Voltage vs. PWM controller & wire size
Ok, there is a recent thread out there MPPT vs. PWM and some post were a little confusing to me. Instead of hijacking his thread I started a new one. My set up is two 208 watt Sony panels with 28....
Forum Discussion
Almot wrote:
GD - I think his 10ga part of the rant was about "solar" part, i.e. from panels to batteries. Here 3% is fine with PWM. With MPPT it wouldn't affect the charging voltages at all - but 3% V-drop would mean 3% AH loss then.
I would tend to agree the 10 ga was part of the solar "rant" BUT overall minimizing any line loss between solar panel to controller to the batteries is just as important.
Up sizing the wire has NO "draw backs" other than a small additional cost provided the path the wire will accommodate the up sized wire.
You gain the benefit of being able to move the max amount of current/voltage from panel to the controller to the batteries to the inverter. A "Win - Win - Win" for the entire system.
Lets face it, when playing off the grid, the cheapest thing you can do is CONSERVE. One of the ways to conserve is to reduce the voltage/amp loss in the wiring resistance.
Pay once and it returns benefits 24/7.
If the OP has a beef in the cost to up size the wire, there are lots of surplus electrical/electronic dealers which often have very good wire pricing.. That is how I got 1/0 Extra flex wire for my inverter for about $1.80 per foot.. At that time my local welding supply wanted $3.50 per ft for 2 ga welding wire..
HERE is a place where you can get some killer deals on wire!
In that link the price of 10 ga high strand flexible wire is $.47 per ft..
But you can up size to 8 ga for $.61 per ft..
Sure you invest a little extra into the up graded size wire but in the end less line loss is a bit like getting a slightly higher wattage panel.. Important to folks with very little space on the roof to work with..
After all, if you put the money into a 200W panel why wouldn't you want to get as much of the 200W you paid for?
