Not sure if its working right

thermax292
thermax292 Registered Users Posts: 23
I've just had a 6 kw system installed, it uses a Xantrex WX6048-120 inverter and two XM-MPPT 60 Solar charge controllers with 27 224 watt Sharp panels. Even on a bright sunny day in August it only puts out around 28-30 kwh's. I get the reading off of the SCC. I've been recording the AH's, time running and KWH's every day to create a log. On the inverter during the day it seldom reaches 5 KW even when the sun is very bright. Sometimes when the sun is really bright I have noticed that the Kw display on the inverter goes to the same display I see at night with the little straight lines. In a few seconds it starts up again and runs normal. I don’t know if that’s normal or not. Shouldn't a 6 kw system give me more KWH's than 3 on a bright sunny cloudless day in August? Thanks so much for your input.

Comments

  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Not sure if its working right

    Your array is 6kw , the XW is reporting AC watts , with an efficiency of about 90% ( 97% on the charge controllers and 93% on the inverter ) that would be 5600 watts which is very good.

    Warm weather and the panels not perfectly aligned to the angle of the sun will easily knock 5-10% off the STC rating of the array

    Just make sure your sell voltage is between 53-54 VDC, if its higher, the kwh sold will suffer
  • thermax292
    thermax292 Registered Users Posts: 23
    Re: Not sure if its working right

    Thanks for getting back to me. The voltage says 52.2. When I went out to check it I noticed the display on the inverter didn't have the KW numbers instead it had 5 dashes just like it does a night. It came back on in a few seconds but I don't know when it started. Could that shut down on the display be a normal function? A while back the whole unit would shut down and I had to kill the breakers to the controllers and turn them back on, and I could hear a relay click in and the unit started up again. The company that installed it sent a tech out and he did something to it ( I wasn't here) and it hasn't shut down like that since. He said the software needed updated, which they are going to do in the next week or so. I've learned allot about this unit but have a real long way to go in under standing and trouble shooting it. Since I'm only getting 1/2 the power its rated at I have to wonder if it's tweaked out yet. I wish Xantrex had a home owners simplified explanation of their products and how to read their displays and what they mean. Thanks again
  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Not sure if its working right

    Your production isn't far from expectations. In general 4-5X the STC rating of the array is ballpark for expected daily performance. So 30kw is normal for a system of that size

    If your just looking for GT system, the XW isn't the typical choice as it has backup abilities. The one thing to look out for is undersized battery's. You should have 600ah @ 48V battery bank. Smaller than this will lead to odd performance variations and faults.
  • thermax292
    thermax292 Registered Users Posts: 23
    Re: Not sure if its working right

    I'm not sure what the strength of my battery bank is. I have 8-6 volt Rolls batteries,this is what's on the side of them:

    415 AH @ 20 HR
    444 AH @ 72 HR
    460 AH @ 100 HR
    The company that installed the system said I could go about 3 days on the loads panel with a full charge on the batteries.

    I think the charge voltage is 51.8 v. I don't know yet how to calculate their power. I think this is right. I know AH is amp hour and that there are 1000 watts in one amp. I could run 10-100watt bulbs for 1 hr. 414 AH= 41,400 watts. I could run 100, 100watt bulbs for 4,140 hrs.
    Today was partly cloudy and controller 1 harvested 205 AH and 10.7 KWH and controller 2 harvested 254 AH and 10.7 KWH,

    That gives me a total of 459 Ah and 24 KWh's. 459X51.8 volts = 23,776.2 watts of usable power. If my batteries were depleted that would be enough power to totally recharge them? At that rate I could technically go off the grid under today's conditions as long as I didn't exceed 24 Kw's
    on the load panel ? Of course I didn't figure in the fact I only harvested 24 KWH and that would probably keep the batteries up but at the same time my home is sharing the 24 KWHs to keep every thing running. So 24 is not totally going into the batteries?


    Thanks again