Too many Panels, so little Time...

[Brucey]

I suppose I'll just pony up for the Victron 100/30 and quit trying to reinvent the wheel.

The 100/20 is only rated for 280watts @ 12v
The 100/30 is rated for 440watts @ 12v

Bottom line.

You may want to consider the small premium and get the 150/35. Gives you flexibility to expand out to a 48V system in the future and more flexibility on voltage also.

 

[Hedges]

Ok, lets try to simplify this, there are 3 aspects to Electricity: Voltage, Amps and Ohms (resistance), the relationship is defined with Ohm's Law.

Also consider water hammer, and its electrical analogy.

Heat generation is going to be from amps not volts, so the 50v/10a wires are not going to dissipate as much heat. The 12.5v/40a wires on the other hand are going to create 4 times the heat, thus need a larger conductor. Over-simplified, but that's the idea.

Rather important here:

For the same wire, 40A won't make 4 times the heat as 10A. It will make 16 times the heat.
W = I^2R

 

[Sundog33]

You may want to consider the small premium and get the 150/35. Gives you flexibility to expand out to a 48V system in the future and more flexibility on voltage also.

If I wanted to go 48v I would have no issues. The Victron 100/20 can handle
1160watts and 20amps at 48v.
And my 39v / 9.38amp panel would be no problem.
The problem arises when you’re using it at 12v. That changes the amp load
Which I like because I have a lot of 12v lighting I draw off of it.
Plus don’t need the expense of buying 4 batteries
For people who say that doesn’t effect the amps they have not tried it in real use

 

[Sundog33]

A simple trip to an internet amp calculator will tell you

12volts @ 300watts = 25amps
39volts @ 300watts = 8 amps

its not that the Load is pulling more Amps
if something is rated for say 1 amp, that rating is for 120volts
if you are asking it to run 1 amp and the supply is now only 12volts
then the amps it will want to draw is 10 amps

the Load is still really only using 1 amp but, because the voltage is so low
it has to balance itself out in order to supply the Loads requirements.

 

[Sundog33]

You want to go the other way it's the same, so if your chainsaw is the load and you need say 120v@10a that's 1200W P = E * I. So if your inverter is being fed from 12V batteries it will requiore P = E * I , 1200 = 12 * I, I = 100A, which is why a "1200W" inverter that plugs into your cigarette lighter on a 20A fuse is completely ludicrous, but I digress. So yes, your inverter or SCC/MPPT is converting the power by stepping up/down both voltage and current. An MPPT/SCC will control total current to the batteries by adjusting the resistance of the load. An inverter will simply trip a breaker if you try and draw too much current (or overheat and burn up if not properly protected).

Ya, not a good idea to mess around out of spec of the charge controller.
I’ll find something to do with these extra Panels. Can’t complain.
again they are selling at $88bucks a piece for a 10 pack on Signature Solar. Just insane!

they are not the most efficient, I only saw 800watts out of my 1200watt array.
But for the price i‘m very satisfied.

 

[Sundog33]

Almost 1000watts out of the 1200watt setup. Not bad.