Main Panel Question

[Cacao]

My question is regarding the power flow/distribution in the main panel when solar system is integrated. My specific case is a hybrid system, but the question also applies to the tie-ins:

When the PV electricity after inverter, break switches, etc., ultimately enters the main panel, it does so through a regular breaker of XX Amps and 1 or 2 poles (call it “solar breaker”). That creates a situation where the input transmission can take place from the grid via the main switch or the solar breaker or both.

My question is, what controls where the load circuits in the main panel get their feed: the grid vs solar. It seems that both supplying current would create a real problem in the panel.

So, is it some sort of a hook up to the smart/2 way meter or is there circuit device I am missing and ought to be aware of?

 

[SolarScott]

My question is regarding the power flow/distribution in the main panel when solar system is integrated. My specific case is a hybrid system, but the question also applies to the tie-ins:

When the PV electricity after inverter, break switches, etc., ultimately enters the main panel, it does so through a regular breaker of XX Amps and 1 or 2 poles (call it “solar breaker”). That creates a situation where the input transmission can take place from the grid via the main switch or the solar breaker or both.

My question is, what controls where the load circuits in the main panel get their feed: the grid vs solar. It seems that both supplying current would create a real problem in the panel.

So, is it some sort of a hook up to the smart/2 way meter or is there circuit device I am missing and ought to be aware of?

I use a generator interlock device. It only allows one or the other to feed power in, not both.

 

[a619]

Grid supplies what your load demands. In an AC coupled system, your PV breaker is already back feeding power that can be used by your home loads, and hence the requirement for power draw from grid is less. There’s nowhere for PV power to go except your home loads or back to grid if your loads cannot use that.
In a DC coupled system, inverter only draws enough power from PV to cover load demand. If demand is higher, it draws additional power from grid.

 

[Shimmy]

(NEC) Code requires the bus for that main panel to be sized appropriately to handle both the utility current limited by the main and the solar current limited by the inverter. You can design based on 120% of the bus rating being greater than the sum of hte other two.

 

[Cacao]

Grid supplies what your load demands. In an AC coupled system, your PV breaker is already back feeding power that can be used by your home loads, and hence the requirement for power draw from grid is less. There’s nowhere for PV power to go except your home loads or back to grid if your loads cannot use that.
In a DC coupled system, inverter only draws enough power from PV to cover load demand. If demand is higher, it draws additional power from grid.

Thank you! This answer makes a lot of sense to me. So much so, that it is obvious in hindsight! I should've been able to figure that out myself, but couldn't.
Thanks again for taking the time.

 

[summit]

only works if it's a grid-tie inverter, not an off-grid inverter. A grid-tie inverter would match up with grid's frequency, etc....

 

[PR-Solar]

only works if it's a grid-tie inverter, not an off-grid inverter. A grid-tie inverter would match up with grid's frequency, etc....

"My specific case is a hybrid system, but the question also applies to the tie-ins:"
The inverter would be a hybrid inverter, as stated.

 

[summit]

My question is regarding the power flow/distribution in the main panel when solar system is integrated. My specific case is a hybrid system, but the question also applies to the tie-ins:

When the PV electricity after inverter, break switches, etc., ultimately enters the main panel, it does so through a regular breaker of XX Amps and 1 or 2 poles (call it “solar breaker”). That creates a situation where the input transmission can take place from the grid via the main switch or the solar breaker or both.

My question is, what controls where the load circuits in the main panel get their feed: the grid vs solar. It seems that both supplying current would create a real problem in the panel.

Is your "hybrid" inverter a grid-tie then ? if not, smoke alert

 

[PR-Solar]

Is your "hybrid" inverter a grid-tie then ? if not, smoke alert

my hybrid inverter is a hybrid inverter

EG4 18KPV Hybrid Inverter | All-In-One Solar Inverter | 18000W PV Input | 12000W Output | 48V 120/240V Split Phase | EG4 18KPV-12LV

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

it is not a true grid-tie because it - let's see if i get the jargon right here - "has ac coupling" which allows automatic shut off from the grid loaprovide power to the loads during a black out events among other things.
a true tie-in would need a lot of manual finagling to allow that afaiu.

 

[summit]

quite a hefty inverter, but don't think it's a grid-tie. Haven't read the manual but from the fancy brochure info at signarture, the output is meant to power a separate critical-load sub-panel, not to the main panel. When grid is on, the inverter by-passes grid to the sub-panel. It'll charge its battery until full but then does not augment the house load. Upon black out, the inverter continues to power the sub-panel from solar and battery as needed.

This is my understanding of a hybrid inverter, but can be incorrect.

 

[Jim in Florida]

The 18Kpv Hybrid inverter is capable of grid tie with an automatic switching. It is capable of off grid mode also.