Connecting Solar into Home wiring, where at, and how??

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Beachnut
Beachnut Registered Users Posts: 3
in General Solar Power Topics #1
Hello All!:cool:

First time here, and posting!

I just received my initial design diagram from my solar installer. They are proposing to:

"TAP SYSTEM VIA INSULATION PIERCING ON LOAD SIDE OF MAIN BREAKER IN MAIN PANEL ENCLOSURE. CONDUCTORS ARE FIELD INSTALLED."

So they look to run the power from the inverter in at the outside utility meter / main 200 A breaker box, taping in just below the 200 A breaker on the load side. (Per diagram schematic and above). They also look to install everything (inverter, meter, shut off switch and fuse), on the outside of the house wall, and run conduit, looping over my eve, down to it from the panels on the roof. Which I requested they not do in the bidding process. I have a rope installed from the attic space directly below the solar panel roof area, clear through to my basement sub panel for them to use to pull flex conduit in with. I am hoping this was just a miss communication from the site inspector, to the designer...

Question for those in the know of electrical code: Do they have to tap in their below the 200 A breaker in my outside meter box? My sub panel is located less than 2' away from the outside meter / main breaker box, but located INSIDE my basement and protected. Can they "tap in" either on the load side of the incoming cable to the sub panel,, or, better yet, through a breaker IN the sub panel as there is space for many more breakers in my sub panel box.

I desire to have all the equipment mounted in my basement, on a false wood panel interior wall, right next to the sub panel, that is like less than 2' below the outside main utility meter / breaker for the home. There is 6-8" of dead space between this interior false wood panel wall, and the sub panel mounted between exposed studs, and fully accessible through a door on this "false wood panel wall" that hides all of the sub panel, studs, and mess. (Easy to drill through, and run wiring over to the sub panel too). Outside the house at the meter / main breaker box is a "toxic" environment due to it being the weather side of house, & 3 blocks from the Pacific Ocean, with high corrosion IN the main breaker box. I understand the need for a shut off for utilities, but the main 200 A breaker is fully accessible from outside, to all who might want to shut down the solar, and home system.


I am looking to minimize through exterior wall holes, and maximize protection from the elements. I have requested all the above from the designer, but would love to hear what may be legal in the electrician trade for "taping in".

Any thoughts??

Thank You!

Beachnut
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #2
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    Re: Connecting Solar into Home wiring, where at, and how??

    Generally how it is done is to put a breaker in the load center and backfeed the solar production there. There are designs to do a line side tap, but I think they are separately protected and added between the meter and the load center. THere are restrictions on how large the back feed breaker in a load center can be.

    Here is a pdf describing a line side tap.
    http://www.nmsu.edu/~tdi/pdf-resources/CC112.pdf
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #3
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    Re: Connecting Solar into Home wiring, where at, and how??
    Beachnut wrote: »
    Hello All!:cool:

    First time here, and posting!

    I just received my initial design diagram from my solar installer. They are proposing to:

    "TAP SYSTEM VIA INSULATION PIERCING ON LOAD SIDE OF MAIN BREAKER IN MAIN PANEL ENCLOSURE. CONDUCTORS ARE FIELD INSTALLED."

    So they look to run the power from the inverter in at the outside utility meter / main 200 A breaker box, taping in just below the 200 A breaker on the load side. (Per diagram schematic and above). They also look to install everything (inverter, meter, shut off switch and fuse), on the outside of the house wall, and run conduit, looping over my eve, down to it from the panels on the roof. Which I requested they not do in the bidding process. I have a rope installed from the attic space directly below the solar panel roof area, clear through to my basement sub panel for them to use to pull flex conduit in with. I am hoping this was just a miss communication from the site inspector, to the designer...

    Question for those in the know of electrical code: Do they have to tap in their below the 200 A breaker in my outside meter box? My sub panel is located less than 2' away from the outside meter / main breaker box, but located INSIDE my basement and protected. Can they "tap in" either on the load side of the incoming cable to the sub panel,, or, better yet, through a breaker IN the sub panel as there is space for many more breakers in my sub panel box.

    I desire to have all the equipment mounted in my basement, on a false wood panel interior wall, right next to the sub panel, that is like less than 2' below the outside main utility meter / breaker for the home. There is 6-8" of dead space between this interior false wood panel wall, and the sub panel mounted between exposed studs, and fully accessible through a door on this "false wood panel wall" that hides all of the sub panel, studs, and mess. (Easy to drill through, and run wiring over to the sub panel too). Outside the house at the meter / main breaker box is a "toxic" environment due to it being the weather side of house, & 3 blocks from the Pacific Ocean, with high corrosion IN the main breaker box. I understand the need for a shut off for utilities, but the main 200 A breaker is fully accessible from outside, to all who might want to shut down the solar, and home system.


    I am looking to minimize through exterior wall holes, and maximize protection from the elements. I have requested all the above from the designer, but would love to hear what may be legal in the electrician trade for "taping in".

    Any thoughts??

    Thank You!

    Beachnut
    A couple of things...

    I'm curious about the bit about piercing the insulation on the load side of the main breaker. Isn't the main breaker mounted on the busbars of the main panel? The main breaker must be separate from the main panel and connected by insulated conductors; if so then this would be a load side tap.

    As to where the interconnect is, electrically - if you place your interconnection in a subpanel, the maximum breaker size you can backfeed from an inverter is 20% of the rating of the busbars in the sub, assuming that the main breaker in the sub is rated the same as the busbar. This 120% rule also applies to the main panel. It sounds like the size system you are having installed may be too large for a backfed breaker in either the subpanel or the main panel, hence the load side tap your installer is proposing.

    And about wanting to run DC through your house to the inverter - I am pretty sure that this would necessitate a DC disconnecting means on the roof and running the DC conductors in conduit where they are inside the house envelope. Flex conduit may not be allowed. Additionally, whenever there are roof penetrations, the installer incurs a liability for the integrity of the roof membrane and preservation of whatever warranty is in force for that roof. Many installers do not want to expose themselves to that vulnerability.

    Good luck with your system.
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  • Beachnut
    Beachnut Registered Users Posts: 3
    #4
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    Re: Connecting Solar into Home wiring, where at, and how??

    Thank You all for your replies.

    I spoke with the designer today and he agreed to all of my suggestions. (Run the electrical through the roof - attic - wall - to the sub panel in basement, to install the inverter, and sunrun meter, & any other equipment inside the basement on the wall by the sub panel.) Also agreed to bring the solar power in through a 20 A breaker installed into my 225A sub panel, (which is fed by the main 200 A breaker outside, under the PG&E meter). Since the "system operating current is 8.42 A" and the "system short circuit is 11.19 A" I would think a 20 A breaker would be more than enough to feed through. (In fact, would it even trip with only a 11.19 A short?)

    I figured one more hole through the roof for the electrical should not be any worse than the other 10+ holes the racking will be punching through the roof! It sure beats a conduit run on the roof, and looping over the eve, and down the wall!!! I will for sure be watching for leaks for the next few years!

    So looks like it all worked out! Now just waiting for insulation near the end of the month..
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #5
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    Re: Connecting Solar into Home wiring, where at, and how??
    Beachnut wrote: »
    ... Since the "system operating current is 8.42 A" and the "system short circuit is 11.19 A" ...
    What do you mean by "system operating current" and "system short circuit"? Is it an off grid inverter? Grid tied inverters generally have a maximum output current rating and nothing else; there is no short circuit current rating because a GT inverter cannot feed a short. What inverter are you installing?
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