Re: Help Sizing Small Off Grid System
I like the prosine units and I think you'll like them too!
Originally Posted by nch18
The Charge Controller(CC) should be fine. They work on the amperage and for the most part you need only worry about presenting (inputing) too much voltage, Voltage Open Curuit (VOC) rather than Voltage Maximum Power (VMP). Likely you will need to run the panels in strings of 2 or 3 for the Tri Star MPPT Charge controller (be careful Morning star has similarly named PWM CC's)
Since watts = Amps x Volts and your running a 24 Volt system... your looking at inputing 2 strings at 7.43A at 3x29V=87V or @15Amps max and outputing 215 watts x 6 for an array of 1290 watts / 24V = 53.75 Amps (your batteries may actually drop lower in voltage and your panels can produce more current on cold clear days, but you have a safe margin)
You can check the CC to see what the max input voltage is, this will be the VOC X the number of panels in the string. 35.6V x 3 in this case might be too much.
Other factors before you buy a CC will be how far your CC will be from the batteries, since higher voltages allow lower voltage drops on the same size wires.
Home system- 20 - 200W Evergreen blems, 2 Classic Lites, E-Panel up! 14 Suntech 185W in spare room.
Cabin system- 8-115watt 12V, 6 - 170-5watt 24v, Pulse/Trace PC250 Power Center, 800AH 24V forklift Batt, ProSine 1800 watt (24v) inverter.
Odds and extras, Rouge CC, 80-4/5watt 6v panels