Compatibility with SolarEdge Rapid Shutdown Optimizers?

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SoCal Dave
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My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Sat Aug 15, 2020 5:44 pm

I have a newly installed 12.24kW system from Tesla. It has 3 strings feeding a SolarEdge SE10000H 10kW Inverter with Rapid Shutdown.

I'm looking at adding the SkyBox for AC coupling and adding batteries to my system. My thought is to take 1 of the strings and feed it into the Skybox instead of the SolarEdge inverter. Is the SkyBox compatible with the SolarEdge Rapid Shutdown system or would I need to add a smaller SolarEdge inverter in the middle?

Ampster
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Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Mon Aug 17, 2020 2:56 pm

SoCal Dave wrote:
Sat Aug 15, 2020 5:44 pm
I have a newly installed 12.24kW system from Tesla. It has 3 strings feeding a SolarEdge SE10000H 10kW Inverter with Rapid Shutdown.
I'm looking at adding the SkyBox for AC coupling and adding batteries to my system. My thought is to take 1 of the strings and feed it into the Skybox instead of the SolarEdge inverter. Is the SkyBox compatible with the SolarEdge Rapid Shutdown system or would I need to add a smaller SolarEdge inverter in the middle?
The rapid shutdown in the Solaredge system is performed by the proprietary Solar Edge Optimizers. I looked into using Tigo Optimizers when I thought I needed RSD for some panels I was installing on a patio cover to power my Skybox. It turns out it was not needed but was going to cost almost $1.000. That is one alternative and I don't know how that compares to the cost of a small Solaredge inverter.

I presume what you are trying to do is reduce the size of your Solaredge system so that it will fit the AC coupling requirement of the Skybox which I believe is somewhere around 7 kW. I presume the idea was to have the smaller inverter wired to your main panel and have the larger system AC coupled through your critical loads panel which is controlled by the Skybox. Or alternately as you suggested have one string going to the Skybox. Have you verified that your jurisdiction requires Phase Two of the RSD requirements? Phase Two, if I understand correctly is panel level shutdown which is native to Solaredge. Phase One is implemented in the Skybox and would only require installing a shutdown swich wired to the RSD terminals of the Skybox.

The additional issue is getting Tesla to do that in order to maintain your additional warranty. I am a Tesla Fanboy but they are not known for their flexibilty on their solar installations.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

Mike Curran
Forum Emperor
Posts: 1797
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Mike Curran » Mon Aug 17, 2020 4:13 pm

FWIW, I had Enphase M215 microinverters equipped PV modules AC coupled to my Skybox and they worked fine that way. They don't have any rapid shutdown capability but if your Solaredge units work as module level shutdown and don't require a Solaredge "downstream interface" (between the module string and its output connection) for it to work, then I don't see why they would not work for you. You would have to wire your RSD actuator switch so that in addition to sending a signal to the Solaredge optimizers to shut down it also opens the RSD circuit on Skybox. https://drive.google.com/file/d/107j7JH ... p=drivesdk
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Mon Aug 17, 2020 9:10 pm

Mike Curran wrote:
Mon Aug 17, 2020 4:13 pm
FWIW, I had Enphase M215 microinverters equipped PV modules AC coupled to my Skybox and they worked fine that way. They don't have any rapid shutdown capability but if your Solaredge units work as module level shutdown and don't require a Solaredge "downstream interface" (between the module string and its output connection) for it to work, then I don't see why they would not work for you. You would have to wire your RSD actuator switch so that in addition to sending a signal to the Solaredge optimizers to shut down it also opens the RSD circuit on Skybox. ......
The Enphase micros and Solaredge Optimizers natively have RSD at the module level.

If I understood the OPs question, it was whether the Solaredge Optimizers would work with the Skybox if he rewired a string from the Solaredge system to his Skybox. I think the answer is no, because they use a powerline communication protocol unique to Solaredge so the Optimizers know that the inverter is off and automatically shutdown. That is what I meant by native RSD. If no powerline signal from the inverter there is no output. Similar with Enphase, if the AC power is gone there is no output at the module level.

The reason he wanted to move a string was that I believe he was up against the maximum GT inverter system that the Skybox can AC couple with.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

Mike Curran
Forum Emperor
Posts: 1797
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Mike Curran » Tue Aug 18, 2020 5:16 am

The Enphase micros and Solaredge Optimizers natively have RSD at the module level.
The M215s don't have an RSD function, they simply disconnect when there's no grid power detected. No way to manually shut them down with a pushbutton like later models can.
If I understood the OPs question, it was whether the Solaredge Optimizers would work with the Skybox if he rewired a string from the Solaredge system to his Skybox. I think the answer is no, because they use a powerline communication protocol unique to Solaredge so the Optimizers know that the inverter is off and automatically shutdown. 
So this means they must have a Solaredge inverter at their output. I guess I thought they were microinverters that didn't require a string inverter. That's how the Enphase units work, no string inverter needed, they are each their own "microinverter".
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Tue Aug 18, 2020 1:50 pm

Thanks for the responses all.

I've wondered about the warranty. The agreement from Tesla doesn't prohibit changes as long as they are in compliance with the "Owner's Manuel(s)". Now them not giving me a hassle if I've completely redesigned the system is a different story.

Warranty Exclusions. The “Workmanship” warranty above does not cover any defect caused by (1) events
beyond our reasonable control, including but not limited to lightning, flood, earthquake, fire, excessive wind and other
extreme weather events, accidents, abuse, misuse or negligence; (2) your failure to operate or maintain your Products in
accordance with the applicable Owner’s Manual(s); (3) strikes by balls or other objects, dirt, dust, bird excrement, animals,
insects, foliage or algae growth; (4) roof leaks caused by ordinary wear and tear, or water entering around a fitting,
accessory or other material not installed by Tesla; (5) any material or equipment connected to your Products that was not
installed by us; or (6) someone other than Tesla installing, altering, removing, re-installing or repairing any part of your
system unless that person does so in compliance with the Owner’s Manual(s).


Below are some drawings of what I'm trying to do. The first is my current setup.
https://postimg.cc/t7gqhhKH

This shows what I'm planning. My question is if I need the orange box which represents another SolarEdge Inverter. Based on the comments here it sounds like I would.
https://postimg.cc/Lh0HvJSg

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Tue Aug 18, 2020 1:55 pm

Also, if anyone has an easier and/or more cost effective way to achieve what I'm looking for, I'd love to hear it.

I'm basically looking for having some outage protection for critical loads without breaking the bank. Power outages are very rare in my area, so I'm not looking at 3 Powerwalls at $24,000 or something crazy like that. Financially, a small generator seems to be the most financially practical, but I would love to leverage my solar panels if reasonably possible.

I used to be an electrician so I can do the installation myself.

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Tue Aug 18, 2020 2:25 pm

SoCal Dave wrote:
Tue Aug 18, 2020 1:55 pm
Also, if anyone has an easier and/or more cost effective way to achieve what I'm looking for, I'd love to hear it.
.........
It depends if you need the panel level shutdown in what I call Phase Two of that RSD requirement. Only your local building department can tell you. It will determine what your options are.

The only input I have at this point on the second diagram is that the solar that you want AC coupled needs to go through a breaker on the critical loads panel. The new inverter (Orange Box) would go to to critical loads panel and only it would work when grid is down. The RSD on the Skybox would shut down the Skybox which would drop the new inverter and the native panel level shutdown of the Solaredge would shut the panels connected to that inverter.
The only way to save money would be if you don't need panel level shut down and you could avoid the cost of a new inverter. But you would have to remove the Optimizers on that string because they will not operate with the Skybox, that means a trip to the roof and and that may not be worth the trade off. The only other thing to check is the specs of your panels to see if their minimum startup voltage in a string of 7 is enough to start the Skybox solar production. I couldn't tell what the voltage of your panels were from the total kWh of your solar panels. I thought I read somewhere that each string was 7 but I reread the thread and that may not be correct assumption.

Does that make sense?
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Wed Aug 19, 2020 4:44 pm

Ampster wrote:
Tue Aug 18, 2020 2:25 pm
SoCal Dave wrote:
Tue Aug 18, 2020 1:55 pm
Also, if anyone has an easier and/or more cost effective way to achieve what I'm looking for, I'd love to hear it.
.........
It depends if you need the panel level shutdown in what I call Phase Two of that RSD requirement. Only your local building department can tell you. It will determine what your options are.

The only input I have at this point on the second diagram is that the solar that you want AC coupled needs to go through a breaker on the critical loads panel. The new inverter (Orange Box) would go to to critical loads panel and only it would work when grid is down. The RSD on the Skybox would shut down the Skybox which would drop the new inverter and the native panel level shutdown of the Solaredge would shut the panels connected to that inverter.
The only way to save money would be if you don't need panel level shut down and you could avoid the cost of a new inverter. But you would have to remove the Optimizers on that string because they will not operate with the Skybox, that means a trip to the roof and and that may not be worth the trade off. The only other thing to check is the specs of your panels to see if their minimum startup voltage in a string of 7 is enough to start the Skybox solar production. I couldn't tell what the voltage of your panels were from the total kWh of your solar panels. I thought I read somewhere that each string was 7 but I reread the thread and that may not be correct assumption.

Does that make sense?
Thanks again for the reply.

I definitely don't want to remove the optimizers.

I thought I remembered reading the AC coupling from the Skybox could drive an inverter. I guess I must have misunderstood that. I wouldn't want the inverter only on the critical loads panel.

For my system, it seems the Tesla Gateway would be best. Shame a homeowner can't buy one.

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Wed Aug 19, 2020 9:24 pm

SoCal Dave wrote:
Wed Aug 19, 2020 4:44 pm

I definitely don't want to remove the optimizers.

I thought I remembered reading the AC coupling from the Skybox could drive an inverter. I guess I must have misunderstood that. I wouldn't want the inverter only on the critical loads panel.

For my system, it seems the Tesla Gateway would be best. Shame a homeowner can't buy one.
The Tesla Gateway is a transfer switch and some Current measurement equipment which would not do much to help you AC couple. It would be an expensive transfer switch because all the communication with Tesla built into it would have not purpose without the inverter and batteries in the Powerwall.
You are correct the Skybox can drive a GT inverter but the only port to get that from is the same port that is connected to the critical loads panel. That is how mine is connected and the power is still exported to the grid. I initially had the same thought about not wanting the GT inverter on the critical loads panel but thinking it through I would have lost all the automatic functionality and there is no negative to having it there. Is there something I am missing about why you do not want it there?

So if you don't want to remove the Optimizers your choice is to get another Solaredge inverter and wire one of your inverters to the critical loads panel and the other one to the main panel.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Sat Aug 22, 2020 3:05 pm

@SoCal Dave
I haven't heard back from you. I just want to make sure that you understand that Solaredge inverters are capable of AC coupling to a Skybox. My feedback was not about the compatibility of the Optimizers.

My suggestion about the critical loads panel is how any AC coupling scenerio would be wired to almost any hybrid inverter. Also the Skybox is limited to 7.6 of Solar that can be coupled so some down rating or other workaround is all that would have to be done to AC couple to a Skybox.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

Mike Curran
Forum Emperor
Posts: 1797
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Mike Curran » Sat Aug 22, 2020 3:41 pm

@Ampster: If the OP wants to AC couple a portion of his existing array with optimizers to the Skybox, it should work. I believe the incompatibility Skybox has with optimizers is only if they are on the array modules connected to the Skybox PV input, not those AC coupled to the critical loads/AC output connection. Please correct me if I'm wrong.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Sat Aug 22, 2020 8:34 pm

Mike Curran wrote:
Sat Aug 22, 2020 3:41 pm
@Ampster: If the OP wants to AC couple a portion of his existing array with optimizers to the Skybox, it should work. I believe the incompatibility Skybox has with optimizers is only if they are on the array modules connected to the Skybox PV input, not those AC coupled to the critical loads/AC output connection. Please correct me if I'm wrong.
I will go one step further and tell you that you are correct and that is what I wanted to convey to the OP. Because of the limit in the Skybox he would only be able to use maybe two of his strings with his existing inverter. In other words he would have to derate that inverter and connect the other string to a smaller inverter that could not be powered by the Skybox.It could be connected to the main panel and would produce energy when the grid was up and working.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Mon Aug 24, 2020 10:49 am

Ah, I was thinking if the SolarEdge inverter was in the critical loads panel there wouldn't be AC coupling. But, now I get from the SolarEdge inverter's perspective all it would see is available power and wouldn't know there isn't power from the grid. I assume the Skybox has no issue with power being generated from the critical loads panel?

My only desire in not having the extra SolarEdge inverter is just a cost issue. This solution is getting a bit pricey once I include all the components.

OutBack Skybox - $3,328
SolarEdge 5kW Inverter - $1,420
20kWh Lead Acid Battery Bank (not sure on the battery solution I would actually select) - $2,859
Critical Load Panel - $47.28
PV/Battery Feed Panel (for single Rapid Shutdown Disconnect) - $47.28
Rapid Shutdown Disconnect - $109.95
Wiring gutters - $300
Misc conduit, wire, pipe fittings, etc. - $500
Total - $8,611.51

I'm not following your comments on the Tesla Gateway. My understanding is it offers AC coupling to the inverters connected to it.

I understand this sub system would not alter the behavior of the original SolarEdge inverter and the 2 strings tied to that. If there was a power loss that inverter would turn off as it does today. When OutBack supports AC coupling with multiple Skyboxes, it might make more sense to have 2 Skyboxes for my single 10kW SolarEdge inverter so the entire system is AC coupled.

Mike Curran
Forum Emperor
Posts: 1797
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Mike Curran » Mon Aug 24, 2020 12:18 pm

I assume the Skybox has no issue with power being generated from the critical loads panel?
Yup, that's what AC coupling is and what Skybox has provision for.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Mon Aug 24, 2020 3:11 pm

Mike Curran wrote:
Mon Aug 24, 2020 12:18 pm
I assume the Skybox has no issue with power being generated from the critical loads panel?
Yup, that's what AC coupling is and what Skybox has provision for.
Thanks for the confirmation Mike

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Mon Aug 24, 2020 4:03 pm

SoCal Dave wrote:
Mon Aug 24, 2020 10:49 am
Ah, I was thinking if the SolarEdge inverter was in the critical loads panel there wouldn't be AC coupling. But, now I get from the SolarEdge inverter's perspective all it would see is available power and wouldn't know there isn't power from the grid. I assume the Skybox has no issue with power being generated from the critical loads panel?
The Skybox has to see the Solaredge inverter's power because it has to be able to measure it when the grid is down. When the batteries are full and there is no charging load and when the house load fluctuates the Skybox has to be able to modulate the Solaredge otherwise the Solaredge would invert all the power that the solar panels were sending to it. That is also why there is a 7kW limit on the amount of GT power that the Skybox can effectively handle.
My only desire in not having the extra SolarEdge inverter is just a cost issue. This solution is getting a bit pricey once I include all the components.

OutBack Skybox - $3,328
SolarEdge 5kW Inverter - $1,420
20kWh Lead Acid Battery Bank (not sure on the battery solution I would actually select) - $2,859
Critical Load Panel - $47.28
PV/Battery Feed Panel (for single Rapid Shutdown Disconnect) - $47.28
Rapid Shutdown Disconnect - $109.95
Wiring gutters - $300
Misc conduit, wire, pipe fittings, etc. - $500
Total - $8,611.51
Those are reasonable costs based on my installation. The only cost saving might be to reduce the size of the second Solaredge inverter to 3.8 kW as long as it did not exceed Solaredge's DC to AC recommendation of 1.50 to 1. I don't recall the exact DC size of your strings to know if that is practical. Batteries are another area that I discuss below.
I'm not following your comments on the Tesla Gateway. My understanding is it offers AC coupling to the inverters connected to it.
The Tesla Gateway is just a 200 Amp electronically controlled switch, some CTs and electronics in an enclosure separate from the Powerwall. The Powerwall contains the batteries and the inverter that gets the data from the CTs and the electronics and provides the simulated grid signal that actually does the AC coupling. A complete Powerwall installation would cost more than your numbers above and would be limited to 13kwh of battery storage. To add another 13 kWh of storage would take another complete Powerwall but you would not need another Gateway so you would save a some on a second Powerwall.

I actually had a deposit on a Powerwall when there were still rebates. After analyzing my loads and my needs during an extended outage I elected to go with the Skybox back when it cost over $6000 because I wanted upgrade my battery capacity at a less expensive increment. I just added 28 kWh of LFP batteries for $3500. Battery cost might be an area of cost savings if you wanted to go with another chemistry.
I understand this sub system would not alter the behavior of the original SolarEdge inverter and the 2 strings tied to that. If there was a power loss that inverter would turn off as it does today. When OutBack supports AC coupling with multiple Skyboxes, it might make more sense to have 2 Skyboxes for my single 10kW SolarEdge inverter so the entire system is AC coupled.
That is certainly an option for the future. Again I do not know the exact capacity of each string but an interim alternative assuming 2 strings would derate enough to meet the maximum Skybox AC coupling is to AC couple the big inverter with two strings to the Skybox and have the smaller one just be grid tied. It is not the GT inverter capacity that is the limiting factor, it is the potential output that is the limiting factor. I may not have used the term derating correctly but what I mean would be to run it at a DC to AC ratio below 1 to 1 because only two strings were connected. None of the suggestion in this paragraph would save any money it would just get you a little more power during an grid down situation.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

SoCal Dave
Forum Member
Posts: 7
Joined: Sat Aug 15, 2020 5:14 pm
My RE system: 12.24 kW solar panels with SolarEdge 10kW inverter

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by SoCal Dave » Mon Aug 24, 2020 4:35 pm

Ampster wrote:
Mon Aug 24, 2020 4:03 pm
I just added 28 kWh of LFP batteries for $3500. Battery cost might be an area of cost savings if you wanted to go with another chemistry.
Appreciate the detailed response. If you don't mind me asking, where did you get the batteries from? Also, do you have an enclosure for them?

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Compatibility with SolarEdge Rapid Shutdown Optimizers?

Post by Ampster » Tue Aug 25, 2020 8:16 am

I got the batteries from a seller on Alibaba. I had never considered them until May when I joined diysolarforum.com and discovered how many people had sucessfully purchase LiFePO4 batteries. There are a number of threads with at least four respected vendors that have track records of successful deliveries of product.
I am currently not using a NEMA enclosure and waiting to see my if my building inspector will approve my metal cabinet or if they want to see a full NEMA enclolsure. There is also a new fire code that may limit the amount to Lithium batteries to 20kWh inside a structure. I don't know how and where it has been implemented in my county.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

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