How many watts should my PV pull in during full sun

nschizzano
nschizzano Registered Users Posts: 34 ✭✭
in General Solar Power Topics #1
Hello I just noticed my Panels only pull in 2 to 103 watts and there is 200 watts worth of panels. I forget how they are wired it was 5 years ago i wired it. But it's for a 12v battery so I think in parallel. I recall seeing on the mppt they were pulling in 180ish watts sometimes but this was years ago. Today I noticed when the battery's are not being pulled on from stuff plugged into the inverter, the mppt reads only 2 or 7 watts from the pv then plunging all electronics in as possible it only went to 103 watts. I just want to make sure my panels are working 100 percent and everything is good and clear in my head. Cables are 8g I think and it's about 50ft. There some dark x spots on the one renogy panel but I tested the back with a multimeter and it showed 19v, what it should be. Any comments or thoughts or words are welcome. Thanks. I'm just trying to wrap my head around all of this fully. 
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  • Wheelman55
    Wheelman55 Registered Users Posts: 244 ✭✭✭
    edited April 22 #2
    You’ll only see watts when the batteries are being charged. 

    Even in full sun, if the batts are at full charge. 

    Try disconnecting the panels, take the battery down to 70%, then reconnect the panels at solar noon on a full sun day. You should see max watts then. 

    Solar noon is half way between sunrise and sunset. 
    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
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  • nschizzano
    nschizzano Registered Users Posts: 34 ✭✭
    #3
    Great awsome. Good one
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,102 ✭✭✭✭✭
    #4
    Don't expect more than 75 - 80% from your panels even at solar noon. As your panels warm up, they produce less than rated power. On a COLD sunny day you can actually get more than rated power.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • JRHill
    JRHill Registered Users Posts: 353 ✭✭✭
    #5
    There are a lot of variables in this subject that go all over the system components. For the panels specifically they are 15 years old now. I KNOW that they aren't delivering what they used to but on the average the difference is mostly trivial. The 'mostly' part is in the temperature part. When they really suffer is on a clear, hot day with no air movement. But then the reduced output is not an issue as the batteries are full by noon. On a clear cool day with a breeze they operate much better. This has always been true, of course, but it seems to be more pronounced as they age.
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
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