Tesla fires, Amphenol connector

https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

 

[John Larkin]

On Tue, 27 Aug 2019 09:53:15 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Tuesday, August 27, 2019 at 12:09:34 PM UTC-4, jla...@highlandsniptechnology.com wrote:
https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

Most likely the Tesla installers abused the component called a "connector"-LOL. The panels themselves didn't catch, looks like they ignited the roofing tar. Supposedly that stuff is fire resistant up to a point, then it melts and is highly flammable and a really good way to spread the fire all over the place.

It looks like the connector is heavily dependant on the copper wires
to keep it cool. One good way to start a fire is to believe the 65 amp
rating but use smaller, or long thermally insulated wire.

Still, the little probably-stamped, tin-plated contacts look kinda
tacky.

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

The 65A rating is for #8 wires, sheesh! It's only
rated at 15 and 20A for #14 and #12 wire. A string
of 300W panels can't create more than about 9 amps.


--
Thanks,
- Win

 

On Tuesday, August 27, 2019 at 12:09:34 PM UTC-4, jla...@highlandsniptechnology.com wrote:

https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

Most likely the Tesla installers abused the component called a "connector"-LOL. The panels themselves didn't catch, looks like they ignited the roofing tar. Supposedly that stuff is fire resistant up to a point, then it melts and is highly flammable and a really good way to spread the fire all over the place.

 

[John Larkin]

On 27 Aug 2019 10:17:16 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

The 65A rating is for #8 wires, sheesh! It's only
rated at 15 and 20A for #14 and #12 wire. A string
of 300W panels can't create more than about 9 amps.

Seems like big arrays can be series-parallel wired. I guess that saves
on inverters, one big inverter instead of several small one.

Copper is expensive!

Probably Tesla wants to blame Amphenol.

 

[Winfield Hill]

John Larkin wrote...

Seems like big arrays can be series-parallel wired.
I guess that saves on inverters, one big inverter
instead of several small one.

The inverters I've looked at had multiple inputs
to handle many strings. Tying strings in parallel
doesn't work, they must be individually optimized.
But once they start combining string outputs, they
supposedly go through a junction box, and shift to
metal conduit and a totally different kind of
wiring. That's what happens on my roof.

> Copper is expensive!

Actually, not. Recently I was shocked at Alpha
and Belden's high prices, and did some research:
raw copper is a tiny fraction of their price.


--
Thanks,
- Win

 

On Tuesday, August 27, 2019 at 1:10:31 PM UTC-4, John Larkin wrote:

On Tue, 27 Aug 2019 09:53:15 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Tuesday, August 27, 2019 at 12:09:34 PM UTC-4, jla...@highlandsniptechnology.com wrote:
https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

Most likely the Tesla installers abused the component called a "connector"-LOL. The panels themselves didn't catch, looks like they ignited the roofing tar. Supposedly that stuff is fire resistant up to a point, then it melts and is highly flammable and a really good way to spread the fire all over the place.

It looks like the connector is heavily dependant on the copper wires
to keep it cool. One good way to start a fire is to believe the 65 amp
rating but use smaller, or long thermally insulated wire.

Still, the little probably-stamped, tin-plated contacts look kinda
tacky.

You can see from the datasheet that the derating nosedives at 70oC. I'm pretty sure the ambient was running hotter than that on the flat roofs in full sun.
http://www.amphenol-industrial.com/images/datasheets/IDS-17%20Helios%20H4.pdf
It most likely was not a one time failure. It was repeated cycling of overtemperature that caused the connectors to eventually crack. Doesn't that dumb panel protect itself against overtemperature? It is possible the mechanism of connector failure, some kind of intermittent short, defeated the panel protection.

 

[boB]

On 27 Aug 2019 11:09:13 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

Seems like big arrays can be series-parallel wired.
I guess that saves on inverters, one big inverter
instead of several small one.

The inverters I've looked at had multiple inputs
to handle many strings. Tying strings in parallel
doesn't work, they must be individually optimized.
But once they start combining string outputs, they
supposedly go through a junction box, and shift to
metal conduit and a totally different kind of
wiring. That's what happens on my roof.

Copper is expensive!

Actually, not. Recently I was shocked at Alpha
and Belden's high prices, and did some research:
raw copper is a tiny fraction of their price.

Somewhere I had read that the arrays were "de-energized"....
Doesn't make much sense that a connector's series resistance will
cause any heat if the series circuit is opened.

There is more going on here that they are not talking about.
Could even be bad bypass diodes in the modules. Don't know where
their modules come from but maybe China ?

And combiner boxes with series fuses or breakers are used when three
or more strings are combined.
Series fuse ratings are usually 15 amps but some more than that. Maybe
20A which is why combiners are required so that a bad (shorted) module
cannot be "ganged up" on by the other strings.

Also, DC arc fault protection and ground fault detection/protection
are required these days as well as RSS Rapid Shutdown Systems.

 

[Jeff Liebermann]

On Tue, 27 Aug 2019 11:56:33 -0700, boB <boB@K7IQ.com> wrote:

Somewhere I had read that the arrays were "de-energized"....
Doesn't make much sense that a connector's series resistance will
cause any heat if the series circuit is opened.

<https://www.nytimes.com/2019/08/20/business/walmart-tesla-lawsuit-fires.html>
But last November, the roof of a Walmart in Yuba City, Calif.,
ignited. When the blaze was discovered, wires on the roof
were still sparking, the complaint said, even though the
solar panels had been disconnected for five months.

Either:
1. The wire insulation had been penetrated by the metal frame or
conduit
2. Some source of heat melted the wires
3. Someone goofed and used CCA (copper clad aluminum) wire.
4. Something was able to produce more than the rated 9A short circuit
current for a 300A panel.

If "de-energized" means tripping the RSD (rapid shut down) switch,
then yes, there is no load on the panel, and therefore no current to
cause heating. However, if it was de-engergized by shutting down the
micro-inverters or a central grid-tie inverter, these inverters, or
the associated wiring, might still present a load.
<http://www.cleanenergybrands.com/shoppingcart/knowledgemanager/images/midnite%20rapid%20shutdown%20birdhouse%20box.jpg>

I had originally thought that because of the lack of similar solar
panel fires at locations other than Walmart, that it must be either
something unique in the components used by Tesla, or something in the
manner they were installed. However, that just changed as Amazon is
now indicating that they had a similar problem:
<https://www.forbes.com/sites/rachelsandler/2019/08/26/amazon-also-experienced-tesla-solar-panel-roof-fire/#47aca76172c2>
The article claims that Tesla knew about the problem and is blaming
the Amphenol connectors.
<https://www.businessinsider.com/tesla-project-titan-replace-bad-solar-panel-parts-2019-8>
Specifically, Tesla was replacing connectors and optimizers,
parts that are meant to regulate the amount of energy flowing
to a solar panel. Too much energy can cause a fire.

The connector in question is on the SolarEdge optimizers:
<https://www.solaredge.com/us/products/power-optimizer>
"Optimizer" seems to be the same as "micro-inverter". The modules are
mounted on the back of the panels and are far away from the roof. In
my never humble opinion, a burning module is not likely to start a
fire at that distance.

The cables, with connectors at midpoint, are a different story. If
installed in the manner of the SolarEdge photo,
<https://www.solaredge.com/sites/default/files/2019-04/Installer-1000x654.jpg>
they might be dragging on the roof and start a fire. However, that
installation not to code according to current standards (NEC Article
690). The DC wiring is suppose to be enclosed in metallic (RMC, GRC,
IMC, or EMT) conduit or in a raceway or cable tray. The following is
form before the 2017 changes to Article 690, but does cover most of
the applicable and proposed wiring requirements:
<https://iaeimagazine.org/magazine/2015/04/14/support-of-exposed-cable-for-pv-systems-requirements-and-recommendations/>
If a connector caught fire, the fire would be contained to the
conduit, raceway, or cable tray. The enclosed DC wiring (part of RSD)
became effective on Jan 1, 2019, so it is likely that the Walmart and
Amazon systems were installed to an earlier NEC standard and therefore
might lack enclosed DC wiring. I can't tell from the burned out roof
photos if the DC wiring was protected by conduit, was dangling wire
dragging on the roof.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[boB]

On Tue, 27 Aug 2019 13:37:52 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Tue, 27 Aug 2019 11:56:33 -0700, boB <boB@K7IQ.com> wrote:
Somewhere I had read that the arrays were "de-energized"....
Doesn't make much sense that a connector's series resistance will
cause any heat if the series circuit is opened.

https://www.nytimes.com/2019/08/20/business/walmart-tesla-lawsuit-fires.html
But last November, the roof of a Walmart in Yuba City, Calif.,
ignited. When the blaze was discovered, wires on the roof
were still sparking, the complaint said, even though the
solar panels had been disconnected for five months.

Either:
1. The wire insulation had been penetrated by the metal frame or
conduit
2. Some source of heat melted the wires
3. Someone goofed and used CCA (copper clad aluminum) wire.
4. Something was able to produce more than the rated 9A short circuit
current for a 300A panel.

If "de-energized" means tripping the RSD (rapid shut down) switch,
then yes, there is no load on the panel, and therefore no current to
cause heating. However, if it was de-engergized by shutting down the
micro-inverters or a central grid-tie inverter, these inverters, or
the associated wiring, might still present a load.
http://www.cleanenergybrands.com/shoppingcart/knowledgemanager/images/midnite%20rapid%20shutdown%20birdhouse%20box.jpg

I had originally thought that because of the lack of similar solar
panel fires at locations other than Walmart, that it must be either
something unique in the components used by Tesla, or something in the
manner they were installed. However, that just changed as Amazon is
now indicating that they had a similar problem:
https://www.forbes.com/sites/rachelsandler/2019/08/26/amazon-also-experienced-tesla-solar-panel-roof-fire/#47aca76172c2
The article claims that Tesla knew about the problem and is blaming
the Amphenol connectors.
https://www.businessinsider.com/tesla-project-titan-replace-bad-solar-panel-parts-2019-8
Specifically, Tesla was replacing connectors and optimizers,
parts that are meant to regulate the amount of energy flowing
to a solar panel. Too much energy can cause a fire.

The connector in question is on the SolarEdge optimizers:
https://www.solaredge.com/us/products/power-optimizer
"Optimizer" seems to be the same as "micro-inverter". The modules are
mounted on the back of the panels and are far away from the roof. In
my never humble opinion, a burning module is not likely to start a
fire at that distance.

The cables, with connectors at midpoint, are a different story. If
installed in the manner of the SolarEdge photo,
https://www.solaredge.com/sites/default/files/2019-04/Installer-1000x654.jpg
they might be dragging on the roof and start a fire. However, that
installation not to code according to current standards (NEC Article
690). The DC wiring is suppose to be enclosed in metallic (RMC, GRC,
IMC, or EMT) conduit or in a raceway or cable tray. The following is
form before the 2017 changes to Article 690, but does cover most of
the applicable and proposed wiring requirements:
https://iaeimagazine.org/magazine/2015/04/14/support-of-exposed-cable-for-pv-systems-requirements-and-recommendations/
If a connector caught fire, the fire would be contained to the
conduit, raceway, or cable tray. The enclosed DC wiring (part of RSD)
became effective on Jan 1, 2019, so it is likely that the Walmart and
Amazon systems were installed to an earlier NEC standard and therefore
might lack enclosed DC wiring. I can't tell from the burned out roof
photos if the DC wiring was protected by conduit, was dangling wire
dragging on the roof.

Did one of these articles say that Tesla was using Solar Edge for
these installs ? I know they were going to use them a while back...

 

[Tim Williams]

"Winfield Hill" <winfieldhill@yahoo.com> wrote in message
news:qk3rk901p6m@drn.newsguy.com...

Actually, not. Recently I was shocked at Alpha
and Belden's high prices, and did some research:
raw copper is a tiny fraction of their price.

Raw in what sense? There's a lot of processing between spot price and drawn
wire, and more still to make that into stranded insulated wire.

Also, were those brand names priced manufacturer-direct, or via distributor?

The overhead from Chinese production -- if that's what you're comparing
with -- is indeed very small, something like one third.

(It may be even more, if you don't notice or mind that you actually got
copper plated/clad steel or aluminum!)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[Jeff Liebermann]

On Tue, 27 Aug 2019 15:25:52 -0700, boB <boB@K7IQ.com> wrote:

Did one of these articles say that Tesla was using Solar Edge for
these installs ? I know they were going to use them a while back...

Sorta. Tesla does use SolarEdge, but allegedly may not have used them
on the Walmart rooftops that caught fire:
<https://www.businessinsider.com/tesla-project-titan-replace-bad-solar-panel-parts-2019-8>
The faulty parts in question were connectors - Amphenol
H4 connectors - and SolarEdge optimizers.
(...)
SolarEdge responded to Business Insider noting that it
was not in any way involved in the lawsuit between
Walmart and Tesla, nor are SolarEdge products on
the rooftops cited by Walmart in the lawsuit.
(...)
We can affirm that to our knowledge, our power
optimizers have never been the source of any fires.

At this time, I'm not sure whom to believe.

SolarEdge CEO & Founder Guy Sella Dies, Aged 54
<https://cleantechnica.com/2019/08/26/solaredge-ceo-founder-guy-sella-dies-aged-54/>

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Winfield Hill]

Jeff Liebermann wrote...

The connector in question is on the SolarEdge optimizers:
https://www.solaredge.com/us/products/power-optimizer
"Optimizer" seems to be the same as "micro-inverter".

Not that it's relevant to your point, but an "optimizer"
and a "micro-inverter" are two completely different beasts.
An "optimizer" individually takes each panel's output and
DC-DC converts it to an optimum series voltage so all its
available power is delivered to the series string, which
must have equal current through each panel's optimizer.

OTOH, there's a "micro-inverter" on each panel, taking its
output and converting it to Vac line voltage, delivering as
much AC current as it can for its instantaneous power level.

E.g., my Enphase micro-inverter roof puts out 60Hz 230Vac,
up to 12 amps per section, and 37A max total. But if the
230Vac line source is removed, all microinverters cease to
function, and the system is OFF. It's possible an optimizer
system will still try to maintain 600 to 800 V at its output.


--
Thanks,
- Win

 

[Jeff Liebermann]

On 27 Aug 2019 18:10:54 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Jeff Liebermann wrote...

The connector in question is on the SolarEdge optimizers:
https://www.solaredge.com/us/products/power-optimizer
"Optimizer" seems to be the same as "micro-inverter".

Not that it's relevant to your point, but an "optimizer"
and a "micro-inverter" are two completely different beasts.
An "optimizer" individually takes each panel's output and
DC-DC converts it to an optimum series voltage so all its
available power is delivered to the series string, which
must have equal current through each panel's optimizer.

OTOH, there's a "micro-inverter" on each panel, taking its
output and converting it to Vac line voltage, delivering as
much AC current as it can for its instantaneous power level.

Notice that I said "seems" which is my way of saying that I'm not
quite sure. Both Enphase and SolarEdge have some kind of MPPT
(Maximum Power Point Tracking) circuit, which what you're describing.
However, the SolarEdge device outputs DC and requires an external DC
to AC inverter, while the Enphase outputs AC directly. I would guess
this was done to avoid patent debates. Since both have MPPT
circuitry, I would consider both to be "optimizers". Since the
inverter is external in the SolarEdge system, they could not be called
"micro-inverters". I guess "optimizer" is an adequate description.

E.g., my Enphase micro-inverter roof puts out 60Hz 230Vac,
up to 12 amps per section, and 37A max total. But if the
230Vac line source is removed, all microinverters cease to
function, and the system is OFF. It's possible an optimizer
system will still try to maintain 600 to 800 V at its output.

I don't know which model SolarEdge "optimizer" Tesla may or may not be
using at Walmart and Amazon. Skimming the data sheets, I selected:
<https://www.solaredge.com/sites/default/files/se-P5-series-commercial-add-on-frame-mounted-power-optimizer-datasheet-na.pdf>
as a likely device.
"OUTPUT DURING OPERATION (POWER OPTIMIZER CONNECTED TO
OPERATING SOLAREDGE INVERTER) 85V or 15A DC"

Also from the data sheet, the SolarEdge devices go to 1V output with
the "POWER OPTIMIZER DISCONNECTED FROM SOLAREDGE INVERTER OR SOLAREDGE
INVERTER OFF".

MC4 connectors:
<https://www.solaredge.com/sites/default/files/se_branch_cables_datasheet.pdf>
<https://en.wikipedia.org/wiki/MC4_connector>
<https://www.google.com/search?q=mc4+connector&tbm=isch>

MC4 Y-branch connector failure video:
<https://www.youtube.com/watch?v=DQtdbrxC7oU>


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jasen Betts]

On 2019-08-27, jlarkin@highlandsniptechnology.com <jlarkin@highlandsniptechnology.com> wrote:

https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

0.25mΊ contact resistance gives about 1W heating at 65A

--
When I tried casting out nines I made a hash of it.

 

[Robert Baer]

jlarkin@highlandsniptechnology.com wrote:

https://www.zerohedge.com/news/2019-08-23/teslas-secret-spontaneously-combusting-solar-panel-cover-0

https://www.bloomberg.com/news/articles/2019-08-23/amazon-joins-walmart-in-saying-tesla-solar-panels-caught-fire

That H4 connector looks pretty dinky to be rated for 65 amps.

http://www.amphenol-industrial.com/h4-pv-connector

Are you joking?
"Amphenol Industrial Solar Technologies’ H4 PV Connector is the
premiere solar connector in the market today. Carries more amps than the
industry standard connector. Meets the NEC 2008/2011 standard “as is” no
additional locking-clip required. Available in four different gauges:
31A(2.5mm2, AWG14), 42A(4.0mm2, AWG12), 53A(6.0mm2, AWG10), 65A(10.0mm2,
AWG8)."

I would rate AWG 8 at 16.5A max.
NEC gives 40A.
Both ratings a far cry from 65A; maybe they get their balls from IRC
FETs.

 

[Winfield Hill]

Robert Baer wrote...

"Amphenol Industrial Solar Technologies (tm) H4
PV Connector is the premiere solar connector in
the market today. Carries more amps ...

The M4-type connectors generally come pre-molded
from the PV panel companies and the optimizer /
micro-inverter companies, so installers simply
plug them together. A special tool is required
to unplug them. They look and feel quite rugged.
But images of the contacts look very wimpy.

Supposedly optimizers shut off panel output, if
the inverter is off or disconnected. However
there are stories of shut-off cables sparking.

A series string of panels with M4 connectors
is simply one wire, carrying DC current, yet
supposedly the inverter somehow controls all
the optimizers. I couldn't find out how it
does that, or how reliable that scheme is.
There may be an issue of shorted MOSFETs.

In the case of the micro-inverters on my roof,
one per panel, they require 230Vac to run, so
disconnection is a good on/off control method.
But micro-inverter systems cost about $50 to
$100 more per panel than optimizer systems.


--
Thanks,
- Win

 

[Rick C]

On Wednesday, August 28, 2019 at 11:30:38 AM UTC-4, Winfield Hill wrote:

Robert Baer wrote...

"Amphenol Industrial Solar Technologies (tm) H4
PV Connector is the premiere solar connector in
the market today. Carries more amps ...

The M4-type connectors generally come pre-molded
from the PV panel companies and the optimizer /
micro-inverter companies, so installers simply
plug them together. A special tool is required
to unplug them. They look and feel quite rugged.
But images of the contacts look very wimpy.

Supposedly optimizers shut off panel output, if
the inverter is off or disconnected. However
there are stories of shut-off cables sparking.

A series string of panels with M4 connectors
is simply one wire, carrying DC current, yet
supposedly the inverter somehow controls all
the optimizers. I couldn't find out how it
does that, or how reliable that scheme is.
There may be an issue of shorted MOSFETs.

In the case of the micro-inverters on my roof,
one per panel, they require 230Vac to run, so
disconnection is a good on/off control method.
But micro-inverter systems cost about $50 to
$100 more per panel than optimizer systems.

Perhaps you can explain what you think optimizers do and how they are used in the system. I'm not following what you seem to be saying. Are you suggesting there is more than one optimizer per inverter? I'm surprised there are separate optimizers and inverters.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Winfield Hill]

Rick C wrote...

Perhaps you can explain what you think optimizers do ...

Every panel has its own optimizer (OK, now they
have dual optimizer boxes, four wires, two panels
each.) Current must be the same in all optimizers
in series. The optimizers control their output
voltage, to match their panel's available MPPT
power: low power low voltage, high power, higher
voltage. An additional trick is that SolarEdge
optimizers somehow control all the optimizers,
so total series voltage is fixed, e.g., 400V. I
wonder a) how they do that, and b) failure modes.


--
Thanks,
- Win

 

[Rick C]

On Wednesday, August 28, 2019 at 9:30:10 PM UTC-4, Winfield Hill wrote:

Rick C wrote...

Perhaps you can explain what you think optimizers do ...

Every panel has its own optimizer (OK, now they
have dual optimizer boxes, four wires, two panels
each.) Current must be the same in all optimizers
in series. The optimizers control their output
voltage, to match their panel's available MPPT
power: low power low voltage, high power, higher
voltage. An additional trick is that SolarEdge
optimizers somehow control all the optimizers,
so total series voltage is fixed, e.g., 400V. I
wonder a) how they do that, and b) failure modes.

If the current in all panels in series is equal, how can each panel be "optimized" separately??? I guess I've been thinking the current through the string to the inverter would pass through all the cells. But the reality is the optimizer isolates the cells of a panel from the output current so panels in series run at the same current, but the cells of each panel run at different current from other panels?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209