Martin,
Micro inverters are the safest. Opening a string under load is
dangerous. Having qualified personnel servicing the equipment is
essential.
My point is that an isolated incident is not statistical data. All
technologies have their hazards. The number of electricians injured by
various
Drake, I concur with your approach on this item -
1. Either the shock hazard was reduced by NEC 690.12 with MLPE for the
workers *too* or folks have been qualified persons in accordance with NEC
690.4(C) to recognize and avoid the shock hazard for string inverters.
2. Specifically, there's this
I live in a small town, so our outreach probably has greater impact. We
have gone to the FD meetings, we tell them about the system types and
definitions, quiz them and follow up. So, I think depending upon
training, which is not a one shot deal, it can have an impact. They seem
relieved.
On 202
FM100 has onboard AFCI
http://www.outbackpower.com/products/charge-controllers/flexmax-100-afci
I hope this helps.
Take Care All
From: RE-wrenches On Behalf Of
Jerry Shafer
Sent: Wednesday, April 29, 2020 11:34 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Rapid Shutdown Compliance
Wrenches
We
I agree: utilize the formal process, ideally with a group of folks. If you
are a SEIA member, get involved in their Codes and Standards process. The
additional directory language you suggest is not likely to be valuable to
many first responders without significant training and documentation, and
To change this, we need to recognize we are "fighting City Hall", and I
doubt the CMP will be motivated to make changes on their own. Maybe
this has always been more political than technical, but it seems that
those who are opposed to the current requirements need to make it known
through the
If first responders are the point of all the rapid shutdown, there needs to
be better exemptions. I personally have a 20kW solar array on a 100 year
old unused barn at my farm. The roof is at 50 degrees slope and needs a
60ft boom lift to access. There was significant extra expense and effort
for t
I believe Rapid Shutdown was mostly a solution looking for a problem.
The only way I see this becoming "reasonable" is to present "grievances"
to the Code Making Panel WITH a solution for their consideration. Based
on experience from being part of an outreach program that taught
approximatel
Spending more time on the roof, while putting more equipment and parts
to meet MLPE, means more trips up the ladder, which increases, not
decreases the #1 worker safety danger: Falls. Please correct me if I
have somehow misunderstood this, but MLPE is not making installers safer
based on OSHA i
Interestingly enough, the data on the link [9] provided shows accidents
from gas explosions, falls, health problems and industrial injuries.
None of these incidents could have been prevented by module level power
electronics. This is typical of the data that I've seen so far.
---
On 2020-05-0
There could be an issue of encouraging MLPE for worker safety?
1. This is data involving incidents with workers in the OSHA Fatalities
and Catastrophe Investigation Summaries found here:
https://www.osha.gov/pls/imis/AccidentSearch.search?p_logger=1&acc_description=&acc_Abstract=solar&acc_keyword
off by the RS system that needs AC to activate it firstDon BarchEnergy Solar
Date: Tue, 5 May 2020 08:35:51 -0400
From: Tump <t...@swnl.net>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] Rapid Shutdown Compliance
Message-ID: <7273560e-f55b-4007-8
We are running into the same problem with battery back-up, grid-tie
systems. Many Rapid Shutdown solutions turn off the array when utility
power is off, which isn't desirable. We have one client with an underground
service and the local AHJ wants the RS initiating device near the meter (as
our Cana
How about a SPDT switch, all one is doing is supplying AC voltage from the
utility, (powering the MLPE box's Ac to Dc converter) their utility or SSP
from the SB’s utility.
> On May 4, 2020, at 8:04 PM,
> wrote:
>
> Many customers ask about keeping power alive when the grid is down. Besides
Many customers ask about keeping power alive when the grid is down. Besides battery backup, I advocate the Secure Power feature of SunnyBoy inverters. But the problem with MLPE is that it is incompatible with Secure Power. When the grid goes down the MLPE disconnect each solar module's DC feed. So
1. I use a MLPE residential ground-mounted solution - rapid shutdown or
not. w/Accessible MLPE.
2. There is a maximum physical string length for me to keep in mind, for
instance, found here:
"In the context of this document, string length refers to the number of
optimizers and modules in the str
I was told at a training a couple years ago that there were going to be
some modules coming out soon that had a microchip in the module junction
box which would replace the diodes and effectively work as MLPE. I have not
heard anything about that recently though. Does anyone know what I am
talking
Since I only work with off-grid systems, I find the 690.12 exception
starting in NEC 2017 for ground-mounted systems with DC equipment in a
separate structure intended only for PV components, is very useful for
avoiding expensive, unneeded RSS equipment. Many folks don't like the idea
of a battery
I would like to see real data on the fire risk of string inverters.
Anecdotal problems are not data.
The industry is definitely heading toward MLPE due to the rapid shutdown
requirements. In many cases MLPE makes sense, in other cases it doesn't.
Systems that are more cost effective and relia
I agree w/ Ray as most of my work is Off grid. Incorporating addition failure
points ( RSD modules. optimizers ect.) for a system that is usually quite a
distance from service, be it my service or the fire departments, I find the
justification very hard. Ive replaced your micro inverters at 0* d
All - Ray has a good point, the discussion here is really about two
different types of systems - mainstream ongrid PV, and small scale (and a
relatively small market) offgrid PV. It's really tough to design a small
offgrid system (especially DC coupled) with rapid shutdown. I think it's
just a case
Deadline for 2023 NEC® public input is in September.
Brian
> On Apr 30, 2020, at 7:12 AM, Ray wrote:
>
>
> Hi Jerry;
>
> This isn't about us not being willing to learn the tech. All of us are
> constantly learning about new code changes, new inverters, and solar modules
> that change spe
Hi Jerry;
This isn't about us not being willing to learn the tech. All of us are
constantly learning about new code changes, new inverters, and solar
modules that change specs every few months. We are voluntarily adopting
new technology (like Lithium Ion batteries) when that technology is co
Wrenches
We are taking two very different issues and mixing them together. RSD and
Arc-fault are different, arc fault will and does prevent fires, RSD was
brought out of the need to vent a roof that even with the meter pulled have
500 volts and resulted shocks to fire fighters by cutting into roofs
Rapid Shutdown does not prevent fires; it was originally drafted to
allow firefighters to vent a roof without being hindered by energized PV
arrays. This rule was expanded to include other DC wiring from PV
sources.
As for PV safety, I'd like to see some significant, statistical evidence
that s
"Rapid Shutdown does not prevent fires."
Not true. If the effect of RS is to steer the market to MLPE, I believe it
has a significant impact on reducing fire risk. As one who has watched a DC
conductor fire smolder out of control, I am sold on an AC module or
microinverter architecture. While RS o
I have been to several PV fires for string inverter systems, both
commercial and residential, and have seen many DC systems at serious risk
of fires or in various stages of melted insulation and connectors. Most of
these systems have exhibited good to excellent workmanship. Things just
went wrong.
my two cents worth, 690.11 says turn off from all arcs, that means serial
and parallel
that means module lwevel shutdown
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I agree, 690.12 should have exemptions for lower voltage, lower power
systems, and shorter runs; especially off grid. 10 years ago, I was
promoting some type of remote controlled disconnect at the array, but
that was for voltages over 400v, with unprotected conduit runs over a
100 ft long, on
My 2 cents are related to the very few times I have had to do RS for
offgrid. My advice is to install whatever the inspector wants, assuming he
can't be convinced of the mindless requirement. Complete the installation.
Do the right thing after by abandoning it. Have the client remove the RS
signi
Hi Drake
I will disagree, there have been many roof top fires.
But regardless we have to do these new regulations and I for one welcome the
safety.
The main issue is accessing the faulty/suspect component under the module
possibly requiring removing multiple modules, a slow and expensive pr
Clearly, rapid shutdown increases cost and reduces reliability. Given
the excellent safety record of PV, prior to rapid shutdown being
required, it is unnecessary. The few anecdotal incidents of PV fires
were not enough to justify the requirement, especially on smaller
systems.
According to a f
Hi Corey - As we've grown, and as our fleet of installed systems has grown,
I've become increasingly interested in choosing an inverter solution that
shows per-module production data. I realize that you specifically asked not
to consider optimizers or microinverters, but I wonder if that will be a
So far rapid shutdown has been a nightmare. It’s added a lot of cost for no
measurable benefit.
Using always off devices like midnight solar and Tigo makes it impossible to
test open circuit voltages. Which opens the door to tons of problems when
commissioning systems.
Also we’ve been trying ou
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