Jason, My vote would be for using a 120 to 12vDC power supply large enough to handle the remaining 12 vDC loads and skip the second battery bank. In my mind, this is simpler, cleaner, and if the power supply fails at some point, it is an easy replacement, if they still want to keep the DC loads then. Easier maintenance and operation for the client, less headache for you. I've definitely gravitated toward the KISS concept of the years, for both my and my clients' sanity...
Howie Michaelson Sun Catcher On Wed, Apr 24, 2024 at 8:26 AM Jason Szumlanski via RE-wrenches < re-wrenches@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@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@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@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 offgridso...@sti.net <offgridso...@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 >>>> >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> List sponsored by Redwood Alliance >>>> >>>> Pay optional member dues here: http://re-wrenches.org >>>> >>>> List Address: RE-wrenches@lists.re-wrenches.org >>>> >>>> Change listserver email address & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> There are two list archives for searching. When one doesn't work, try >>>> the other: >>>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> >>>> List rules & etiquette: >>>> http://www.re-wrenches.org/etiquette.htm >>>> >>>> Check out or update participant bios: >>>> http://www.members.re-wrenches.org >>>> >>>> _______________________________________________ >>>> List sponsored by Redwood Alliance >>>> >>>> Pay optional member dues here: http://re-wrenches.org >>>> >>>> List Address: RE-wrenches@lists.re-wrenches.org >>>> >>>> Change listserver email address & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> There are two list archives for searching. When one doesn't work, try >>>> the other: >>>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> >>>> List rules & etiquette: >>>> http://www.re-wrenches.org/etiquette.htm >>>> >>>> Check out or update participant bios: >>>> http://www.members.re-wrenches.org >>>> >>>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> Pay optional member dues here: http://re-wrenches.org >>> >>> List Address: RE-wrenches@lists.re-wrenches.org >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> There are two list archives for searching. When one doesn't work, try >>> the other: >>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> http://www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> http://www.members.re-wrenches.org >>> >>> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. 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