my best configuration for busted panel

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mahendra
mahendra Solar Expert Posts: 181 ✭✭✭
in Off Grid Solar & Battery Systems #1
Ok lately on of my 300w panel glass got shattered ,panel still works but don't think that is safe.my present configurations are as follows
6 -250 in series strings of 3
Vmp-around 30v
voc-around 37v
isc-around 8amps
This configuration is on my classic 150

2- 180w in series (vmp-around 36v, voc around 44v and isc -around 5amps)
2-300w in series(vpm-around 36v,voc around 44v and isc-around 8amps)
above on Classic 200

Now since i have a busted 300w panel out of the two 300w panels in series. what is my best solution if any,trying not to replace the 300 w panel or putting it in parallel with the two 180w panels? Reasons:
I am not in a position to replace the panel although i want to
running out of breaker space and copper to run extra cables
i almost forgot my system is 12v nominal and please excuse the panel specs posted. Panels are on the roof cant remember the decimal points for the specs.
Panel got cracked by tree in bad weather.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: my best configuration for busted panel

    In my opinion the best thing to do if removing the broken 300 Watt panel is to put the remaining one in parallel with the two 180 Watt panels. If the Vmp's of these panels are all around 36 +/- 5% it will work fine.
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #3
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    Re: my best configuration for busted panel

    ie put the two 180s and the 300 all in parallel. Distance will be a factor.

    You have 2.5kWp on 12V bat? Thats like 200 amps charging.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: my best configuration for busted panel

    Well the six 250 Watt panels will max out the Classic 150 @ 96 Amps on 12 Volts.

    The 660 Watts remaining on the Classic 200 should add 42 Amps so 138 total, which is plenty for 1080 Amp hours.

    Although 1080 Amp hours @ 12 Volts is a strange (not efficient) way to get 6 kW hours of power.

    One thing you are changing is the current from the array to the Classic 200: the old configuration would have been around (5 Amp string + 8 Amp string) 13 Amps. Now with the two 180's and one 300 in parallel you'll have (5 + 5 + 8 ) 18 Amps. The other will be the array Vmp dropping from 72 to 36 which as zoneblue said may prove a problem if there's an great distance between array and controller (combined effect of dropped Voltage and increased current).

    Worst case: if the Isc's of the panels are close you can put the two 180's and one 300 all in series, giving you a very high array Voc (up to 172 in cold temps so the Classic 200 should handle it) to keep the Voltage up and current down; less line loss but possible decrease in controller efficiency. I don't know why you picked a 200 with an array Voc around 88.
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  • mahendra
    mahendra Solar Expert Posts: 181 ✭✭✭
    #5
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    Re: my best configuration for busted panel

    well i am planning to go 48v but don't have the 48v inverter as yet so that's the reason for all the weird configurations
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  • mahendra
    mahendra Solar Expert Posts: 181 ✭✭✭
    #6
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    Re: my best configuration for busted panel

    also my batteries are agms with a max charge rate of 30% .Deka advise it would be good to get to the 20 % mark charge rate .
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  • mahendra
    mahendra Solar Expert Posts: 181 ✭✭✭
    #7
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    Re: my best configuration for busted panel

    As for maxing out the classic for safety i set current limiting feature and Bob from midnite mentioned it shouldn't be a problem.
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #8
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    Re: my best configuration for busted panel
    mahendra wrote: »
    also my batteries are agms with a max charge rate of 30% .Deka advise it would be good to get to the 20 % mark charge rate .

    A few people have mentioned lately that AGMS that shouldnt be 'tickled'. Mine, often reach the start of absorb at 9.30am, and hence almost never get a chance to reach the 15% charge current that the array is capable of, and not too often even reach 10%. Days between bulk isnt really helping much either, so might have to resort to turning the array off now and then.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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