NEC 2017 and RSS - I feel so blessed

rollandelliott

these cost about the same as the sma product:
http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=26&productCatName=Combiners, Disconnecting

billybob9

All other Rapid shutdowns are Optimizers (one per panel ) so too expensive. If you don't have a shading issue SMA is the way to go at $250. You're right about shading with a reflective metal sheet at the end of the array. I would bend it slightly so the top would be curved. If this met code SMA might start recommending it.

rollandelliott

So what ever happened to the original poster? did he pass inspection? Anyways to answer his question, the 2017 NEC does module level shutdown DOES NOT apply for external structures like pergolas, ground mount arrays, etc. The midnite solar youtube video he linked to states that at 50:00 mark as well as this web article 
https://www.purepower.com/blog/2017-nec-690.12-rapid-shutdown-important-changes

rollandelliott

this is midnite solars solution http://www.midnitesolar.com/productPhoto.php?product_ID=672&productCatName=RAPID-SHUTDOWN-SYSTEM-NEC-690.12&productCat_ID=44&sortOrder=1&act=p
one is needed PER solar panel, & you need a transmitter or bleed down box which adds another $100 to $250 which means a 10K system is going to cost about $2300 more, or $0.23/watt. if the local permit department requires a combination disconnect box those are $700 to $800 and if they require a birdhouse those are $250 more.

why spend $3000 on all of the above if one can just build a pergola instead? Now granted Pergolas that big will cost $3000 in materials, and if you pay someone to build it, you are looking at $10,000 or more. And engineered drawings will cost $1000. so not really cheaper unless you DIY. 


Seems like ground mount systems are going to become more appealing given the cost for this NEC 2017 requirement. 

rollandelliott

All other Rapid shutdowns are Optimizers (one per panel ) so too expensive.
Pretty sure that is now the requirement!  the sma RSS module appears to be 2014 compliant, but not 2017. 

This new code is a huge boost to using micro inverters instead of central string inverters. Basically the tables have been flipped micro inverters will now be cheaper then string tie inverters, which have historically always been less expensive. 

rollandelliott

where can I get a copy of nec 2017 without paying $100 for the whole book?

boB

rollandelliott, I totally agree that if you can put the array on a pole it is better overall...  Also cools the PV down better I think.

The bleeder box is not necessary unless the inverter itself does not do that automatically.  We had to build that box for the inverter or two we had tested with that lacked the 30 second bleed down.  I think most of them bleed themselves down now.  They also have to bleed down from PV+ to gnd as well as PV- to gnd and some did not do that either.  The non-isolated ones basically had that problem.

This whole module level bleed down thing I think was overblown.  Just when solar was getting cheaper, they have to step in and screw that all up.

BB.

I am not sure now, but in times past, sometimes you could find the NEC manual in a city/county code archive. Their law required access to the code without having to purchase the book.

-Bill

mcgivor

BB. said:

I am not sure now, but in times past, sometimes you could find the NEC manual in a city/county code archive. Their law required access to the code without having to purchase the book.

-Bill

Or perhaps your local library, once a great source of books, before the digital age which prevents us from venturing out into the twilight zone of reality. 

aksala

Getting back to my original post - I simply left the solar and other off-grid components out of the build until after inspection. The only thing there was to inspect was the normal main panel and a manual transfer switch for generator input to run the house. I opted to install the rest myself and skip the new requirements. Putting panels on a pole, or what would have been two poles or taking up a bunch of additional space on the ground and trenching and wire etc., just wasn't going to happen when I had a perfectly good roof to install onto and that gave me a bit more height for that late fall/early spring low elevation sunlight. 

aluminumwelder

MY AHJ said I have to have RSS rapid shutdown because 35' of high voltage Dc wire in metal conduit and 2 inverters are mounted to the side of my house to main panel. I should of just made a board on my picnic shelter and mounted it all to that, would of saved so much headache! I guess you should never assume Rapid does not apply to ground mounts. All depends on your AHJ. 

Dave Angelini

Never assume ! Words of wisdom!  Death and Taxes are givens.

You can always try and discuss it with the AHJ. They often are reasonable for Offgrid. Sometimes, you just have to do it and fix it later