I'm not a fan of this strategy. What happens when the coil fails? It's not a failsafe solution IMO.
Jason Szumlanski On Tue, Jul 21, 2020 at 10:52 AM <drake.chamber...@redwoodalliance.org> wrote: > Larry, > > Connect the coil of a 240 VAC contactor to the output of the generator > circuit. Have the contacts of the relay break the AC coupled feed. > > Drake > --- > > > > On 2020-07-20 16:25, William Miller wrote: > > > > Larry: > > > > If you can automate disabling grid-sell when connected to the generator in > a fool proof manner then you may have a solution. If the system fails I > see a damaged generator but not a life-safety issue. > > > > William > > > > > > *From:* la...@starlightsolar.com [mailto:la...@starlightsolar.com] > *Sent:* Monday, July 20, 2020 1:19 PM > *To:* William Miller; RE-wrenches > *Subject:* Re: [RE-wrenches] Tesla Powerwall 2.0 - Experience?/Generator > charging > > > > Hi William, > > Thank you for your response. I was responding to the question of use off > grid and Hiltons question about generator use. Jason said, "But Tesla is > clear in that they do not allow a generator to interact with the Powerwall > in any way." This is true. > > > > Powerwall uses AC coupled inverters for off grid charging. If AC from the > micro-inverters was switched off and the generator provided the 240 Volt to > the Powerwal inverter inputl, would that not be a temporary solution to the > generator prohibition? The power wall would see incoming power and sync. Of > course, the system *must* be monitored. If the power wall calls for > cutback or disconnect by raising frequency, the generator should be > disconnected, if it indeed works like that. If Powerwall provides an > internal disconnect, then it would be safer for the user. Just trying to > think outside the box. > > > Larry Crutcher > Starlight Solar Power Systems > > > > > > On Jul 20, 2020, at 12:01 PM, William Miller <will...@millersolar.com> > wrote: > > Larry: > > I am not Tesla conversant but allow me to speculate: If any grid-tied > system can be fed from a generator it could also feed back to the > generator, which may damage said generator. The grid-tied system should > therefore be connected upstream of any transfer switching, making it > ineligible to be charged from the generator. > > William > > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On > Behalf Of la...@starlightsolar.com > Sent: Monday, July 20, 2020 10:52 AM > To: RE-wrenches > Subject: Re: [RE-wrenches] Tesla Powerwall 2.0 - Experience? > > Since the Powerwall is AC coupled, how will it know if the power source is > a PV solar array or a generator if either feed the PV input? It seems > simple AC switching is all that would be needed. I like to think outside > the box but I'm not familiar with Powerwall. > > Larry Crutcher > Starlight Solar Power Systems > > > > On Jul 20, 2020, at 9:53 AM, Jason Szumlanski < > ja...@floridasolardesigngroup.com> wrote: > > The Powerwall 2 is now supported by Tesla in an off-grid configuration > from what I heard. It is AC coupled. It cannot interact with generators > whatsoever. You can't charge the battery with a generator and you can't AC > couple a generator to it. If you want a generator, you put a transfer > switch on the load side of the gateway device. If the battery dies, > the generator starts. The generator powers loads, but does not recharge the > battery because it becomes isolated via the transfer switch. The big > downside I see with that is there would be a loss of power to the loads > until the generator fires up. I don't see a way around that. > > I'm not a Tesla certified installer, but I have seen some of these > batteries out in the wild and that's just the way it is - it's an > integrated unit. I'd call it an "AC Battery," kind of like an AC PV Module. > To answer another point in this thread, if the battery reaches its LBCO it > can only recharge with PV in an off-grid scenario. It reserves battery > capacity to turn on occasionally to see if there is PV input. At least > that's how I understand it to work. I don't know what would happen if the > battery actually reached 0%. Seems risky. I'm not sure how you would "jump > start" it. Publicly available details seem scant on this, but there are a > few system owners talking about it if you dig deep on the Interwebs. > > It will be interesting to see what Enphase comes up with. There are > generator inputs on their Ensemble system, but no software support for this > yet. The concept is very similar to Tesla in that there is a gateway > device, essentially a transfer switch with battery controls inside. The > Gateway acts as the AC point of coupling for everything to tie in together. > > I'm not sure why you couldn't use a generator to charge the Powerwall > battery the same way you would charge with the grid. However, you would > need a way to disable PV AC coupling when the generator is running. I can > see how Enphase would be able to do this pretty easily. But Tesla is clear > in that they do not allow a generator to interact with the Powerwall in any > way. > > Jason Szumlanski > > > On Sun, Jul 19, 2020 at 11:43 AM Hilton Dier III <hiltond...@gmail.com> > wrote: > > Greetings, Wrenches, > I have an off-grid client who has been reading the buzz about the Tesla > Powerwall 2.0. I have been reading the data sheets and manual for it and it > appears to be AC coupled only. There was talk of a DC input version, but > apparently that fell by the wayside. I try to be agnostic about technology, > and I'd be willing to subcontract a Tesla-approved installer if, in fact, > this was the best solution. > Does anybody have experience using the Powerwall 2.0 in an off grid PV > system? Is it AC coupled only? 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