Voltage from 36v to18 in the day

I have my 4-100w panels in two series sets. I find my mppt controller initially recognizes 18 v but i have it wired in 2 panel series and as i understand it the voltage should be double. How can it be detecting only 18volts. In the middle of the day the voltage ramps up to +30 volts and then when the pvs start to become shaded it goes back to 18volts. Any idea whats happening?

Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Welcome to the forum. 

    What controller do you have?  What voltage battery are you using?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • jweslock
    jweslock Registered Users Posts: 2
    I have a 60 amp mppt (rock mars) and 12volt 
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    Sounds like a PWM controller to me. People wonder why these off brand controllers dont do what they say on the box. Moral of the story? stick with name brand stuff.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar