Sol-ark 15K failover / bypass transfer switch

[NopeNobody]

Hello,

Apologies if this has been discussed before and I missed it. If something goes wrong with sol-ark 15K (e.g. a chip/capacitor on one of the boards break) -- does it have a failover / way you can run the grid only without solar that is entirely independent to electronics? If so, can anyone point me to what this is called or where it exists in their documentation.

Thanks

 

[2TrevorJ]

In standby mode it'll pass through but if there's a fault pass through functionality depends on the type/severity of the fault. They said that if the fault is with the AC side of the inverter that pass through will likely not be active.

sol-ark 15 question (bypass wiring)

I'm investigating a system that can switch between being off grid and being on grid via a transfer switch I was looking at the sol-ark manual, and where they show a bypass, even in off-grid mode it looks like its still asking for power from the grid. am I reading this correctly, and if so, why...

diysolarforum.com

 

[NopeNobody]

In standby mode it'll pass through but if there's a fault pass through functionality depends on the type/severity of the fault. They said that if the fault is with the AC side of the inverter that pass through will likely not be active.

sol-ark 15 question (bypass wiring)

I'm investigating a system that can switch between being off grid and being on grid via a transfer switch I was looking at the sol-ark manual, and where they show a bypass, even in off-grid mode it looks like its still asking for power from the grid. am I reading this correctly, and if so, why...

diysolarforum.com

Appreciate quick response.

Seems like advisable answer is using the bypass transfer switch for those who plan to keep grid as an option. This option ensures sol-ark can't be single point of failure. There is a diagram / wiring guide for this in the sol-ark 15K guide.

In case anyone else comes along and see this, thread below (and specifically post on engineer youtube video) discusses GE 200 amp double throw transfer switch. https://diysolarforum.com/threads/sol-ark-15-question-bypass-wiring.54662/

Also another good thread on the topic is here: https://diysolarforum.com/threads/sol-ark-15k-pass-through-when-off.49403/

https://www.sol-ark.com/wp-content/uploads/15K-2P_Manual.pdf (page 9, diagram with bypass transfer switch)

Example of GE double throw 200 amp transfer switch https://www.homedepot.com/p/GE-200-...ency-Power-Transfer-Switch-TC10324R/100150463

 

[629658]

Use a bypass Sol Ark will not pass through if it has an issue.

 

[robby]

I just cannot imagine anyone putting in an AIO and not having a bypass switch and preferably an automatic one.

 

[Shimmy]

I just cannot imagine anyone putting in an AIO and not having a bypass switch and preferably an automatic one.

A source-selective ATS that bypasses the inverter is fine, but expensive. Personally I am not a fan of it, because you are transferring in a failed state without knowing what caused the fault. The bypass should really be a maintenance tool and not something to hopefully improve reliability.

 

[robby]

A source-selective ATS that bypasses the inverter is fine, but expensive. Personally I am not a fan of it, because you are transferring in a failed state without knowing what caused the fault. The bypass should really be a maintenance tool and not something to hopefully improve reliability.

You’re right but the chances are kind of slim that the problem is upstream. I would expect either breakers to pop or if it’s a major issue the main breaker should kick out before the ATS is damaged

 

[Shimmy]

You’re right but the chances are kind of slim that the problem is upstream. I would expect either breakers to pop or if it’s a major issue the main breaker should kick out before the ATS is damaged

The danger scenario is usually retransfer to inverter. This is especially true if you have motors running and providing regenerative power back into the inverter. I prefer interlocked (sliding shield vs walking beam) breakers since I can control how long I wait after opening the first breaker to close the second breaker.

I'm not sure how well designed the high frequency inverters are to accommodate the retransfer, but most low frequency units struggle, some to the point of destruction.

 

[Oldphile]

Mine was online from October to late December with PV off (no PTO). Frustrated waiting for PTO, I turned on the PV without grid sell. Within a few days, we had a brief power outage. The Sol-Ark ATS disconnected from the grid, but faulted when the grid came back and did not pass through. I had to power cycle to restore the Sol-Ark. After contacting Sol-Ark, they did a firmware update. It's never failed since and we've had a number of outages. I don't have a manual transfer switch, but do have a standby generator with transfer switch to a critical loads panel. Not ideal, but better than nothing. The generator carried us until I figured out how to reset the Sol-Ark.

Edit; I should have mentioned I don't have batteries yet.

 

[Shimmy]

Mine was online from October to late December with PV off (no PTO). Frustrated waiting for PTO, I turned on the PV without grid sell. Within a few days, we had a brief power outage. The Sol-Ark ATS disconnected from the grid, but faulted when the grid came back and did not pass through. I had to power cycle to restore the Sol-Ark. After contacting Sol-Ark, they did a firmware update. It's never failed since and we've had a number of outages. I don't have a manual transfer switch, but do have a standby generator with transfer switch to a critical loads panel. Not ideal, but better than nothing. The generator carried us until I figured out how to reset the Sol-Ark.

Interesting they were able to address it with a firmware update and it was a resettable fault. Retransfer is always a little tricky and often overlooked in designs.

 

[NopeNobody]

Mine was online from October to late December with PV off (no PTO). Frustrated waiting for PTO, I turned on the PV without grid sell. Within a few days, we had a brief power outage. The Sol-Ark ATS disconnected from the grid, but faulted when the grid came back and did not pass through. I had to power cycle to restore the Sol-Ark. After contacting Sol-Ark, they did a firmware update. It's never failed since and we've had a number of outages. I don't have a manual transfer switch, but do have a standby generator with transfer switch to a critical loads panel. Not ideal, but better than nothing. The generator carried us until I figured out how to reset the Sol-Ark.

Thanks for the follow up.
It’s basically a 1K gamble in my eyes. If you have a path around it like critical loads and genny, it’s much less risk.

I don’t know if it’s possible to engineer a true 100% fail proof manual bypass into the system, but I hope it’s something they introduce in the future (if it is).

 

[Shimmy]

Thanks for the follow up.
It’s basically a 1K gamble in my eyes. If you have a path around it like critical loads and genny, it’s much less risk.

I don’t know if it’s possible to engineer a true 100% fail proof manual bypass into the system, but I hope it’s something they introduce in the future (if it is).

The 100% approach is separate breakers from the utility for your inverter input and bypass, and a bypass switch at the load-side panel. Eliminate taps.

For me, it is three extra 200A Homeline breakers, an interlock shield, and 4' of wire. Well under $1k installed.

 

[Clint-L]

I poor man’s way around this is to keep some multitaps on hand and if the solark fails completely, just kill the main power (assuming you have a main safety disconnect) and then pull the wires from your solark and multitaps them together. It is a sucky thing, but a good backup plan to have if you don’t have the needed selection transfer switch in place. Lol. ?

 

[629658]

I poor man’s way around this is to keep some multitaps on hand and if the solark fails completely, just kill the main power (assuming you have a main safety disconnect) and then pull the wires from your solark and multitaps them together. It is a sucky thing, but a good backup plan to have if you don’t have the needed selection transfer switch in place. Lol. ?

Well that would be one way to do it.

 

[OlderDIYer]

I recently installed a Sol-Ark 12K in my old double wide mobile home. Since I never liked the crowded main panel they put in this home I welcomed the opportunity to install a full sized 40 circuit panel as my critical load panel. Instead of taking the 60 amp feed from the main panel directly into the Sol-Ark I installed a sub panel and fed that. Then added two 60 Amp breakers to that, one to feed the Sol-Ark and one to feed the main breaker of the sub panel. The Sol-Ark output feeds a 60 amp breaker in the lower right corner of the critical load panel as is standard practice. I used this manual bypass system to feed the Critical loads panel before I had the Sol-Ark and while I moved most of the circuits over from the main panel to the newly installed Critical loads panel. Once I received and installed the Sol-Ark it was easy to power down the Critical loads panel, tape off the two breakers feeding it with Grid, and turn on the two breakers feeding it from the Sol-Ark.

After 8 days of running on the Sol-Ark my house went dark at 4 in the morning and it turned out to be a hardware failure of the inverter requiring a replacement unit. If I didn't have the bypass system in place it would have been a worse nightmare than it was so I was so glad I had that in place. Because I was loving what the Sol-Ark was doing for me (free power from the sun!) I ordered a second unit I will install in parallel when I get it for redundancy. Bottom line, make sure you have a Bypass!

 

[Shimmy]

Because I was loving what the Sol-Ark was doing for me (free power from the sun!) I ordered a second unit I will install in parallel when I get it for redundancy.

Be careful with your expectation of redundancy; there are a lot of common-mode failures when paralleling these AIO systems. It is almost better to have a cold backup if you really want redundancy. The other option is a salt-and-pepper system with two independent outputs and a means to tie the output panels together manually.

 

[OlderDIYer]

Be careful with your expectation of redundancy; there are a lot of common-mode failures when paralleling these AIO systems. It is almost better to have a cold backup if you really want redundancy. The other option is a salt-and-pepper system with two independent outputs and a means to tie the output panels together manually.

Thanks for the feedback! I know they both have to share the same battery bank so that's the biggest single failure point I can think of. They don't share the collectors at all. If the master inverter goes out I'd have to move the solar collector wires over to the back up, no problem there. What other potential issues do you see? I thought of "ready to go" setup where I mount and wire and test the second inverter then just turn it off. Would you consider that a cold backup? If so, I agree that sounds like a good option.

As long as the grid is up no failure on the inverter, batteries, or solar panels can keep the house dark with the bypass in place. My original justification for this system was as a backup for an extended grid outage (and liked the idea of a whole house UPS and no messing with a generator). Then I got excited about the solar input to extend range in an outage. And lastly realized I could cut my utility power use with enough solar and battery combination.

It took me less than 4 hours to swap out the box so maybe just leaving it in a closet is a viable option but if I ever needed it it would be untested as a downside.

Of course, to really go to the extreme, I was considering adding the inverter plant in and on the roof of my detached garage (it has a separate utility service). So I could use the second Sol-Ark with another battery bank and solar collector set over there and then tie the two critical load panels together so they can back each other up. That would be about as good as it gets but much more expensive!

Just thinking out loud!

 

[Shimmy]

Thanks for the feedback! I know they both have to share the same battery bank so that's the biggest single failure point I can think of. They don't share the collectors at all. If the master inverter goes out I'd have to move the solar collector wires over to the back up, no problem there. What other potential issues do you see?

It is easy to have an AC output fault that burns out both inverters if they are load sharing. If you have closed loop battery comms that is another risk.

I thought of "ready to go" setup where I mount and wire and test the second inverter then just turn it off. Would you consider that a cold backup? If so, I agree that sounds like a good option.

That's what I meant, yes. Also reduces your efficiency losses.

 

[OlderDIYer]

It is easy to have an AC output fault that burns out both inverters if they are load sharing. If you have closed loop battery comms that is another risk.

That's what I meant, yes. Also reduces your efficiency losses.

Thanks for the feedback. It's too early to decide what to do. Once i get the replacement I'll probably be anxious to mount it, wire it and test it so I'll probably at least try it in parallel and depending on how that goes either leave it that way or shut it down as a cold standby. I'm pretty sure I want to up my battery bank from 25kwh to 45kwh so as to be able to utilize all the solar I'm generating on nice sunny days.

 

[vin2002]

It is easy to have an AC output fault that burns out both inverters if they are load sharing. If you have closed loop battery comms that is another risk.

That's what I meant, yes. Also reduces your efficiency losses.

Hi @Shimmy, can you explain a litle what scenarios might lead to "an AC output fault that burns out both inverters", or how "closed loop comms" are a risk? I should know these things but I don't.

Also regarding uptime of the solar system, I'm OFF grid and have 2 15k's in parallel, so I'm acutely aware of how little thought seems to have gone into "availability" for off grid (I do understand it tho, 99% of their business must be grid tie). A month back Sol-Ark wanted to update the firmware so I asked about de-pairing them, or how you go about a parallel upgrade without down time. According to support there isn't a way. Coming from an IT background running load-sharing firewalls and load balancers I was surprised the firmware didn't allow for this. But packets and amps are pretty different I guess.

I'm trying to finalize the wiring for the bypass now which brought me to this thread. For me the grid is a 22k whole house backup gen that I want to be able to power the house in case the solar system needs an upgrade or work done to it.

Thanks for reading!