My hunch is that the anti-islanding in the grid tie inverter is going to push the little battery inverter out of spec, even with a diversion load, and they will never connect. But I'd be very interested to see if that is so if someone tries it.
Brad AEE Solar On Wed, Mar 4, 2020 at 4:08 PM Kienan Maxfield <maxfieldso...@hotmail.com> wrote: > Mark, > > Sorry, I just barely joined the conversation... This is an interesting > idea/project. You have a couple of obstacles... The first and biggest one > is what Don said... unless you have a relatively rare 120V PV inverter, > you're going to need 240 to the PV inverter. Now, this could be > accomplished with a balancing transformer or a 2:1 transformer. > > Now any battery-based inverter *can* be AC coupled, but if (as in this > case) it's not rated for AC coupling, then it doesn't have the controls to > protect itself or the battery. The PLC that monitors the battery voltage > and runs the diversion load should work fine for protecting the batteries > (so long as the water in the electric heater doesn't boil away, and there's > no thermostat to turn off the diversion load). The only missing link is > protecting the battery inverter. This inverter is only rated to pass 500W > through, but if the battery is really low, and then the sun comes out, the > PV inverter may try to push 2kW through the inverter into the battery. > Since the battery is really low, your PLC won't activate the diversion > controller in time. This could potentially fry the inverter. > > Now, perhaps, in addition to monitoring the battery voltage, if your PLC > was also monitoring the current going into the inverter on the AC outputs, > then your PLC could activate the diversion load in order to prevent more > than perhaps 300W from back-feeding into the inverter (to give you a safety > margin). Assuming that the PLC works correctly and never has any bugs, then > this should work out just fine. > > Thanks, > Kienan > > *Maxfield Solar* > *maxfieldso...@hotmail.com* <maxfieldso...@hotmail.com> > * (801) 631-5584 (Cell) * > ------------------------------ > *From:* RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> on behalf > of Jay <jay.pe...@gmail.com> > *Sent:* Wednesday, March 4, 2020 11:59 AM > *To:* RE-wrenches <re-wrenches@lists.re-wrenches.org> > *Subject:* Re: [RE-wrenches] OK, so what would happen if I do this... > > I’m not sure I agree. The battery charger is just another load to his > other loads. > They will cycle on and off. > > The whole design is sort of cobbled. I’m guessing that John is looking for > a fun project. > > Jay > > On Mar 4, 2020, at 10:21 AM, Kent Osterberg <k...@coveoregon.com> wrote: > > Jay, > > My point is that even if the diversion load can handle all of the watts > and the PLC is fast enough to react to changes in the ac voltage, the > system will probably still be unstable because the battery charger is in > the control loop. > > Kent Osterberg > Blue Mountain Solar > > > > On 3/4/2020 9:25 AM, Jay wrote: > > Hi Kent, > > Johns diversion load/controller would take have to take care of watts and > ac voltage parameters. > > > > Jay > > > > On Mar 4, 2020, at 9:00 AM, Kent Osterberg <k...@coveoregon.com> > <k...@coveoregon.com> wrote: > > If using an ac battery charger to get power around the inverter to the > batteries it would have to be rated for the full power of the PV array. > Otherwise, you couldn't divert the full power of the array on the dc side. > For a 24-volt battery, it would require a battery charger rated for over 80 > amps. That alone seems risky with a 100Ah battery. To add to the difficulty > of this approach the battery charger would add a delay time in the control > loop that would almost certainly result in an unstable system. > > Kent Osterberg > > > On 3/3/2020 7:53 PM, Jay wrote: > > Or a charger such as Iota, or power max. > > Jay > Peltz power. > > On Mar 3, 2020, at 7:24 PM, d...@energysolarnow.com wrote: > > > You wrote that you would connect the Exeltech to just one of the service > phases. > But most GT inverters are 240 and require both phases. Is yours different? > You did not mention which model it is. > Also, as Kent Osterberg mentioned, the Exeltech will not charge its > batteries from the AC output. > Your scheme with the PLC controlling an SCR leaves unaddressed how any > charge current gets directed into the batteries to allegedly raise their > voltage. Is there a charger somewhere in this scheme? > You still need some way to charge batteries from solar. How about > connecting a charge controller to some of the solar panels? > > Don Barch > Energy Solar > > -------- Original Message -------- > Subject: RE-wrenches Digest, Vol 13, Issue 59 > From: re-wrenches-requ...@lists.re-wrenches.org > Date: Sun, March 01, 2020 2:19 pm > To: re-wrenches@lists.re-wrenches.org > > Send RE-wrenches mailing list submissions to > re-wrenches@lists.re-wrenches.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org > or, via email, send a message with subject or body 'help' to > re-wrenches-requ...@lists.re-wrenches.org > > You can reach the person managing the list at > re-wrenches-ow...@lists.re-wrenches.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of RE-wrenches digest..." > > > When responding to posts within the Digest, be sure to restore the > Subject: line to the original, and please edit out any extraneous lines > from the quoted message. > > > Today's Topics: > > 1. OK, so what iwould happen if I do this... (Mark Frye) > 2. Re: OK, so what iwould happen if I do this... (frenergy) > 3. Re: OK, so what iwould happen if I do this... (Kent Osterberg) > 4. Re: OK, so what iwould happen if I do this... (Jerry Shafer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 29 Feb 2020 15:27:32 -0800 > From: Mark Frye <ma...@berkeleysolar.com> > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Subject: [RE-wrenches] OK, so what iwould happen if I do this... > Message-ID: <93731c38-40b5-7c63-1d74-a879fbdd9...@berkeleysolar.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > I have 2kw of grid tied PV on my house. > > Suppose I: > > - Open the main breaker to disconnect from the grid > > - I open the PV breaker > > - I connect a small good quality inverter like an Exeltech XP 500 to one > of the phases of the service (120 VAC) > > - I put a small battery pack, 100 AH at 24 VDC on the inverter > > OK so far, I could run some small loads for a relatively short period of > time before the batteries get low > > -I have a PLC with an AD input and DA output. On the input I measure the > battery voltage, on the output I control a SCR. The SCR controls a 2kw > immersion heater sitting in a big bucket of water. The PLC has a scan > time of 2 mS and I program it to increase the duty cycle of the SCR as > voltage of the battery rises above 24 VDC. > > OK so far nothing has really changed from above. > > - I close the PV breaker, the GT inverters see the battery inverter, > sync and connect after five minutes. > > Voila, I can run house loads from 0 to 2kw with my existing GT PV with > the balance of energy dumped as needed to the immersion heater. > > Right? > > Mark Frye > > > > ------------------------------ > > Message: 2 > Date: Sun, 1 Mar 2020 06:26:27 -0800 > From: frenergy <frene...@psln.com> > To: re-wrenches@lists.re-wrenches.org > Subject: Re: [RE-wrenches] OK, so what iwould happen if I do this... > Message-ID: <c97234cd-4441-34d7-740c-51f07837b...@psln.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Mark, > > ??? ??? ??? OR, you change-out your inverter to an SMA with Secure > Power Supply and during grid power outage, while there is some sun on > the panels, you would have up to 2KW of 120VAC power on the SPS circuit > by just flipping a switch. We usually install a 4X outdoor box with a > 120 VAC outlet ganged with a switch right under the inverter and let the > customer run the power to the : frig, lights, battery charger, TV or > whatever during an outage, though some romex could be run to close to > the frig. > > Bill > > Feather River Solar Electric > Bill Battagin, Owner > 4291 Nelson St. > Taylorsville, CA 95983 > 530.284.7849 > CA Lic 874049 > www.frenergy.net > > On 2/29/2020 3:27 PM, Mark Frye wrote: > > I have 2kw of grid tied PV on my house. > > > > Suppose I: > > > > - Open the main breaker to disconnect from the grid > > > > - I open the PV breaker > > > > - I connect a small good quality inverter like an Exeltech XP 500 to > > one of the phases of the service (120 VAC) > > > > - I put a small battery pack, 100 AH at 24 VDC on the inverter > > > > OK so far, I could run some small loads for a relatively short period > > of time before the batteries get low > > > > -I have a PLC with an AD input and DA output. On the input I measure > > the battery voltage, on the output I control a SCR. The SCR controls a > > 2kw immersion heater sitting in a big bucket of water. The PLC has a > > scan time of 2 mS and I program it to increase the duty cycle of the > > SCR as voltage of the battery rises above 24 VDC. > > > > OK so far nothing has really changed from above. > > > > - I close the PV breaker, the GT inverters see the battery inverter, > > sync and connect after five minutes. > > > > Voila, I can run house loads from 0 to 2kw with my existing GT PV with > > the balance of energy dumped as needed to the immersion heater. > > > > Right? > > > > Mark Frye > > > > _______________________________________________ > > 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 > > > > List-Archive: > > > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > > > List rules & etiquette: > > www.re-wrenches.org/etiquette.htm > > > > Check out or update participant bios: > > www.members.re-wrenches.org > > > > > -- > > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > > > > ------------------------------ > > Message: 3 > Date: Sun, 1 Mar 2020 08:58:45 -0800 > From: Kent Osterberg <k...@coveoregon.com> > To: re-wrenches@lists.re-wrenches.org > Subject: Re: [RE-wrenches] OK, so what iwould happen if I do this... > Message-ID: <9e32901e-c5d4-ff70-9c44-406cc6d48...@coveoregon.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Mark, > > I believe that your plan would fail because you are forcing power to > flow through the XP inverter backwards to charge the batteries. I don't > believe the XP inverter can do that. The grid tied inverter would > probably connect then immediately shut down, or connect and immediately > ruin the XP inverter. It would work if you had a inverter with a > bidirectional architecture like a Magnum, Outback, or Schneider > inverter. But even then you'd have a hazardous situation because the > cooling water is going to evaporate. > > Kent Osterberg > Blue Mountain Solar > > > On 2/29/2020 3:27 PM, Mark Frye wrote: > > I have 2kw of grid tied PV on my house. > > > > Suppose I: > > > > - Open the main breaker to disconnect from the grid > > > > - I open the PV breaker > > > > - I connect a small good quality inverter like an Exeltech XP 500 to > > one of the phases of the service (120 VAC) > > > > - I put a small battery pack, 100 AH at 24 VDC on the inverter > > > > OK so far, I could run some small loads for a relatively short period > > of time before the batteries get low > > > > -I have a PLC with an AD input and DA output. On the input I measure > > the battery voltage, on the output I control a SCR. The SCR controls a > > 2kw immersion heater sitting in a big bucket of water. The PLC has a > > scan time of 2 mS and I program it to increase the duty cycle of the > > SCR as voltage of the battery rises above 24 VDC. > > > > OK so far nothing has really changed from above. > > > > - I close the PV breaker, the GT inverters see the battery inverter, > > sync and connect after five minutes. > > > > Voila, I can run house loads from 0 to 2kw with my existing GT PV with > > the balance of energy dumped as needed to the immersion heater. > > > > Right? > > > > Mark Frye > > > > _______________________________________________ > > 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 > > > > List-Archive: > > > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > > > List rules & etiquette: > > www.re-wrenches.org/etiquette.htm > > > > Check out or update participant bios: > > www.members.re-wrenches.org > > > > > > > > ------------------------------ > > Message: 4 > Date: Sun, 1 Mar 2020 07:31:36 -1000 > From: Jerry Shafer <jerrysgarag...@gmail.com> > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Subject: Re: [RE-wrenches] OK, so what iwould happen if I do this... > Message-ID: > <camufgmvybnmmzge__tjds9xpfsou59jdf3wwskfhjw291vg...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Mark > What you are saying is to AC couple but most likely this would fail as your > battery fills not enough loads HBCO or to much loads and your battery does > a LBCO, either way you would be better off spending the money in a maybe a > Outback Skybox easy install and is high voltage PV input and even a small > 48 volt bank but think about storage > Jerry > > On Sat, Feb 29, 2020 at 1:27 PM Mark Frye <ma...@berkeleysolar.com> wrote: > > > I have 2kw of grid tied PV on my house. > > > > Suppose I: > > > > - Open the main breaker to disconnect from the grid > > > > - I open the PV breaker > > > > - I connect a small good quality inverter like an Exeltech XP 500 to one > > of the phases of the service (120 VAC) > > > > - I put a small battery pack, 100 AH at 24 VDC on the inverter > > > > OK so far, I could run some small loads for a relatively short period of > > time before the batteries get low > > > > -I have a PLC with an AD input and DA output. On the input I measure the > > battery voltage, on the output I control a SCR. The SCR controls a 2kw > > immersion heater sitting in a big bucket of water. The PLC has a scan > > time of 2 mS and I program it to increase the duty cycle of the SCR as > > voltage of the battery rises above 24 VDC. > > > > OK so far nothing has really changed from above. > > > > - I close the PV breaker, the GT inverters see the battery inverter, > > sync and connect after five minutes. > > > > Voila, I can run house loads from 0 to 2kw with my existing GT PV with > > the balance of energy dumped as needed to the immersion heater. > > > > Right? > > > > Mark Frye > > > > _______________________________________________ > > 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 > > > > List-Archive: > > > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > > > List rules & etiquette: > > www.re-wrenches.org/etiquette.htm > > > > Check out or update participant bios: > > www.members.re-wrenches.org > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20200301/a993182d/attachment-0001.html > > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > 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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > ------------------------------ > > End of RE-wrenches Digest, Vol 13, Issue 59 > ******************************************* > > _______________________________________________ > 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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > 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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > 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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > 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 > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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