[RE-wrenches] 24V Module Query

Thu Jan 24 12:51:44 PST 2013

Upgrading to a versatile Midnite or Outback cc seems to me a better investment. Sometimes you can match newer 72 cells with older mods...For example, one new Canadian 280 (35.6Vmp, 44.2Voc) matches up nicely with 2 old Kyo 120's (33.8Vmp, 43Voc)....

Eric
SunHarvest

----- Original Message ----- 
  From: Jason Szumlanski 
  To: RE-wrenches 
  Sent: Thursday, January 24, 2013 12:38 PM
  Subject: Re: [RE-wrenches] 24V Module Query

  I totally agree - old mods are usually not worth messing with at today's PV prices. In some cases it might be best to downsize the system and then AC couple some microinverters to cover the decrease in performance, or just replace the entire array if there are enough problems. There is a used market for smaller PV mods on Craigslist. 

  Back when I was installing Astropower 110W modules on single voltage Xantrex C40's, I never thought we'd be using anything but 12V nominal PV mods. Little did I know... Off-grid is really tough in these retrofit situations, but this applies to failed/broken mods on grid-tie systems as well. That's where I can make a good case for microinverters.

  Jason Szumlanski 

  Fafco Solar

  On Thu, Jan 24, 2013 at 3:11 PM, Ray Walters <ray at solarray.com> wrote:

    Hi Allan;

    I've been in the same conundrum lately.  I found that AEE and others have 12 v modules (Solartech), but the price per watt is double or triple.  My take is that somewhere around 200 to 400 watts, its more cost effective to go to the GT modules with an MPPT controller.  Blue Sky makes the 1524, and 3024 that can take up to 57 Voc, so those would work at still fairly low cost.  Unfortunately many of the other low cost MPPT controllers won't work with the 60 cell modules.  At some point, it may actually be cost effective to just use 60 cell modules with non MPPT controllers, and just forget about the extra 24 cells.  (I know that sounds crazy, but PV less than $1/ watt is crazy too)

    I'm trying to add modules to an existing array of 8 Siemens 12 v modules, and it just doesn't work out, except with separate controllers. 
    Also, its amazing how much PV you can throw at an off grid project these days for $10k.
    It almost makes messing around with the old modules a waste of time.
    Perhaps the solution might be to remove old arrays for customers wanting to really up size, and then reuse the old modules for small systems?

    Ray

    On 1/24/2013 12:35 PM, Allan Sindelar wrote:

      Wrenches,
      We have years of installing 36-cell (12V) and 72-cell (24V) modules for battery-based customers. Most of our systems are 24V or 48V nominal. Over the last few years, sources of conventionally-sized 72-cell modules have dried up - as cells have increased in size, most modules and most newer factory production lines have either gone to 60-cell (20V) modules, or 72 cells in 300+ watt ranges. It seems that the formerly common 72 cell, 24V modules in the 150-190 watt range, which are well-suited to integrating into existing systems, are no longer available.

      60-cell modules in the common 220-250 watt range can't be added to an existing system unless run through a dedicated MPPT charge controller that can convert voltage, such as an FM, XW60, Classic or TriStar; the added cost of any of these controllers cancels out the low prices of the modules.

      Who continues to manufacture 72-cell modules? Which distributors carry them?
          I am aware of three options - are there more?
          - Sunpower makes one module in the 245 watt range that can be used negative ground, but it's very high efficiency (and with high Voc/Vmp as well) and very pricey;
          - Sanyo/Panasonic has 225-240 watt modules, but also quite premium and pricey;
          - Ameresco bought the rights to manufacture many former BP modules, and I think they make some. But we had to replace lots of failed BP modules in that size range, and are hesitant to use their technology, fearing that the problems may persist in the continued line.

      Thank you for any discussion and recommendations.
      Allan

      -- 
      Allan Sindelar
      Allan at positiveenergysolar.com
      NABCEP Certified Photovoltaic Installer
      NABCEP Certified Technical Sales Professional
      New Mexico EE98J Journeyman Electrician
      Founder and Chief Technology Officer
      Positive Energy, Inc.
      3209 Richards Lane (note new address)
      Santa Fe, New Mexico 87507
      505 424-1112
      www.positiveenergysolar.com 

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