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
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