I may be missing something here...... but, for a manual switching solution, why not use two standard 600V DC discos. Put the PV to the top of both, load side of one goes to the battery inverter, load side of the other to the grid tied inverter. Turn one off, turn the other one on. Not as elegant as a transfer switch, maybe more expensive, but seems dirt simple and available now.
Dick Ratico Solarwind Electric --- You wrote: Could you use the old Dankoff trick of running through 2 poles in series of a 300 v rated switch? That used to be approved, before we had all these 600 v rated equipment. R. Walters r...@solarray.com Solar Engineer On Nov 7, 2011, at 1:16 PM, Larry Crutcher, Starlight Solar Power Systems wrote: > Ray, > Yes, the idea was for a low cost way to add battery backup to existing high voltage PV grid tie systems, not new construction. > > The second inverter does not need to be able to sell since that is handled by the grid tie inverter. It simple passes grid power to loads and maintains the battery. That means any off-grid inverter/charger or even low cost separate inverters and chargers may be used, a very economical solution. However, the idea may be of no value because it appears no one makes a transfer switch. > > Larry Crutcher > Starlight Solar Power Systems > > > > > On Nov 7, 2011, at 11:32 AM, Ray Walters wrote: > >> Just curious, what's the advantage of switching at the array vs. just using a Sunny Island or Outback system? Seems this would cost more, and have less efficiency, since you would still have the battery float losses, backup inverter idle losses, in addition to the 2nd grid tie inverter losses. Are there site specific conditions driving this that I'm not understanding? >> I've done quite a few GT systems w/ battery backup, so I'm always up for new ideas though. >> >> Ray >> >> >> On 11/7/2011 12:15 PM, Larry Crutcher, Starlight Solar Power Systems wrote: >>> >>> Hi Glen, >>> That model is a disconnect switch. What the system needs is a 4 pole transfer switch, automatic or manual, to connect the PV source to the charge controller. >>> >>> Hello Gary Willit, >>> Yes, you've grasped my concept precisely and I agree, getting a high voltage DC transfer switch may nix this design. Sounds like a product for Midnite Solar to build. >>> >>> >>> >>> Larry Crutcher >>> Starlight Solar Power Systems >>> >>> >>> On Nov 6, 2011, at 1:42 PM, Glenn Burt wrote: >>> >>>> Siemens makes a line that are UL listed. >>>> Their VBII series like HNF361PV - 30A >>>> >>>> -Glenn >>> --- end of quote --- _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
