Going to install a solar system at a future date. Need to upgrade the existing 45 year old 200 amp Zinsco MSP first and decide on the new MSP breaker sizes.
The planned 6kw solar system would have two 8 panel arrays and one string inverter, SMA Sunny Boy 6000TL-US with a 25 amp max a/c output, connected to a subpanel in the garage. Their is already a 125 amp subpanel that has 90 amps of total breakers installed (3 20's, 2 15's,) and is serviced by the MSP with a 50 amp breaker. The wiring to the subpanel appears to be 8 awg with ~30 foot run.
Given the below calcs, the 125 SP would need to be upgraded. If the SP is upgraded to 200 amps, can a 50 amp MSP breaker service it with the additional inverter? The existing 50 amp breaker has never tripped in 15 years. Then again, it is an older Zinsco breaker that was installed about 25 years ago when the garage was built. The garage 125 amp SP services 40 amps to a water well pump, garage lights, door opener and some outlets. No welding or heavy duty shop equipment in garage.
120 rule for a 125 amp subpanel: 125 x 1.2 = 150 - 50 (50 amp MSP breaker) = 100 breaker amps available.
120 rule for a 200 amp subpanel: 200 x 1.2 = 240 - 50 (50 amp MSP breaker) = 190 breaker amps available
Any ideas or suggestions appreciated.
The planned 6kw solar system would have two 8 panel arrays and one string inverter, SMA Sunny Boy 6000TL-US with a 25 amp max a/c output, connected to a subpanel in the garage. Their is already a 125 amp subpanel that has 90 amps of total breakers installed (3 20's, 2 15's,) and is serviced by the MSP with a 50 amp breaker. The wiring to the subpanel appears to be 8 awg with ~30 foot run.
Given the below calcs, the 125 SP would need to be upgraded. If the SP is upgraded to 200 amps, can a 50 amp MSP breaker service it with the additional inverter? The existing 50 amp breaker has never tripped in 15 years. Then again, it is an older Zinsco breaker that was installed about 25 years ago when the garage was built. The garage 125 amp SP services 40 amps to a water well pump, garage lights, door opener and some outlets. No welding or heavy duty shop equipment in garage.
120 rule for a 125 amp subpanel: 125 x 1.2 = 150 - 50 (50 amp MSP breaker) = 100 breaker amps available.
120 rule for a 200 amp subpanel: 200 x 1.2 = 240 - 50 (50 amp MSP breaker) = 190 breaker amps available
Any ideas or suggestions appreciated.
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