case of a cable R is constant. or power loss is related to cable voltage drop squared, not voltage drop or the current in the wire squared.
As I mentioned in a previous post, a 2% voltage drop is a 4% power loss.
