RSB survival and placement

[negatron]

My system has been approved by the electrical inspection agency.
The side of the array where power feeds the equipment ends up being about 11 feet off
the eave edge. Not exactly sure why the engineer shifted it so far off but I might go
over the issue with him shortly. As it stands now the RSBs would be placed
on the roof meeting the NEC 10 foot guideline. My first main concern is that on a
hot day the roof temperature at the shingles hits 140F and the SMA RSBs have
a recommended max op temp of 147F, not much wiggle room at the max.
So Question 1 would be
Are those RSBs going to survive that heat for even a few
years or burn out on a hot day in August?

Even if the array design was shifted so that it was maybe 4 feet off the eave edge,
getting the boxes within the 10foot NEC spec and on to the side of the house
in a more sheltered spot would end up with the RSBs being mounted
at about 8 feet above ground level. I dont mind that since theyre passive
and would be in a better spot but the electrician is probably going to
grumble about it before or during installation.
So Question 2 would be
How rigid is the NEC code 10 foot rule and is there any practical language in there for
mounting those RSBs a more practical distance from the array?

Not really interested in having the engineer add extra cost to my project by doing a
rework of that array layout page but not an impossible task and would probably
have to have the mod approved; a minor inconvenience.
Any advice on these issues?

Thanks
Negatron

[sensij]

Hopefully you can cut and paste again, but after pasting, delete and re-type the quotation marks, dashes, and apostrophes that cause the text editor to truncate your message.

[negatron]

Hopefully you can cut and paste again, but after pasting, delete and re-type the quotation marks, dashes, and apostrophes that cause the text editor to truncate your message.

I will; sorry bout that issue

[max2k]

.... I dont mind that since theyre passive...

I have only one comment- they're far from being passive, there's fair bit of circuitry inside. I can post pic later of RSB-2S-US-10 internals if you like.

[negatron]

I have only one comment- they're far from being passive, there's fair bit of circuitry inside. I can post pic later of RSB-2S-US-10 internals if you like.

No need for the pics thanks.
I saw the guts and took pics too.

actually a very nice inside that box.

Maybe passive was the wrong word.

Just want to hear that they can handle the great outdoors up there.


Thanks

[sensij]

This thread says that maybe your concerns are justified:

https://www.solarpaneltalk.com/forum...shutdown-a-pos

I don't think you'll find any wiggle room on the 10 ft limit, if your inspector actually gets on the roof to verify it was located where it should be,

[negatron]

This thread says that maybe your concerns are justified:

https://www.solarpaneltalk.com/forum...shutdown-a-pos

I don't think you'll find any wiggle room on the 10 ft limit, if your inspector actually gets on the roof to verify it was located where it should be,

Thanks. I read that thread a few weeks ago.
I just thought it was a harsh environment for the electronics for those RSBs being up there on the roof.
There up there on the roof getting some serious heat.
Then they can get clobbered with rain from a thunderstorm.
And in the winter can get buried under ice and snow just waiting to suck in moisture
even though they are sealed up with that cover seal and water tight connectors.
If I have to I'll get up there and put some kind of awning over them that will give them some protection later on.
Everything about this project is by the book not Rube Goldberg in any way.

I'll go over the matter of placement before we set up the install date.

My compliments to the site and membership for all the help that gets passed out to people.
Some really experienced people who respectfully answer some strange questions from people in strange places doing strange things.

negatron

[max2k]

Thanks. I read that thread a few weeks ago.
I just thought it was a harsh environment for the electronics for those RSBs being up there on the roof.
There up there on the roof getting some serious heat.
Then they can get clobbered with rain from a thunderstorm.
And in the winter can get buried under ice and snow just waiting to suck in moisture
even though they are sealed up with that cover seal and water tight connectors.
If I have to I'll get up there and put some kind of awning over them that will give them some protection later on.
Everything about this project is by the book not Rube Goldberg in any way.

I'll go over the matter of placement before we set up the install date.

My compliments to the site and membership for all the help that gets passed out to people.
Some really experienced people who respectfully answer some strange questions from people in strange places doing strange things.

negatron

for what's it worth I'm placing my RSBs under the panels to slightly mitigate those issues. The thread with RSBs shutting down never got a closure so I consider it 'unproven' until my own start to shut down . In that thread it didn't really look like temperature related as OP stated 'once every few months' - if RSBs were shutting down due to temperature OP would face much more downtime. I still went with string + RSS + inverter design as in my mind RSB is a box with relay and its own power converter, supposedly the simplest roof circuit from all possible.

[negatron]

In that thread it didn't really look like temperature related as OP stated 'once every few months' - if RSBs were shutting down due to temperature OP would face much more downtime. I still went with string + RSS + inverter design as in my mind RSB is a box with relay and its own power converter, supposedly the simplest roof circuit from all possible.

yeah, if the RSBs are shutting down prematurely its easy enough to check at the inputs to the DC disconnects attached to the inverters.

same here on the system strings into RSbs into inverters as the system gets full sun all day.
guess well see how good the SMA 5000 TL units are too.
I kind of wished SMA had been a bit more considerate with the RSBs as there 4 into 2 and the dc
disconnects are 2 into 1
and due to the array output the engineer had to make the system with 2 RSB units.
but only a minor ouch based on the total cost. no bid geal.

[negatron]

I have only one comment- they're far from being passive, there's fair bit of circuitry inside. I can post pic later of RSB-2S-US-10 internals if you like.

Since you've opened one of these boxes, how about the any of the TL series inverters? I'll get to pop open one before installation and attachment of the DC disconnect boxes. The owners manual say that the varistors inside should be replaced every 10 years but they are sure going to outlive me. Is there any possibility that say the difference between a 5000TL and a 6000TL is just those varistors and one can simply upgrade the inverter unit wattage if a few higher wattage panels are put in?

[max2k]

Since you've opened one of these boxes, how about the any of the TL series inverters? I'll get to pop open one before installation and attachment of the DC disconnect boxes. The owners manual say that the varistors inside should be replaced every 10 years but they are sure going to outlive me. Is there any possibility that say the difference between a 5000TL and a 6000TL is just those varistors and one can simply upgrade the inverter unit wattage if a few higher wattage panels are put in?

I never opened any inverter and I bought SMA SunnyBoy 3.8 kW for my system. In general varistors have a lifespan and eventually they would fail shorting AC line to inverter and probably burning some internal fuse in the process. This is an easy fix if you know your way around electronics. I don't think it's specific to SMA designs either they just might be the only ones who mentioned varistor aging.