[RE-wrenches] Head scratcher

[Rebekah Hren]

Also, it's unlikely in a tiny home, but double-check there are no multiwire
branch circuits. Neutral could be overloaded once L1 and L2 are the same.
There is a required label that states this in Article 710.15(C).


On Tue, Oct 18, 2022, 5:09 PM Vince McClellan via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi Kris
> I've successfully used a double pole double throw relay to handle this
> issue with a couple of solar power trailers that I've built over the years.
> You will need to bridge the inverter side of the transfer switch so that
> the 120V single-phase inverter powers both the L-1 and L-2 buses of your
> tiny home's electrical panel. Also if you use a relay or contactor make
> sure that it is rated for the amperage that you need at *continuous use*,
> or make sure that it is rated for way more amperage than you need. There
> are a whole series of electrical contactors and relays that will say they
> are rated at a much larger amperage than they can continuously handle.
>
> Your transfer switch idea may even work better if you have the physical
> space for it.
>
>
>
> Vince McClellan
>
> Energy Design
>
> NABCEP PV Installation Professional
>
> p. (541) 485-8122  f. (541) 338-8202
>
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>
> On Tue, Oct 18, 2022 at 10:30 AM Kristopher Schmid via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Hi All,
>>
>> I am hoping that someone on the list can help me think this one through.
>>
>> I have a client that builds tiny portable homes.  He is working on one
>> where his client supplied the solar modules, charge controller, batteries,
>> inverter, etc.  They bought them through some dot com.  The tiny home has a
>> 240 volt mini split that they want to use when plugged into the grid.  The
>> inverter that they bought is a 120 volt.  The inverter is not grid tied,
>> but does have a 120 volt grid input for battery charging / pass thru.
>>
>> So, my issue is, how can I make this work?  I am thinking of using a 50
>> amp automatic transfer switch like a Surge-Guard-40100 and connecting the
>> solar inverter as primary and grid as backup but am not sure if that unit
>> will disconnect the grid with only one leg energized.   Physical space for
>> components is very limited
>>
>> If anyone has some ideas here, I would sure appreciate it.
>> (other than "just walk away" or buy a 240 volt inverter)
>>
>> Thanks,
>> Kris
>>
>>
>> Shine On!
>>
>> Kris Schmid
>> Legacy Solar, LLC
>> 137 West 1st Avenue
>> Luck, WI 54853
>> www.legacysolar.com
>> 715-653-4295
>> NABCEP Certified PV Installation Professional
>> Licensed Wisconsin Master Electrician
>> BSEE
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