[RE-wrenches] Using same PV array for water pump, battery charging

[Kirpal Khalsa]

Hi Larry. We did this recently.  We settled on a Square D 60A 600VDC
disconnect feeding a Midnite Solar Transfer switch with 60A, 300VDC
breakers.  We put an engraved placard on the transfer switch instructing
the customer to turn off the disconnect first then to operate the transfer
switch and when the transfer either way is completed to turn on the
disconnect again. .  It could have worked without the disconnect but we
felt that it was probably an abundance of caution to operate the transfer
switch with PV disconnected.
Our application was switching from a Grundfos pump in the summer to a
Fronius inverter in fall and the reverse in spring. .  This was a seasonal
transfer instead of daily transfer.  Certainly not automated. But
relatively fool proof and safe.
Good luck.

Sunny Regards,
Kirpal Khalsa
Oregon LRT#25
NABCEP Certified PV Installation Professional
Oregon Solarworks LLC
www.oregonsolarworks.com
541-299-0402

On Thu, Feb 16, 2017 at 4:24 PM, Roy Rakobitsch <windsine at gmail.com> wrote:

> Arcing would only happen when disconnecting pump during sunny periods, why
> not disconnect at dusk? Connecting pump will not arc due to soft start. Not
> sure about that particular charge controller,  but some controllers can use
> Aux relay logic to do this upon full SOC. The Midnite Classic comes to
> mind. Swithcing can be done with contactor.
> Just a thought.
>
>
> Roy Rakobitsch
> NABCEP Certified Small Wind Installer®
> Certified Advanced Tower Climbing, Safety & Rescue
> Wind/PV Design Engineer
> Windsine LLC
> 631-514-4166 <(631)%20514-4166>
> www.windsine.org
>
> On Feb 16, 2017 4:24 PM, "Starlight Solar Power Systems" <
> larry at starlightsolar.com> wrote:
>
>> Hello Wrenches,
>>
>> A customer has 3250 Watt PV array @ 139Voc. The PV controller is Magnum
>> PT100. He wants to install a Grundfos SQFlex pump and be able to switch the
>> DC from the PV controller to run the pump directly. He would like to switch
>> midday after the battery (48V) is at a high SoC.
>>
>> I’m looking for a switching arrangement to do this without arcing since
>> it will be used a few times each week. Any have a recommendation?
>>
>> Thank you,
>>
>> Larry Crutcher
>> Starlight Solar Power Systems
>>
>>
>>
>>
>>
>>
>>
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