Rapid shutdown on ground mounted array

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mickri
mickri Registered Users Posts: 17 ✭✭
in Grid Tie and Grid Interactive Systems #1
I am in the final stages of planning a ground mounted system.  I am located in Fresno County California.  The only thing left to decide on is the inverter and do I need a rapid shutdown.  The system is 3.8 kw.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Your local city/county building code will state if you need rapid shutdown.   Generally, that's only required for an occupied dwelling, but who knows what is actually written into their code.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #3
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    You probably do not need one for a ground mount. However, it may be easier if you get someone who is adamant to just do what they want and then "fix" it later. I have seen this go both ways in your area.   Below is a link to what I use from Schneider. You can drop me an email also. Are you out in the foothills?

    https://solar.schneider-electric.com/product/mppt-disconnect-rs-for-nec-2017-compliance/
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #4
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    I am out in the foothills in Squaw Valley.  13 miles east of Orange Cove.  I'll either call or email the County.  I found them easy to deal with when I replaced the roof on my house.  Sometimes it helps to know the answer to your questions before you ask when dealing with government officials.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #5
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    NEC code, RSS is only required when panels are mounted on a structure that is a living space. That said, your local code enforcement can dream up anything they want and try and make you comply. Been there and have the tee-shirt.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #6
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    I bet you do not have the wildfire tee shirt. That is the latest that is being used out west to make people comply with stupid regulations that are not understood by the AHJ. Many NABCEP installers are trying to get this idiotic implementation of RSD fixed or abandoned for residential. It has caused fires and for the most part it is installed in plastic boxes on a roof. 

    The reliability issue for offgrid is only made worse by having electronics outside in the weather, and then sold/installed in plastic JB's...

    I do not recommend saving the good wine!  Enjoy it while you can!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
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    Dave Angelini said:
    I bet you do not have the wildfire tee shirt. ......
    I want to see the tee shirt !
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #8
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    Give me some time Mike, I just got back from Nevada and need to get organized. Caldor is 2 miles from Stateline where I just finished a system for some Nevadans. Once caldor fire is out of the sierra it is just the flatlands of the Carson Valley. Going to be a nevadan myself one day if our local hospital does not get rebuilt.

    You fired up that xwp right? Time is ticking on warranty! I just told somebody bad news on that.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #9
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    >  You fired up that xwp right? Time is ticking on warranty! I just told somebody bad news on that.

    Gagh !  it's been the summer of delays.  Heat, someone else's gear burned up, I was in hospital (cancer)
    but now I'll get on Alex's case to get this done soon.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,144 ✭✭✭✭
    #10
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    Mike, You doing alright now?
    Marc
    I always have more questions than answers. That's the nature of life.
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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #11
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    Sent an email off to Fresno County Building.  Never got a response.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #12
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    Probably need to call.   Below is a great example of RSD from a buddy.


    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #13
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    I called and left a message.  Never got a call back.  Next time I am in Fresno I will go in to talk to them.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #14
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    Good Luck with going in. In our county the doors are locked and they may come out and see you if they are not swamped with understaffing.  If I were you, and this is offgrid, I would just do the mount with the idea that you can do what they want later. It is easy to do later also, and easy to undue after they are gone.

     Much easier to ask for forgiveness than permission. Also it is best not to tell them anymore than they require.
    They are suppose to help you!  Often, that is not the case!    500+ clients of experience writing here!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #15
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    Never got into Fresno County.  In the interim I moved to a fixerupper house 15 miles outside of Paso Robles, CA.  San Luis Obispo County. I brought all of my solar stuff with me.  Most of the fixing is done and the next project is to install my solar system.  The only thing left to buy is the inverter.  The array will have 3.84 KWH  One string with 1800 and the other string with 2040.  Total 3840.  Would a 3.8 kwh inverter work with this slight overage or do I need to go to a larger inverter? 
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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #16
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    The new place previously had a solar system.  It was close to 20 years old and may not have been working properly.  The seller's estate removed the panels and the inverter prior to putting the home on the market.  The A/C disconnect is still here and there is a 30 amp breaker on the service panel.  All PG&E wants is a new interconnect application from me once I have installed the new panels and inverter.  Waiting for a call back from the County.  They have been good about calling me back with other questions that I have had.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #17
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    What is the battery bank? Voltage, AH, type of battery bank (FLA, AGM, Lithium Ion, etc.)?

    What is your planned daily usage (Watt*Hours per day)?

    What Brand/Model/Battery Bus voltage of AC inverter? Is this a combo inverter-MPPT charge controller-etc.?

    Generally like to define the loads (peak watts, WH per day, amount of sun, etc.) to define the VDC/AH/type of battery bank...

    A good starting point is a maximum of 1,000 Watt AC inverter per 100 AH @ 48 VDC battery bank (or 200 AH @ 24 VDC battery bank and such)... 1/2 that size AC inverter is a good match (don't oversize the AC inverter--It wastes power and is extra costs you may not need).

    Generally want 10-13% minimum rate of charge for battery bank from solar array for full time off grid. But also need to match the "max inverter per 100 AH of battery bank, and hours of sun by season for per day).

    Generally, there is not a "fixed" requirement for sizing the AC inverter (power usage) vs the size of the solar array--Which needs to be sized to the MPPT charge controller specs... Think of the battery bank as the "heart" of your system... Array + charger keeps the battery bank "happy". And the battery bank supplies power to the AC inverter (properly sized bank/inverter/wiring).

    In real life, the array + charge controller also supplies power to the AC inverter during daylight hours (as we as charging the battery bank)--But worst case is night anyway (no solar, just battery bank supplying loads).

    Sometimes you have to take daytime loads into account (i.e., running a fabrication shop during the day)--Shut down at night. But if you need to run during bad weather (no sun)--Then you still need to meet the "night time" power and energy requirements too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #18
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    My system is a simple straight grid tie system.  No battery bank back up. The electricity runs from the array to the inverter to the AC disconnect to the service panel.  Just typical house hold uses for the most part.  I live by myself.  So other than lights and the electric HVAC I don't run two things at the same.  Don't even run the HVAC if I am not in the house. 

    My total electrical usage last year was 2123 kwh if I added the numbers up correctly that I got from PG&E.  My usage will go up once the solar system is installed because I will run the HVAC more than I do now.

    I am thinking about using a SMA SB3.8-1 SP-US-41 inverter. 
     
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  • mickri
    mickri Registered Users Posts: 17 ✭✭
    #19
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    Have talked to both the County and PG&E.  PG&E tells me once the system is installed and has final inspection from the county to fill out the paperwork to connect to the grid and don't throw the switch until I get the approval from PG&E.  The County tells me that they have lots of homeowners doing their own installs.  Bring in all of my plans and if everything is ok they will issue me a permit over the counter.  Should have plans done by next week. 
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