The Radian is also the system that I would typically use in this situation. Although I am interested what people think about using a Sol-Ark inverter here. I have not used one yet, but I am interested in the fact that everything is integrated into one box, the string voltages can be up to 500V, and also if there is a battery failure at some point they can still run as a grid tied system. Cheers, Dave
*Dave Tedeyan, PE* Senior Engineer | Taitem Engineering, PC 110 South Albany Street | Ithaca, NY 14850 o. *607.277.1118 x121* f. 607.277.2119 www.taitem.com Solar • Sustainability • Energy • Design Certified B-Corporation since 2013 On Wed, Mar 3, 2021 at 7:10 AM John Blittersdorf < john.blittersd...@gmail.com> wrote: > William, > I agree with you with Radian, Fortress and just add a subpanel > identical to the main grid panel as close possible. Put all critical loads > on sub and larger loads on grid panel. Being side by side, swapping > circuits is easy. I also install an iota charger for generator redundancy. > OpticRE works great for monitoring. > > John Blittersdorf > > On Wed, Mar 3, 2021 at 1:19 AM William Miller <will...@millersolar.com> > wrote: > >> Friends: >> >> >> >> I am getting asked more often to provide design for grid-tied battery >> backup systems. I generally try to talk clients out of battery backup >> because I have always felt that the grid is the greenest battery and that >> the grid reliability is better than one might remember. However, with >> climate change and media attention, the need and market pressure is >> becoming stronger. >> >> >> >> I am really interested in what others have created in the way of >> solutions to this question. I have thought about it a lot. If its ok, I’d >> like to free-associate about some of my concerns and conclusions then ask >> if any of you are willing to share your ideas on how best to fill this >> need. Here goes: >> >> >> >> I am a firm believer in segregate load delivery for these reasons: >> >> 1. To back up an entire grid service you have to, in good conscience, >> perform a thorough load study and provide enough through-transfer to >> provide for maximum load conditions during grid up-time. The backup system >> cannot be a supply bottle-neck. >> >> 2. I don’t accept manual load-shedding for one moment. What if the AC >> and the dryer are running when the grid goes out? The system crashes. >> >> 3. In a home with whole-house backup, it is difficult for the consumer >> to know there is an outage and to conserve. Cellphone notification >> features are now more common, but cell phone batteries die and phones get >> left in the other room with the ringer off, so it is possible for >> homeowners to leave consumptive loads on after the grid goes down. >> >> >> >> Conclusion: With segregated loads, the transfer, inverter and storage >> can be scaled down and the reliability increases. Less cost, better >> performance. >> >> >> >> So given that the system sizing will be modest, has anyone come up with a >> reasonable design using standard, grid-sell capable battery inverters? >> >> >> >> Here is how I am imagining such a system: >> >> >> >> I see a modest battery system with a 4 to 8 KW inverter, DC coupled PV >> and a matching no-maintenance battery system. It would have these >> components: >> >> >> >> Inverter: Must have a dedicated generator and grid input and good remote >> monitoring, robust web interface and email notification. Outback Radian. >> >> >> >> Batteries: Gel or lithium. I have a client that has been grid-floating >> a set of MK Powered gel batteries since 1999. Or a Blue Planet or Fortress >> cabineted system. >> >> >> >> Generator: Small pad-mount natural gas or propane fueled generator or a >> portable gas powered unit with stabilized gas. If the generator is >> portable, provide an AC flanged inlet and sturdy cord long enough so >> generator can be 10 feet from any opening in the home. Provide durable >> signage on the generator indicating CO safety practices. >> >> >> >> PV: DC coupled for simplicity. Sized based on annual energy needs, not >> on critical loads. Grid power is likely to go down in the stormy winter >> months or smoky fire season, so PV is not a reliable energy source during >> grid outages. >> >> >> >> AC Distribution: Segregated loads with at least one commonly used >> lighting circuit not on the critical loads panel so the homeowner soon >> realizes the power is out. >> >> >> >> Unless you are a Tesla dealer, I am sure many of you have gone through >> the same mental acrobatics trying to figure out the best solution to this >> design request. I am very interested in what the rest of you may have come >> up with. >> >> >> >> Thanks in advance. >> >> >> >> William Miller >> >> >> >> Miller Solar >> >> 17395 Oak Road, Atascadero, CA 93422 >> <https://www.google.com/maps/search/17395+Oak+Road,+Atascadero,+CA+93422?entry=gmail&source=g> >> >> 805-438-5600 >> >> www.millersolar.com >> >> CA Lic. 773985 >> >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> 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 > > 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 > >
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