tigo

[Ai4px]

My solar system complies with nec2014 rules which states that the string gets disconnected on the roof and not all the panels individually. I'm about to add more strings and was looking for a SMA remote shutdown box but they (obviously) are discontinued. I was thinking I could get one TIGO module per string to satisfy the requirement. I see the Tigo modules are rated for 80v but that's on the panel side of the device. Surely they can withstand a 600v string on the string side of the device?

 

[400bird]

They are designed to install with one under each 80 VDC max panel. So, no I don't think they'd survive at 600 volts.

 

[Ai4px]

They are designed to install with one under each 80 VDC max panel. So, no I don't think they'd survive at 600 volts.

for the sake of discussion... It's unlikely that all the modules would shut down at exactly the same moment (like down to the mS level.... so surely individual Tigo modules would have to withstand the entire string.... They have a rating of 1000Viec. . But you could be right!

 

[Ai4px]

i just read the FAQ for the TIGO modules.... Reading between the lines.... a single unit can do it but it won't be NEC 2017 compliant because that requires all panels to be disconnected from each other.

Can a single TS4-S or TS4-F unit disconnect an entire string?

For full NEC compliance, all modules in a structure-mounted system are required to have RSD functionality.

The Rapid Shut Down (RSD) feature of TS4-S and TS4-F functions on the module level. This means the controls for RSD are specific only to the PV Module that the unit is attached to. All other Modules on the string would still be active (not RSD compliant).

 

[400bird]

Interesting, I haven't tested it, but my assumption was it opened the panel side and shorted the sting side straight through. Maybe it would work for your plan.

 

[Ai4px]

Interesting, I haven't tested it, but my assumption was it opened the panel side and shorted the sting side straight through. Maybe it would work for your plan.

Oh dear!! Ground bonds are not current carrying conductors, so the only way they could drain capacitors would be to shunt the PV+ and PV- together...... so that is one possible mode.... PV isolated and the string side shorted showing 0.6v..... Maybe someone in possession of one can tell me more.... doggone it!!!

 

[400bird]

There's no ground connection on my Tigo RSD modules.
I do not believe Tigo is responsible for draining any capacitors, the inverter is responsible for that.

However, I can't really do any test to verify this. My RSD modules are the 2F (one module disconnects 2 panels) version. And only under a 2S2P portion of my system. So, unless you have any testing ideas, I don't have any way to prove or disprove any theory of operation for what I have here.

 

[Ai4px]

There's no ground connection on my Tigo RSD modules.
I do not believe Tigo is responsible for draining any capacitors, the inverter is responsible for that.

However, I can't really do any test to verify this. My RSD modules are the 2F (one module disconnects 2 panels) version. And only under a 2S2P portion of my system. So, unless you have any testing ideas, I don't have any way to prove or disprove any theory of operation for what I have here.

TLDR: I think it'm answering my own question.... the .6v voltage per module I think says that the string side shorts out as a forward biased PN junction .... 0.6v is the standard voltage drop of a diode when it is forward biased. I think one togo module simply shunts out the panel(s) it's attached to. that leaves the other panels to eventually shut off..... so you cannot use one Tigo to kill a whole string....

Thanks for letting me think thru this.....

 

[400bird]

0.6v is the standard voltage drop of a diode when it is forward biased.

It's so obvious now that you say it! I never considered what was going on inside the thing

Thanks for letting me think thru this.....

I learned a thing too!

 

[zanydroid]

Another thing about MLPE is that they draw power from the solar panels they are attached to so they have to have input on DC side.

Would the shunting idea also result in usable voltage when shut down? This is required for dark start. And there is a minimum number of panels you need in series to get enough voltage to bootstrap the transmitter.

But why do you need this? I thought there were other 2014 compatible array level shutdown approaches. Though the techniques must be rusty/not invested in since it’s an obsolete iteration of code.

 

[Ai4px]

Another thing about MLPE is that they draw power from the solar panels they are attached to so they have to have input on DC side.

Would the shunting idea also result in usable voltage when shut down? This is required for dark start. And there is a minimum number of panels you need in series to get enough voltage to bootstrap the transmitter.

But why do you need this? I thought there were other 2014 compatible array level shutdown approaches. Though the techniques must be rusty/not invested in since it’s an obsolete iteration of code.

Everything is obsoleted. The best I could do was bidding on an SMA rsd box like the one on my roof already. That’s a pig in a poke.