[RE-wrenches] 120 Vac and 12Vdc mixed distribution system

Thu Apr 25 07:33:49 PDT 2024

I had a lot of trouble keeping QO breakers functional on a 12VDC
distribution system. I'd have to move them around every week or so to keep
a good contact on the plug in contacts. They seem to work fine on a 24VDC
system. I went to using MNPV or MNDC breakers instead in PV combiner or
other MidNite boxes. QOU breakers are fine, but I don't know of any
standard distribution box for them.

Brad Bassett
Application Engineer retired

On Wed, Apr 24, 2024 at 11:42 AM Jason Szumlanski via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi Dave,
>
> I appreciate the concern. It's not one of those situations. We have a
> couple of barrier islands around here where people have set up what amounts
> to little fish camps that are used infrequently. The islands are also home
> to a few full-time/most-time residents and state parks. Everyone knows
> everyone. The clients are safe and reliable. These sites range from places
> that people paid just tens of thousands of dollars decades ago all the way
> up to many-multi-million dollar strips of sand where very wealthy people
> like to look out over Naples beach a couple times of year from their
> off-grid mansions. It's pretty interesting.
>
> I "get" why people who only take friends out a few times a year on a
> fishing expedition want a band-aid approach. There is no reason to throw
> $100K at a situation like this. In this case, I feel I can get creative to
> meet the very limited 12V and 120V needs while providing a reliable and
> long-lasting solution for around $25K and pocket enough money that I want
> to answer their call in the future. Right now they are getting by with 4 x
> 100W Solarland modules with a 9.6kWh battery bank and a Honda EU2000. I'm
> certain they will be blown away with the performance of whatever I propose,
> and happy that it is installed in a safe and professional manner.
>
> The current distribution systems look solid, each protected by a Square D
> QO breaker panel and professionally installed. The power production and
> delivery system is a total kludge that I feel I can fix without too much
> risk.
>
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
> Florida Certified Electrical Contractor EC13013208
>
>
> On Wed, Apr 24, 2024 at 2:19 PM Dave Angelini Offgrid Solar via
> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>
>> How about just buy an RV?
>>
>> Seriously the reason Jason I am Leary is because of the experiences I
>> have had with what I call Offgrid Squalor.
>>
>> Just have to be careful especially these days of druggies, people in vans
>> with no windows, ex paramilitary that went bad,
>> and you get the picture.
>>
>> If you know the person that is the way to keep you and your loved ones
>> safe. Money does talk sometimes and the lack can of it
>> can be a warning.
>>
>> Also as mentioned, these types of situations, are what gets my accountant
>> telling me if you do not charge enough,
>> no one will listen to your advice.
>>
>>
>>
>> *Dave Angelini Offgrid Solar
>> "we go where powerlines don't"
>>    <http://members.sti.net/offgridsolar/>https://offgridsolar1.com/ <https://offgridsolar1.com/>  <http://members.sti.net/offgridsolar/>
>> e-mail  offgridsolar at sti.net <offgridsolar at sti.net>
>> text 209 813 0060*
>>
>>
>> On 2024-04-24 10:51 am, John Blittersdorf via RE-wrenches wrote:
>>
>> Jason,
>>   Just using the converter works fine. They are considered a battery
>> charger or a regulated power supply. I am currently running that way now
>> with the battery cables going nowhere.  I was thinking of putting the
>> battery back in the system just for triple redundancy when my inverter hits
>> low battery cutoff voltage on a cold winter night and no fuel for the
>> generator (or it won't start).
>> My Iota DLS puts out a regulated 13.4 volts up to 30 amps.
>>
>> John
>>
>> On Wed, Apr 24, 2024 at 8:25 AM Jason Szumlanski via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Ah ha! I didn't consider using a small 12V battery with a charger. I was
>> thinking of just using a 120V -> 12V converter to handle the DC loads. Is
>> the 12V battery really necessary, or can I just power the DC loads directly
>> with a converter? If I just have lights and fans on the DC system, the load
>> should be pretty minimal.
>>
>> I could use a separate 12V battery, but I would like to eliminate that
>> cost and complexity if possible.
>>
>>
>> And yeah, I am not considering this a money making opportunity. It's
>> really just a challenge to ward off boredom from the daily grind.
>>
>> Jason Szumlanski
>> Principal Solar Designer | Florida Solar Design Group
>> NABCEP Certified Solar Professional (PVIP)
>> Florida State Certified Solar Contractor CVC56956
>> Florida Certified Electrical Contractor EC13013208
>>
>> On Wed, Apr 24, 2024 at 8:01 AM John Blittersdorf via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Jason,
>>   I have a customer with the same situation except he already has a 12 V
>> VFX inverter,  He has a sunfrost fridge and other small loads with a very
>> fancy custom control board
>> originally set up to handle AC and DC systems.  We are adding a lot more
>> solar and I was considering a dual battery system but the owner didn't like
>> that idea.  We are going with and Iota 12v power supply (i use one at my
>> house for my sunfrost) to power up all his DC loads and will be adding a
>> large 48 V battery bank and over 4Kw of solar using a VFXR3648 directly in
>> place of the 12V inverter.  He complained that the existing inverter would
>> not handle all his current AC loads very well.  My own house is fully wired
>> for 12VDC as well as AC (lots of #10 copper not being used) and I have been
>> considering getting a small LFP 12V battery to put back on by DC System.
>> Then use the Iota as a secondary charging method with some of my large
>> stash of older modules hooked up for 12V direct with C40 charge controller
>> to recreate my original system just for kicks. I'm only using DC for my
>> Sunfrost and one "emergency light" in the livingroom right now.  For your
>> customer, a small LFP 12v battery (approximately $500 or less) to replace
>> his old battery bankm and more larger ones for the new AC side with 48V
>> inverter fed by his generator or through an Iota 48 V charger ifusing a
>> smaller non charging inverter. Unlike Dave, I like these challenges. Maybe
>> thats why I never seem to make money.!!
>>
>> John Blittersdorf
>> offgridvermont.com
>>
>>
>> On Wed, Apr 24, 2024 at 7:22 AM Jason Szumlanski via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Fortunately, the owner is pretty handy and is willing to live with any
>> negative consequences. That said, I want to offer him something as simple
>> and bulletproof as possible. I am walking into this with eyes wide open,
>> for sure.
>>
>> Jason Szumlanski
>> Principal Solar Designer | Florida Solar Design Group
>> NABCEP Certified Solar Professional (PVIP)
>> Florida State Certified Solar Contractor CVC56956
>> Florida Certified Electrical Contractor EC13013208
>>
>> On Tue, Apr 23, 2024 at 5:47 PM Dave Angelini Offgrid Solar via
>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Not being helpful but I  walk away from these.  It will come back to you.
>>
>> *Dave Angelini Offgrid Solar
>> "we go where powerlines don't"
>>    <http://members.sti.net/offgridsolar/>https://offgridsolar1.com/ <https://offgridsolar1.com/>  <http://members.sti.net/offgridsolar/>
>> e-mail  offgridsolar at sti.net <offgridsolar at sti.net>
>> text 209 813 0060*
>>
>>
>> On 2024-04-23 2:40 pm, Jason Szumlanski via RE-wrenches wrote:
>>
>> I have an off-grid client who is working on replacing old equipment at a
>> cabin. He has a lot of 12 volt distribution in the house for lighting,
>> fans, and a 12 volt refrigerator. He also has 120 volt AC loads that run
>> through a separate distribution panel where the only source is a 2000 Watt
>> Honda generator. There is no inverter present. The batteries are charged
>> through a Trace C40.
>>
>> He currently has a few ancient solar panels and a struggling Bank of AGM
>> batteries. It's time for an upgrade. I can easily supply enough PV power
>> for what he needs. He currently has a 9 kilowatt hour battery capacity that
>> he was happy with when the batteries operated optimally. Nonetheless, I
>> would probably future-proof him with a 10 to 15 kilowatt hour LiPo to
>> double or triple his usable capacity.
>>
>> For convenience, obviously it would be nice to have an inverter to
>> eliminate or reduce the generator requirement. But he seems committed to
>> keeping his 12 volt distribution because it would be costly to replace
>> fixtures. I think he would consider replacing the 12 volt refrigerator if
>> he has an inverter.
>>
>> He definitely wants LiPo batteries.
>>
>> I don't like the idea of 12 volt direct from a battery plus connecting an
>> inverter to that same battery. It is going to be hard to measure and
>> monitor things.
>>
>> I am thinking about using a 48 volt battery with a single phase 120 volt
>> inverter, getting him to change to a 120 volt refrigerator, and using a DC
>> converter to give him somewhere in the range of 100 amps at 12 volts for
>> his existing DC lighting and fan loads. Is this a bad idea? Should I stick
>> with a 12 volt battery system? He does have a tiny 12 volt pressure pump
>> which might be an issue for the converter. I'm not sure. I am a bit worried
>> about the efficiency loss and capacity of DC converters and not sure how to
>> size it.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
>>
>>
>>
>>
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