[RE-wrenches] 600V charge controller questions

[Roy Rakobitsch]

Allan, you could network multiple Morningstar 600v controllers for the
output ampacity required (up to 4 controllers, ...yeah, I know they are
expensive).

Would you even need a transfer switch? Why not just wire Fronius IG and
Morningstar controller inputs in parallel (with associated fuses and
disconnects of course). Once batteries are charged and in float, the array
then would be available to the IG to sell to the grid. If the IG goes down
(which it prob will eventually) then the MS 600v controller will charge the
batts enough to get by. Seems like it would work, am I missing something?

RoyR

Roy Rakobitsch
NABCEP Certified Small Wind Installer®
Certified Advanced Tower Climbing, Safety & Rescue
Wind/PV Design Engineer
Windsine LLC
631-514-4166
www.windsine.org




On Sun, Jan 31, 2016 at 1:14 PM, Ray Walters <ray at solarray.com> wrote:

> We were called in on a system similar to this, and we ended up just
> installing an AC transfer switch.  Normally the GT array sold back to the
> grid side of the system, but in an extended outage, the customer had the
> option to switch the connection to the back up load side (AC coupled)
> He was made aware that battery regulation could be an issue, and to switch
> off the GT array when the batteries got even close to full.  Obviously this
> would not be acceptable in a full time off grid system, but this option
> could save your bacon in the very occasional long outage.
> It boils down to:  Is it better to let the batteries remain discharged and
> the customer to have no power, or take a chance on over charging the
> batteries in an emergency?
> Essentially, the system would remain full proof until they manually
> switched in the AC coupled system.  I look at this sort of like any other
> manual over ride switch: don't use it unless you understand the
> consequences, and really need it.  Add strongly worded warning stickers: "
> Danger Battery damage could result, Emergency use only!"
> The other options you are considering would certainly be better, but at
> significantly more cost.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer303 505-8760
>
> On 1/30/2016 3:21 PM, Allan Sindelar wrote:
>
> Wrenches,
> I am serving as a consultant for a homeowner with an array of solar
> equipment that doesn't do what he wants, a common story. He wants
> independence in the event of an extended utility outage. To cut to the
> chase:
>
> He has one array of 3,100 watts feeding through a controller into a 48V
> battery bank. No issues with this.
> A second array of 4,230 rated watts (2 9-module strings of 235W Sharp
> modules) currently feeds a Fronius IG-4000 inverter and the grid. In the
> event of an outage this system shuts down, of course. He is looking at
> replacing his existing pair of old SW5548s with a single Schneider XW
> system, or possibly a Radian.
> I would like to give him the ability to switch from the Fronius inverter
> to a 600V charge controller if either a) the grid went down or b) the
> Fronius failed.
>
> I looked at Morningstar's TS-MPPT-600 controller with the DC transfer
> switch, but its DC output is rated as limited to 60A, less than the 4.2kW
> output of the array. The spec sheet gives a nominal maximum wattage of
> 3,200W, although a note adds that "input power can exceed Nominal Maximum
> Operating Power, but controller will limit and provide its rated continuous
> maximum output current into batteries. This will not harm the controller."
>
> I looked at Schneider's XW MPPT80 controller, which has the necessary
> higher capacity. But beside lacking any built-in or optional input
> metering, it lacks the transfer switch available with the Morningstar.
>
> So questions:
> - Is there a good transfer switch to use with the Schneider unit, to allow
> manual switching of the PV input between the Fronius (when the grid is up)
> and the controller and batteries (when the grid is down)?
> - Should I use the Morningstar unit, recommending that the periodic
> flatlining due to the excess wattage be simply accepted as a small
> concession to being able to use the array during an extended outage?
> - Is AC coupling simply a better approach?
> - Any other solutions?
>
> Thanks, Allan
>
> --
>
> *Allan Sindelar*
> allan at sindelarsolar.com
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> *505 780-2738 <505%20780-2738> cell*
>
>
>
>
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