Sol-Ark - Disconnect Strategy?

solardad

Solar Addict
I think I have ironed out a disconnect / safety strategy with my hybrid setup, Sol-Ark 12k.
Goal is to trigger a relay via BMS (Batrium) when either cell voltage is too high, low or a single cell starts to fail based on relative voltage delta.

Today my system is setup to do "grid zero" via limited to home as long as I have PV / Bat. capacity to meet my household loads and if loads exceed system setup then the grid supplies the short fall.

The challenge is two fold after confirming with Sol-Ark

1 - Damaging the inverter if you disconnect the battery under a load. Sol-Ark confirmed that using a relay to disconnect the battery is a "no no". If there is any significant load (they are unable to define significant) then having an emergency disconnect (breaker) could damage the inverter.

2 - The built in RSD relay is only for PV (mppt controllers) and does not shut down the inverter. I was hoping it would shut down everything but the main purpose is to just meet 2017 code for panel level shutdown.

Soo here is my thinking on how to tackle the scenarios...

1. High voltage scenario or Large cell voltage delta -need to stop any charging taking place so I would leverage RSD via relay from the BMS. This would kill any charge and allow the batteries to drain down with existing loads. I would have to manually reset the RSD though I think (Sol-Ark was not clear on how to reset).

2. Low voltage scenario or Large cell voltage delta - 4 pole shunt trip breaker (ex. ABB s5n) on the AC side. This scenario would also require a manual reset but it would kill any inverter demand and as such allow the batteries to charge if there is PV.

I think I am covered and outside of the inverter failing the high and low scenario should never take place given the limits I have set within the inverter. The real benefit or coverage would be for a large cell delta.

Thoughts?

What are others doing given the Sol-Ark limits?

Thanks
 

anadiner

Solar Enthusiast
Note: some of this all depends on where u live. IE) disconnect requirement established after a fire dept refused to put out a fire because was no absolute means to turn off the solar electricity.

So now, many places do not care about an inverter being damaged. They want to see a big OFF switch at the batteries.
 

solardad

Solar Addict
Agree. This is a post install item in that my system has already been approved and in place as is. I have a ground mount so no panel level shut down is required in my area.
 

Mcgivor

Solar Addict
There may be ways to cut charging by using the remote temperature sensor input, a fixed resistance to simulate 25°C run over a normally open contact of a relay driven by the BMS, this would put the SCC in an out of parameter condition, thus shutting down charging ,this method depends on the model of SCC used, Morningstar support endorses this as a means to achieve charging shutdown with their controllers, it may work with others. With Schneider SCC's it is possible to achieve the same results using the PV ground fault circuitry, fooling the controller into believing there is a ground fault, this is not endorsed by Schneider, the RTS method may also work

Having the SCC settings slightly below maximum battery voltage would reduce the chance of a single cell runaway in the first place, but having a secondary means would prevent overcharging should a MOSFET fail in a short condition.

To cut the inverter output what I use is my main distribution breaker, which is a residual current circuit breaker (RCBO ) or " ground fault " type, a resistor connected over a normally closed contact of the same relay used to kill charging, this leaks enough current, >30mA to ground thus tripping the breaker, this doesn't shut down the inverter but if used in conjunction with the DC disconnect, would prevent damaging the inverter as both input and output are disconnected similtaniously.

There may be other ways of inducing a fault to allow a safe shutdown, in both SCC and inverters, often the best place to start is in the fault section of the trouble shooting section of the manual, then simulating a fault.

The point of this post, which may not be directly related to your particular equipment, it is however aimed at thinking outside the box, using available methods in an unconventional way, consider this as a collection of thoughts, nothing more.
 

solardad

Solar Addict
To cut the inverter output what I use is my main distribution breaker, which is a residual current circuit breaker (RCBO ) or " ground fault " type, a resistor connected over a normally closed contact of the same relay used to kill charging, this leaks enough current, >30mA to ground thus tripping the breaker, this doesn't shut down the inverter but if used in conjunction with the DC disconnect, would prevent damaging the inverter as both input and output are disconnected similtaniously.

Thanks for the suggestion.
 

audreez

New Member
i made my batrium talk to sol-ark via canbus and solark listens to it (sol-ark doesnt talk back or batrium doesnt understand it) if you want this let me know i might do a small write up.

other problem that you have with shunt trip (i had the same problem) but im jsut adding 5kw battery that i had from before in front of it (shunt trip breaker) with its own bms so if batrium trips the shunt sol-ark still has some battery and wont have a heart attack (extra battery is not mounted yet on the floor)

as im adding more 280ish amp packs im planning on adding the victron distributor thing with fuses for each 16x pack

(pardon the mess was moving stuff around lately and its temporary permanent work in progress)
 

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coolwaterxii

Solar Enthusiast
i made my batrium talk to sol-ark via canbus and solark listens to it (sol-ark doesnt talk back or batrium doesnt understand it) if you want this let me know i might do a small write up.

other problem that you have with shunt trip (i had the same problem) but im jsut adding 5kw battery that i had from before in front of it (shunt trip breaker) with its own bms so if batrium trips the shunt sol-ark still has some battery and wont have a heart attack (extra battery is not mounted yet on the floor)

as im adding more 280ish amp packs im planning on adding the victron distributor thing with fuses for each 16x pack

(pardon the mess was moving stuff around lately and its temporary permanent work in progress)
This is an interesting setup. I am in the process of building the same setup Batrium with Sol-ark and that same Shunt Trip.

It will be great if you can share your experiences and how you made Batrium to Sol-Ark.
 

audreez

New Member
see below, i did a quick write up so someone else might find it if they need to

 

coolwaterxii

Solar Enthusiast
see below, i did a quick write up so someone else might find it if they need to

Thank you!
 

audreez

New Member
the only thing that might be bad is if that 5kw battery goes dry (if batrium trips the breaker), but im going to try and figure out a good low battery voltage minimum ion sol-ark so the bms should never disconnect, also theres a setting in sol-ark that says stop on bms error (not sure if that actually works with current hack, will try to test that this weekend
 
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