pianotuna wrote:
Just remember that if the voltage to the controller is doubled, the voltage drop is reduced by 50%. Be aware that losses in the MPPT controller rise with the input voltage. Worst case is about 96%.

I do harvest 17 amps from a 256 watt flat fixed installation, with panels in series/parallel giving a controller input voltage of 33. My line losses between panels and controller are on the order of 1%. They would be much higher if I had gone all parallel.

pianotuna wrote:
two words

Voltage Drop

LipschitzWrath wrote:

Kinda getting off-topic but I never understood this. Even at 12V, 400W = 33A. 10AWG is capable of that, and 8AWG, like I have, is rated to 40A. In reality, panel voltages are higher, which translates to less current, which only improves this.

I guess what I am driving at is I don't understand why people are running 4AWG cable to their panels when they have a 400W array.

Are they just doing it to minimze resistance?

LipschitzWrath wrote:

BFL13 wrote:
You want the 500a shunt not the 100a so when you get the 2000w inverter that is coming next :) you can pull over a 100a and have no issues.

Some places sell the Tri with everything, and some sell the items separately. If you use the 500a shunt as your buss/junction, be aware the bolts in the shunt are quite short and can only hold a few ring lugs stacked at a time, so you might still want the buss/junction to have more places to put ring lugs.

The solar controller that goes with the Tri has a shunt too ISTR and it gets convoluted for sharing shunts and all that. Was a thread about this recently. You are probably ok with the controller you have.

#8 to the roof should be fine, but you will be able to tell once you are out in the sun and check the controller's display for \"expected amps\"

Why on earth does the SC-2030 need a shunt? If connected to the TM-2030, why can't that information be shared? Seems stupid to have two shunts.

BFL13 wrote:
You want the 500a shunt not the 100a so when you get the 2000w inverter that is coming next :) you can pull over a 100a and have no issues.

Some places sell the Tri with everything, and some sell the items separately. If you use the 500a shunt as your buss/junction, be aware the bolts in the shunt are quite short and can only hold a few ring lugs stacked at a time, so you might still want the buss/junction to have more places to put ring lugs.

The solar controller that goes with the Tri has a shunt too ISTR and it gets convoluted for sharing shunts and all that. Was a thread about this recently. You are probably ok with the controller you have.

#8 to the roof should be fine, but you will be able to tell once you are out in the sun and check the controller's display for \"expected amps\"

Almot wrote:
Somehow I missed this:

The good news is the solar kit I bought is easily scalable to 400 watts without any other modifications

Yes, if you route the cable from panels to controller beefy enough for 400W. Especially with PWM controllers.