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

Wed Apr 24 11:41:57 PDT 2024

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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