grid tie panel size

Options
2»

Comments

  • softdown
    softdown Solar Expert Posts: 3,821 ✭✭✭✭
    #32
    Options
    Thanks....I hope the OP reads this. Sounds like he is cognizant and that may be why he has Midnite leanings.

    I put down my Outback bias and studied the Midnite stats. Seems to be a superior controller. May give it a run with the next solar array.

    I like the fact that voice prompts walk one through things. I am not a superior electrical techie. Just slowly muddle through and usually get lucky with persistence.
    Vic wrote: »

    The low temperature recorded for those times, was about +20 F.

    All of the PV modules in use at that time were Shell Solar SQ175PCs. These run an STC Vmp of 35.4 V, and 44.6 Voc.

    Running strings of three of these PVs is at the very hairy edge of acceptable. Only works in very moderate, temperate environments. AND, the lightly-loaded string Vmp (really approaching Voc for the temperature of the PV, while operating) easily runs into the 122 V range, as input to the CCs. This is an efficiency hit of several percentage points.

    Of course, using higher voltage-tolerant CCs increases the flexibility of the string configuration.

    Chose this configuration, because the longest run from the PVs into the CCs was about 80 feet, and wanted to be able to use PV string voltage to heat domestic water, directly.

    The PV racks are on a roof that is about 75 feet long.

    In general, this three PVs per string configuration will NOT work for many applications. Furthermore, the current 72-Cell PVs have even higher Vmps -- about 36.5 V, and some have about 1 V higher Vocs, even more marginal for current production PV Modules. Some have about 1V lower Vocs, but not recommended, for CCs with 150 V absolute maximum PV input voltages.

    With your very cold seasonal temps, strings of three with an FM, or other 150 V Max input CC, are of course are out of the question.

    FWIW, Vic

    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
    · Share on Twitter
  • levsmith
    levsmith Solar Expert Posts: 56 ✭✭
    #33
    Options
    softdown wrote: »
    Thanks....I hope the OP reads this. Sounds like he is cognizant and that may be why he has Midnite leanings.

    I put down my Outback bias and studied the Midnite stats. Seems to be a superior controller. May give it a run with the next solar array.

    I like the fact that voice prompts walk one through things. I am not a superior electrical techie. Just slowly muddle through and usually get lucky with persistence.



    I read it!

    I don't have any experience with any brands of cc's. I have been researching alternative energy off and on for years and was originally drawn to outback but now that my plans are starting to be put in motion, I have been doing extra research. After lots of reading, I keep hearing people agree that midnite is a step above the rest, that is the only reason I am leaning towards them, and the fact that they haven't been bought out by a big corporation sure doesn't hurt...

    I sure appreciate everyone's help, I got a hold of the local installer today and found out they normally use 260 watt panels on their grid tie installs and according to midnites string calculator, it looks like those will work just fine with strings of 3 using the classic 150.

    Also I think I will now be building a small storage building probably on the north side of the panels to store the mower and atv and I can also have a spot for my alt-e equipment and batteries in there to avoid the 150 ft DC run to the house. I probably will have some questions on the storage building since it won't be climate controlled but I will probably start another thread on that soon. Thanks again for everyone's help, if you have anymore opinions don't hesitate to post them
    · Share on Twitter
  • softdown
    softdown Solar Expert Posts: 3,821 ✭✭✭✭
    #34
    Options
    An uninsulated storage building will be hot for months and cold for months. Easy to insulate. I put black rubber on my generator shed roof to help during the winter. Then I cover it with a white tarp during the summer. Throw tires on it to give a poor look...and hold down the tarp. I'm in the boondocks so nobody usually sees it. It houses a Kubota/Yamaha diesel. Soon....my 24 volt forklift battery. Heat kills both batteries and electronics. Batteries also perform quite poorly when cold.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
    · Share on Twitter

Categories