[RE-wrenches] GT w/ BB

Tue Sep 19 08:49:13 PDT 2023

For a general rule of thumb, I use NEC 366.23 "ampacity of conductors in
sheet metal gutters". For anything large or needing inspection, I have my
electrical engineer design the bussing as he will factor energy density and
temperature rise across the bussing. It's pretty straightforward for DC
bussing, whereas AC bussing needs inductance and skin effect taken into
consideration. It costs me about $1,500.00 to get a stamped design.

On Tue, Sep 19, 2023 at 7:12 AM Jay <jay.peltz at gmail.com> wrote:

> Thx Michael
>
> How do you calculate buss bar size?
> Is there a specific formula or table I can find?
>
> Thx
> Jay
>
> On Sep 18, 2023, at 5:15 PM, Michael Morningstar <mjmorningstar at gmail.com>
> wrote:
>
> 
> I've been making gutter bus wireways that run the length of batteries and
> inverters allowing for exact lengths of cables. I think I posted a picture
> of an exceptionally large one. 24' long. I'm looking at the rack mounted
> set up because the bussing and cabling is done. 3 racks of 6 5kwhr
> batteries. All I will need is cabling from the racks to a small (in size)
> bussbar
>
> On Mon, Sep 18, 2023 at 3:50 PM Jay <jay.peltz at gmail.com> wrote:
>
>> Sounds like a good design.
>>
>>
>> As a tangent question to 13 parallel batteries, such as you’ll need
>> Michael.
>>
>> How are people wiring larger numbers of lithium batteries together in
>> parallel?
>>
>> Massive buss bars which I’m not sure how to do in a code compliance way.
>> Or
>> Not worrying about different cable lengths?
>> Or
>> Adding another conductor to the farthest batteries to compensate for VD
>> Or
>> Making all the cables the same length?
>>
>> Thx
>>
>> Jay
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Sep 18, 2023, at 4:37 PM, Michael Morningstar via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> 
>> Jay,
>> I'd like to design for 60kw supply and 100kWh battery. I think I'm going
>> to try the Discover rack mount set up rather than AES's and custom bussing.
>> Jason,
>> That's exactly what I was thinking, if I go the Sol-Ark route. Last time
>> I ordered custom panelboards like that, they were six months out.
>>
>>
>> On Mon, Sep 18, 2023 at 1:18 PM Jay via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>>> If 40kw is the peak and then there are new added loads, what 50-60kw?
>>>
>>> If it was me I’d be designing the inverters to handle the 50/60 kw with
>>> future expansion capabilities beyond that.
>>>
>>> Then how much kWh of storage are you going to need or maybe are planning
>>> for?
>>>
>>> At some point maybe looking at a larger single inverter with high
>>> voltage battery vs 48v?
>>> I’m not sure if there are any 120/240 versions yet.
>>>
>>> Jay
>>>
>>>
>>>
>>>
>>>
>>> On Sep 18, 2023, at 12:36 PM, Jason Szumlanski via RE-wrenches <
>>> re-wrenches at lists.re-wrenches.org> wrote:
>>>
>>> 
>>> I like the Sol-Ark idea having had a few dual-unit successes recently.
>>> In terms of combining them, the Sol-ark manual has a good triple unit
>>> wiring diagram on page 53. You would have to use two 400A panelboards with
>>> three 200A breakers for each to follow this diagram. However, I don't see
>>> the point of a combining load center on the load side of the paralleled
>>> units. The Sol-Arks each have a 200A integrated load breaker, so why not
>>> just combine the outputs in a multi-tap connector or busbar? I think there
>>> is a code-compliant way to make that work, but I haven't studied it with
>>> three units.
>>>
>>> I would definitely ditch the SolarEdge inverters and just make it DC
>>> coupled to the Sol-Arks. You don't need these to be a failure point in the
>>> system, and the AC coupling will reduce the energy production in backup
>>> scenarios.
>>>
>>> It sounds like you would have to get the six 200 feeders out of the
>>> meter/main and into a new panelboard on the load side of the Sol-Arks. So
>>> that's another required load center.
>>>
>>> And if money is truly no object, I would consider a manual transfer
>>> switch to bypass the inverters for service. I'm afraid to look up what a
>>> 400A DPDT switch costs.
>>>
>>>
>>> Jason Szumlanski
>>> Principal Solar Designer | Florida Solar Design Group
>>> NABCEP Certified Solar Professional (PVIP)
>>> Florida State Certified Solar Contractor CVC56956
>>>
>>>
>>> On Mon, Sep 18, 2023 at 1:14 PM Michael Morningstar via RE-wrenches <
>>> re-wrenches at lists.re-wrenches.org> wrote:
>>>
>>>> I've been asked to build a back up system for a grid connected estate.
>>>> We haven't done many of these and I thought it best to ask those who have
>>>> some questions before I go about reinventing the wheel.
>>>>
>>>> Here's the existing infrastructure.
>>>> 1) 400amp Metered Main Distribution Panel with six 200amp feeders to
>>>> various sub-panels on the property
>>>> 2) 400amp ATS and 100kw Kohler rapid response generator
>>>> 3) 20kw ground mount array with (2) SE Inverters located at the array.
>>>> Feeder from array is 1,000 ft to Service. Six years old and wiring is janky.
>>>> 4) Data logging for the last year shows peak demands of almost 40kw.
>>>> This could increase as several of formerly vacant  guest residences could
>>>> be occupied.
>>>>
>>>> My go to is almost always Schneider, however in this instance when I
>>>> looked into a quad stack, or more It seems like some type of controller is
>>>> needed to prevent imbalanced current passing through the relays during
>>>> transfer. That left me a bit concerned. Has anyone successfully stacked 4
>>>> or more XWPROs?
>>>>
>>>> Then there is the matter of AC or DC coupling? I really want no part in
>>>> having anything to do with SE. The inverters are already looking pretty
>>>> weathered taking the brunt of the prevailing winds and storms (they are
>>>> mounted to one of the ground mount poles). Seems like a great waste to pull
>>>> out the 4/0 feeders and replace strings. My other hesitancy with AC
>>>> coupling is that we would lose PV monitoring and control.
>>>>
>>>> I've also considered Sol Ark 15's, like three of them. We've got some
>>>> SA systems under are belt now and the only thing I can say that I like is
>>>> the speed of installation and the 200amp pass through. Other than that,
>>>> they leave me uninspired. One very large system continues to have glitches
>>>> that SA just shrugs their shoulders about. If we were to do three 15's, *what's
>>>> the preferred combining method?* All that I can come up with is a
>>>> custom 400a panelboard w/ three 200a breakers.
>>>>
>>>> Price is not a consideration for this project. The new owners of this
>>>> property (which is plagued with outages) have tasked me with building
>>>> something that is ultra reliable and good take over in a situation where
>>>> the grid is no longer available.
>>>>
>>>> Any suggestions or tips are appreciated.
>>>>
>>>> Michael
>>>>
>>>> --
>>>>
>>>> Michael Morningstar
>>>>
>>>>
>>>> Morningstar Electric
>>>>
>>>> PO Box 1494
>>>>
>>>> Mount Shasta, CA 96067
>>>>
>>>> 530-921-0560
>>>>
>>>> mjmorningstar at gmail.com
>>>>
>>>>
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>>
>> --
>>
>> Michael Morningstar
>>
>>
>> Morningstar Electric
>>
>> PO Box 1494
>>
>> Mount Shasta, CA 96067
>>
>> 530-921-0560
>>
>> mjmorningstar at gmail.com
>>
>>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>> Pay optional member dues here: http://re-wrenches.org
>>
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>
> --
>
> Michael Morningstar
>
>
> Morningstar Electric
>
> PO Box 1494
>
> Mount Shasta, CA 96067
>
> 530-921-0560
>
> mjmorningstar at gmail.com
>
>
>

-- 

Michael Morningstar

Morningstar Electric

PO Box 1494

Mount Shasta, CA 96067

530-921-0560

mjmorningstar at gmail.com
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