[RE-wrenches] High Voltage MPPT units

[Larry Crutcher, Starlight Solar Power Systems]

Dick,
I had that thought as well but it leaves open the possibility of paralleling the grid inverter and charge controller. What effect that will have is yet to be explored.

This idea originated for my personal residence in Yuma which has 4400 watts of PV. We leave that home for several months in the summer but want to protect our frozen foods from power outage after having lost big $$ in ruined food. So I could employ the double disconnect if the AHJ will accept it but I have high reservations in selling that method to others.

Larry Crutcher
Starlight Solar Power Systems

On Nov 8, 2011, at 5:34 AM, Richard L Ratico wrote:

> 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
> ray at 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