Adding Schneider XW Pro

[Hedges]

Do you agree with the claim in that article that keeping DC voltages under 80VDC is one way to avoid any concern with arc faults?

Never say never, but it should reduce it.

 

[GXMnow]

RSD is for the safety of firemen. I do want to have that functional. I was hoping the Midnite Solar charge controller produced the keep alive signal, but it seems that it does not. If I go the Tigo route, I would power the keep alive transmitter from one of the breakers in my Enphase solar combiner. That way, the one disconnect for the Enphase will also shut off the DC panels. IT would be great to also have an ARC fault trip off the Tigo RSD boxes. I looked at the latest online manual for the Midnite Solar Classic and it does have a function where an array ground fault can trip the aux relay, but no mention of Arc Fault in the aux relay section.

Midnite does offer their Modbus Map, and there is a location 0x00040000 "Arc Fault Occurred If Set". I could have my PLC monitor that and use one of the relay outputs to also cut power to the RSD keep alive transmitter. Location 0x00010000 sets if there is a ground fault. With the length of the address, I think these are bits in a 32 bit register.

Here is the link to the online PDF

https://www.midnitesolar.com/pdfs/classic_register_map_Rev-C5-December-8-2013.pdf

It does appear to be from 2013.

The more normal addresses look like this
4119 Watts
4121 PV input current

I can't find simple PV volts or Battery Volts. IT has peak reach, total KWH per day. The layout is odd.

 

[400bird]

4115 and 4116 look like 1 second average battery and PV voltage to me.
The modbus map was another plus for the Midnight, it should integrate well considering I'm already using modbus.

 

[ChrisG]

I thought the Schneider SCC can detect both arch and ground faults and integrate with the Schneider RSD solution that then is integrated with Tigo. I may be talking nonsense but I believe that is what I read a month ago on the solution.

 

[400bird]

I thought the Schneider SCC can detect both arch and ground faults and integrate with the Schneider RSD solution that then is integrated with Tigo. I may be talking nonsense but I believe that is what I read a month ago on the solution.

The charge controller doesn't have that integration. It's in a separate module, MPPT Disconnect RS. That alone retails in the $700 range.

MPPT Disconnect RS

El MPPT Disconnect RS es un accesorio para los controladores de carga Conext™ MPPT, que proporciona un cumplimiento simplificado del NEC 2017.

solar.se.com

 

[Shimmy]

RSD is for the safety of firemen.

True, but the ability to drop the module voltage is also useful for arc fault protection, hence the value of integrating ground fault and arc fault into the RSD. I just think it is silly that the charge controller can't integrate that functionality for much less than the $700 Schneider charges for the MPPT-RSD.

 

[pvdude]

Preparing and collecting components for Winter 22-23 projects!
Ordered the Conext MPPT 100 600: 6kW Solar PV Charge Controller to run the new PV strings.

Looked at the Q.PEAK DUO XL-G10.3 / BFG 480 watt, but don't have room for them on the shop roof. (87" - too long to fit under the existing)

Plan "B": collecting quotes for 16 of these, as they are 75" long, and thus will overhang the roof edge only 2"
The local Rexel.com has them, a 20 mile drive.

Also replacing the 17 year old AO Smith electric water heater (5kw load) with a
"Heat pump" water heater.
The ancient AO Smith still works perfectly, but "time and technology march on"

 

[mnd]

True, but the ability to drop the module voltage is also useful for arc fault protection, hence the value of integrating ground fault and arc fault into the RSD. I just think it is silly that the charge controller can't integrate that functionality for much less than the $700 Schneider charges for the MPPT-RSD.

I was a bit sticker shocked at the RSD but after installing mine and having a look inside there is a bunch of stuff going on and it would be difficult to duplicate all the functionality and level of integration at the price point.

My only problem with the RSD is that I can't seem to assign a unique Xanbus ID to mine, but both show up just fine in Insight.

 

[ChrisG]

I was a bit sticker shocked at the RSD but after installing mine and having a look inside there is a bunch of stuff going on and it would be difficult to duplicate all the functionality and level of integration at the price point.

My only problem with the RSD is that I can't seem to assign a unique Xanbus ID to mine, but both show up just fine in Insight.

So this is awesome. Confirmation that the RSD actually works well for ground/arch. Quick question, with remote switch/button this will shutdown both the panels and inverter?

 

[mnd]

So this is awesome. Confirmation that the RSD actually works well for ground/arch. Quick question, with remote switch/button this will shutdown both the panels and inverter?

The remote initiator shuts down everything. The local disconnect just breaks connection to the PV.

 

[400bird]

I ran into my first stumble working on the permit last night.
The Tigo RSD modules have a 500 watt limit.
I'll be well under both the voltage and current limits. But they list the 500 watt limit without any clarification (STC, NTC...)
My panels are 480 watt STC, for the front side. With the rear theat pushes them over 500.

I started looking at other options. AP systems does offer RSD but, they are few and far between. I can't find a vendor with both the panel electronics and transmitter in stock and I haven't seen any feedback on their use at all.

I just remembered Arizona Wind and Sun. It appears they list the components,m and make it look like they're in stock.

 

[Hedges]

The actual limit of such a device is likely not watts, rather Volts, Amps, and some complicated equation related to voltage conversion taking place inside it. Possibly the 500 watt limit is valid at a particular Vmp. If it was an optimizer, it would have many more operating points. If just an RSD, it either delivers near-zero volts in shutdown (SolarEdge outputs 1V per panel), or it delivers whatever voltage and current the panel produces.

As far as permits, any review would look at 480W spec.

Here's a 1-channel 700W Tigo:

Tigo TS4-A-F

The TS4-A-F enables cost effective rapid shutdown functionality in a 1 module to 1 TS4 configuration. The TS4-A-F is both IEC and UL certified for global acceptance. The TS4-A-F is UL PV Rapid Shutdown System (PVRSS) certified with hundreds of inverters to comply with NEC 2014, 2017, and 2020...

www.tigoenergy.com

https://assets-global.website-files.com/5fad551d7419c7a0e9e4aba4/631bb8c38d31f53701ce1335_TS4-A-F%20(700W)%20(15A%20and%2025A)%20(Fire%20Safety%20Add-on)%20Datasheet%20EN.pdf

(same current specs as the following?


This one says 2 channel 500W each, but that's at 15A. Allows 700W each with 20A Imp/ 25A Isc.
Unless your panels are high current, probably falls under the 500W limit.

TS4-A-2F, Tigo's newest rapid shutdown solution for commercial rooftops

www.tigoenergy.com

https://assets-global.website-files.com/5fad551d7419c7a0e9e4aba4/631a8861dec2553614e31baf_TS4-A-2F%20(700W)%20(15A%20and%2025A)%20(ire%20Safety%20Add-on%20for%202%20Modules)%20Datasheet%20EN.pdf

500W at 15A Imp = 33.3V Vmp.
700W at 20A Imp = 35V Vmp

Up to 80 Voc allowed.
They seem to be saying more Imp current is allowed, up to 20A, but not more Vmp. Wonder why, since Voc ought to be the limit.
Does it really accept 500W at 7.5A, 66.6V? But not 600W at that voltage?

 

[400bird]

Interesting, my concern was not about the possible failure. After all the 480 watt panel is more likely to produce 400 watts that 500 in actual use.

I am concerned about not passing inspection/getting the permits approved. In my searching I didn't find the 700 watt option. I'll start searching to see if it is commercially available.

 

[Hedges]

For both the models I linked, it was just a different operating point of same RSD box. For higher current PV panel.
Possibly two (smaller) panels paralleled would work for that; not sure the latest RSD rules limit watts just volts.
But your large panels, 2 paralleled, would be way over watts limit of this RSD model.

I think inspection and permits will depend on rated watts of panel. Which is based on front side, not backside.

 

[Shimmy]

They seem to be saying more Imp current is allowed, up to 20A, but not more Vmp. Wonder why, since Voc ought to be the limit.

Aren't they essentially resistors acting as a voltage divider that shunt the panel? That would limit the maximum input voltage to ensure code-compliant output voltage.

 

[Shimmy]

Looked at the Q.PEAK DUO XL-G10.3 / BFG 480 watt, but don't have room for them on the shop roof. (87" - too long to fit under the existing)
Plan "B": collecting quotes for 16 of these, as they are 75" long, and thus will overhang the roof edge only 2"

Or extend the shed overhang by a foot or so...

The ancient AO Smith still works perfectly, but "time and technology march on"

Might want to keep the old AO Smith as a backup/storage tank in series with the heat pump water heater. "They don't make them like they used to." Just add the isolation valves to be able to take either one out of service easily.

 

[Hedges]

It is possible they open-circuit a transistor and use a resistor divider. More likely I think it is a "buck" DC/DC converter, dropping Voc to ~ 1V at lower current. Or just FET switch to connect full current + bypass diode or FET.

Actual limits of the device would be voltage, current, and internal power dissipation.

 

[pvdude]

Might want to keep the old AO Smith

Very conflicted about replacing a working water heater w/ no moving parts, reliable as an anvil, w/ new weird science.
Might just leave it for now, and see how the upgraded solar handles the added 5kw load of the old water heater.
Water heater is on a timer, the heating elements go on once a day. Don't really need that much hot water, except on wash day.
Only two of us living here now, children grew up moved away years ago. (noticed a great reduction in energy usage!)
The existing water heater is wired for "Non-simultaneous" operation.
If I replaced it with another no-tech unit wired for "Simultaneous" operation,
it would draw about 9-10kw (both 4500 watt elements on), but for a much shorter interval.

 

[Hedges]

You can also rewire elements for only one on, or two in series. Or 120V. (lower wattage.)

 

[Rennit]

Also replacing the 17 year old AO Smith electric water heater (5kw load) with a
"Heat pump" water heater.
The ancient AO Smith still works perfectly, but "time and technology march on"

I saw you already posted in my thread about these AO Smith hybrid water heaters. I would really recommend you try another brand. I have heard good things about the Rheem hybrids from word of mouth.