Neutral Ground Bonding for Semi-Offgrid System (Sol-Ark 15k)

[Solarkid]

Hello Everyone,

I am working on an off-grid system, i.e. non-grid tie, but with a sort of backup from main power in case my solar goes out. I was running through everything and I am running into a bit of a pickle. I have a Sol-ark 15k inverter which is designed to be installed with the 200 amp service pass-through, which allows the main service to be directly installed into the inverter and then feed it back out to the main panel. This is a cool feature so there is no need for a critical loads panel; however, that would require the need for contacting the utility and getting service shut off and permits and such. I am not going that route as I am not doing my solar panels the typical roof mounted way or the normal massive ground mount array and I do not think it would pass my city permitting. Anyways, I will effectively be running my Sol-Ark sort of off-grid.

I am going to install a critical loads panel/sub-panel and move a few circuits from the main panel over to the critical load panels to be powered by the inverter. However, I would like to be able to have a back-up in case my batteries run dry or something happens to my solar system. The Sol-ark has the pass through design so since I am not doing the 200 amp service route, I could have a 100 amp breaker from the main panel to the Sol-ark and then setup the sol-ark to not back feed the grid. My concern since I am not getting a permit, that if something goes wrong and for some reason it does back feed the grid, I could kill someone (worst case scenario) or potentially have the utility come knocking. My current thought is to do a 100 amp breaker from the main panel to the critical loads panel and then have a breaker lockout (Basically a Generator breaker lockout) installed to only allow either the breaker fed by the inverter or the breaker fed by the main panel to be ON at any one time. This would prevent any back feeding.

This leads me to the question of netural/ground bonding. The main panel has the neutral ground bond and currently the load panel I purchased also has a neutral ground bond. Since I am technically, off-grid during normal operation and the main panel breaker will be off. I am not sure how the neutral and grounds will work. For the circuits that I move from the main panel to the critical loads panel, can I leave the neutral and grounds in the main panel and only move the hot wires and breakers to the critical loads panel? That would leave only a single neutral ground bond; however, it would be two power sources sharing a neutral/ground bond, if that makes sense. I have modified the sol-ark wiring diagram to show what I am talking about.

If my current drawing does not work, I read something about using a 3-pole transfer switch that has 2 hots and a neutral switch but I have not been able to research that too much.

I am sorry if this made no sense haha. I had a hard time trying to type this up. Please let me know what you think!!

 

[jyoung1]

I will be wiring my system the same to avoid the power companies interconnection regulations. If I understand correctly, you only bond gnd and neutral in main panel, not sub panel. This should already be done in standard house wiring. The sub panel neutral and gnd come from the output of the inverter. Those neutral/gnd connections from inverter should be carried through inverter from the Main Panel's neutral/gnd connection. This is not always the case pending what inverter you use. This way the subpanel circuits have the neutral/gnd connection from the main panel. If this is not correct, feedback is appreciated.

 

[Mattb4]

My question (not familiar with this AIO unit) is, if it is designed to feed to the grid, does it do it from the AC in supply? If it does than you can not use it as you are attempting. Isolating the sub panel via a breaker lockout would work (a transfer switch would be better) but it does nothing to prevent back feeding.

There are off grid hybrid inverters that do not have the ability to feed back to the grid that would work in this application though.

 

[jyoung1]

Sol Ark can feedback from the grid connection. You can tell it not to or not wire the grid connection. You can use completely off grid application if you want.

 

[Mattb4]

I have no doubt that you can have it completely grid isolated if it is not plugged into the grid. The rest I guess I would have to research. But thanks for the information.

 

[jyoung1]

Based on my research, he should be ok wiring the gnd and neutrals from main panel to sub panel. Just don't bond the two in the sub panel.

 

[Nobodybusiness]

Put

Hello Everyone,

I am working on an off-grid system, i.e. non-grid tie, but with a sort of backup from main power in case my solar goes out. I was running through everything and I am running into a bit of a pickle. I have a Sol-ark 15k inverter which is designed to be installed with the 200 amp service pass-through, which allows the main service to be directly installed into the inverter and then feed it back out to the main panel. This is a cool feature so there is no need for a critical loads panel; however, that would require the need for contacting the utility and getting service shut off and permits and such. I am not going that route as I am not doing my solar panels the typical roof mounted way or the normal massive ground mount array and I do not think it would pass my city permitting. Anyways, I will effectively be running my Sol-Ark sort of off-grid.

I am going to install a critical loads panel/sub-panel and move a few circuits from the main panel over to the critical load panels to be powered by the inverter. However, I would like to be able to have a back-up in case my batteries run dry or something happens to my solar system. The Sol-ark has the pass through design so since I am not doing the 200 amp service route, I could have a 100 amp breaker from the main panel to the Sol-ark and then setup the sol-ark to not back feed the grid. My concern since I am not getting a permit, that if something goes wrong and for some reason it does back feed the grid, I could kill someone (worst case scenario) or potentially have the utility come knocking. My current thought is to do a 100 amp breaker from the main panel to the critical loads panel and then have a breaker lockout (Basically a Generator breaker lockout) installed to only allow either the breaker fed by the inverter or the breaker fed by the main panel to be ON at any one time. This would prevent any back feeding.

This leads me to the question of netural/ground bonding. The main panel has the neutral ground bond and currently the load panel I purchased also has a neutral ground bond. Since I am technically, off-grid during normal operation and the main panel breaker will be off. I am not sure how the neutral and grounds will work. For the circuits that I move from the main panel to the critical loads panel, can I leave the neutral and grounds in the main panel and only move the hot wires and breakers to the critical loads panel? That would leave only a single neutral ground bond; however, it would be two power sources sharing a neutral/ground bond, if that makes sense. I have modified the sol-ark wiring diagram to show what I am talking about.

If my current drawing does not work, I read something about using a 3-pole transfer switch that has 2 hots and a neutral switch but I have not been able to research that too much.

I am sorry if this made no sense haha. I had a hard time trying to type this up. Please let me know what you t

I put in a 200 amp transfer switch.
I have utilities on one side and Solark on the other.

When you have the solark connected to the main or critical loads panel the neutral and ground are bonded in the main panel.
It’s the same as when utilities are connected.

If you do not have the Grid input connected to the inverter then you can’t back feed or if you turn off Sell then you can’t back feed.

 

[jeremyee]

I am doing the same thing using Victron. I have the grid feeding the inverter AC in and the AC out feeds the breaker panel. In the ecent the battery's run low it converts pash-through mode and back when battery's are charged. Make sure the inverter when in pass-through or inverter mode does NOT bond the neutral and ground in the inverter. the bonding should be only in a single location and at the first point of disconnect.

Below is the setup I am going with just in case I need to work on the inverter while also allowing for a disconnect outside for the power company or fire dept.