Question about my panel array

Hairfarm
Hairfarm Solar Expert Posts: 225 ✭✭✭
in Solar Beginners Corner #1
I've reached one of those moments when I stared at something too long and become more confused. I'm getting ready to put together my off grid 810 watt PV system.

This illustration will be the way I wire my panels:
Attachment not found.

According to my math, the output in the picture should be:

35.4 volts @ 22.8 amps

Is this correct?

Also, is this a good voltage coming into my Outback Flexmax 80?

My system will be 12 volt because I have 12 volt appliances.

thanks,

Hairfarm
· Share on Twitter

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Question about my panel array

    Yes on all counts. :D

    You're building an array with three parallel strings. Each string has two panels in series, giving 2 X 17.7 Volts or 35.4 Vmp @ 7.6 Imp. Parallel connections up the current to 3 * 7.6 or 22.8 Imp @ 35.4 Vmp total.

    Good rule-of-thumb for MPPT controllers is to have the array Vmp around the "ideal" point for the next higher system Voltage. Thus for a 12 Volt system you want a 35-ish Vmp, and this exactly what you have. It's a good balance between the benefits of higher array Voltage and the losses of having to convert same to lower system Voltage.
    · Share on Twitter
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #3
    Re: Question about my panel array
    Hairfarm wrote: »
    This illustration will be the way I wire my panels:

    You would be well served to use a combiner box with a circuit breaker in each string. --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter
  • Hairfarm
    Hairfarm Solar Expert Posts: 225 ✭✭✭
    #4
    Re: Question about my panel array
    vtmaps wrote: »
    You would be well served to use a combiner box with a circuit breaker in each string. --vtMaps

    By "string" you mean at the end of the parallel connection on the positive and negative wire before it enters the charge controller? I had planned on using a combiner box before the charge controller with two fuses. Is that what you are referring to?

    Do you by chance have a photo you could attach to make it more clear for me?
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Question about my panel array
    Hairfarm wrote: »
    By "string" you mean at the end of the parallel connection on the positive and negative wire before it enters the charge controller? I had planned on using a combiner box before the charge controller with two fuses. Is that what you are referring to?

    Do you by chance have a photo you could attach to make it more clear for me?

    String: the two panels in series.
    After that a fuse or breaker is in-line on the positive lead.
    After that the positives come together to feed the charge controller.

    There are pre-made combiner boxes like these: http://www.solar-electric.com/mnpv3.html
    · Share on Twitter

Categories