solar panel not running inverter. im so confused

smarttim21
smarttim21 Registered Users Posts: 2
in Solar Beginners Corner #1
hi guys im very new to the solar industry.

I live in buffalo ny. got plenty of sun lately.
I built my own solar panel using 36 3x6 inch cells I am getting a reading of 18v not connected to anything with the panel sitting outside. then I have a sun 250G grid tie inverter. when I connect the panel to the inverter the voltage drops to around 3v and its not running the inverter. I figured the cells I am using are rated at 1.5watts each they should be enough added up to run this inverter on the inverter it says good to use 10.8 volts up to 22 volts.
so brings the question.... what am I doing wrong??? im confused I tried looking around online and here and cant seem to find anything relating to this kind of problem. any help would be great thank you Tim
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #2
    Re: solar panel not running inverter. im so confused

    Sounds like the most likely problem is in the panel, probably a high resistance connection between cells somewhere, or possibly miswired cells. Try putting a small 12 volt light - 5-20 watts or so - across the panel output and see if it does anything.
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  • WillBkool
    WillBkool Solar Expert Posts: 35 ✭✭
    #3
    Re: solar panel not running inverter. im so confused

    If your voltage drops to 3 volts under load, and the inverter needs a minimum voltage of 10.8v, then you don't have enough volts to run the inverter. Homemade solar cells are not usually the best, especially for grid tie.
    1220 Watts, 4 Evergreen 120 watt, 1 Eoplly 190 watt; 1 Sungold 200 watt; 2 175 Watt; M-Star 15A MPPT; C40 PWM; 6 105 AH AGM Configured to 315@24V
    Cotek 1500 watt/24v
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: solar panel not running inverter. im so confused

    Welcome to the forum.

    First of all your 18 Volt reading is Voltage open circuit, and for a "12 Volt" panel it's low. This is often a problem with homemade panels because you start with reject sells sold on the Internet. No joke. Sounds like at least two of the cells aren't putting out.

    Second, panels are a current source. If you want to really see what it is doing measure the current output into a dead short. With one panel you should be able to do this using a DMM on DC Amps connecting the (+) to the (-) of the panel.

    Third, what are the specs on the inverter? Chances are very good that one 12 Volt panel isn't enough to run it. Most of these micro-inverters require around 30 Volts under load (Vmp - Voltage at maximum power) to function. They also need to be connected to the grid, and there is no legal way of doing that.

    In short this is not something you should even be trying. If you want to learn about solar panels, skip the inverter part. Especially any grid-tie unit. Go for trying to charge a battery; it is simpler, safer, and definitely legal.
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  • smarttim21
    smarttim21 Registered Users Posts: 2
    #5
    Re: solar panel not running inverter. im so confused

    Ok ill be pulling apart this panel to see if i can see anything wrong. I have 20 6x6 cells on order too maybe wire these into another panel but conect the panels pos to neg then into the inverter to step up the voltage.

    Was also thinking bout buying one of thoes harbor freight setups to start and grow off of that?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: solar panel not running inverter. im so confused

    what is it that you wanted to do with solar? unless you want to power a little fan or light bulb occasionally i wouldn't bother with the hf 15w pvs and buiding pvs really isn't a good idea either as you will never match the quality of a commercial pv for the price.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #7
    Re: solar panel not running inverter. im so confused

    20 series cells have Vmp~10 volts... That is just too low to work properly with your GT inverter (I would guess).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: solar panel not running inverter. im so confused

    yikes, i missed that bill. quite obviously the cause.
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