New system setup

dedgededge Registered Users Posts: 4
I'm looking to setup a new stand-alone system and I'd like some input...

Raw Materials:

8x Trojan T105REs
3x Chaori 280W
Midnite Solar KID
Xantrex Prosine 1800

I am new to all of this. I believe these are all good components individually, and I'm confident we've sized the battery bank to our needs. Am I light on solar (I'm in Prescott, AZ)? I'm setting this system up for a small travel trailer that we'll be living in full-time while building a home. I'd appreciate any input or tips from folks.

Thanks,
Dave

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New system setup

    Welcome to the forum Dave.

    What system Voltage were you planning on? As far as I know Prosine inverters come in 12 and 24 Volt. Eight Trojan T105's would be bad in 12 Volt: four parallel strings. Not so bad in 24 Volt: two parallel strings.

    At 225 Amp hours each that would make a 24 Volt battery bank 450 Amp hours. Right there the MidNite Kid is out as it is a 30 Amp controller and you should have 45 Amps peak current for that bank.

    Three 280 Watt panels would total 840 Watts, but you have to watch the specifications here: most panels of that size are Vmp around 30, which is too low to properly charge a 24 Volt system. So if you string them all in series you get a different problem: less controller efficiency due to the ratio between array Vmp (which would be around 90) and system Voltage. But there's another, bigger problem: you'd only get about 27 Amps out of that and it's not enough for 450 Amp hours of battery.

    So it's time to recheck the battery capacity and configuration and adjust the PV & controller accordingly.
  • dedgededge Registered Users Posts: 4
    Re: New system setup

    Thank you for the quick response and some much need (obviously!) help. Based on the specs listed, the Chaori Vmp is 35.7. What would you say to going with 4 of them 2x2 and upgrading to the Midnite Classic 200?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New system setup
    dedge wrote: »
    Thank you for the quick response and some much need (obviously!) help. Based on the specs listed, the Chaori Vmp is 35.7. What would you say to going with 4 of them 2x2 and upgrading to the Midnite Classic 200?

    Well 35.7 Vmp works on a 24 Volt system. Have we established that is the intended system Voltage?
    If so a Classic 150 (you don't need a 200; it's for higher input Voltage) would handle the required (based on the battery configuration) 45 Amps (10% peak charge rate). To get that you'll need about 1400 Watts.

    Four 280 Watt panels = 1120 Watts. Expect about 36 Amps from that or 8% charge rate. Technically that would work, but it's a bit light and concurrent loads will bring that rate down (power goes to loads instead of charging). Now in Arizona you'll have plenty of sun, so it just might work. Providing the loads don't get in the way. Not planning on running air conditioning from it are you?

    If you could go six panels you'd have more than enough, but you'd also need a combiner box with breakers or fuses to protect the three parallel connections.
  • dedgededge Registered Users Posts: 4
    Re: New system setup

    Yes, let's stick to 24v. We don't have any heavy loads to run, perhaps a vacuum at some point, lol. We don't have much use for AC. I was thinking we might get one of those portable swamp coolers if we can afford the wattage. I think considering our usage during peak charging time will be very minimal, this may work for us.

    If we are good at 35.7 Vmp should we not go to 2x2?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New system setup
    dedge wrote: »
    Yes, let's stick to 24v. We don't have any heavy loads to run, perhaps a vacuum at some point, lol. We don't have much use for AC. I was thinking we might get one of those portable swamp coolers if we can afford the wattage. I think considering our usage during peak charging time will be very minimal, this may work for us.

    If we are good at 35.7 Vmp should we not go to 2x2?

    Yes, with the MPPT controller 2X standard Vmp is about the most you want to go.

    You'll have a fair amount of power on hand at 450 Amp hours & 24 Volts: at 25% DOD it's about 2.5kW hours. This is actually more battery capacity than I have and I can do quite a lot with my little system. For several years I got by on 700 Watts but this year I pushed it up to 1220 because most of my loads are during the day; the batteries keep things going 'til the sun gets on the panels the next day.

    If that happens. It's been generator weather here.
  • dedgededge Registered Users Posts: 4
    Re: New system setup

    We are planning to use this system for our house when it's finished with a front loading washer and some other simpler (lower usage) conveniences.

    I'm sure you're cursing the clouds. Be thankful for the water, we'll be hauling ours. And thanks again for all the help.
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