I can say that it makes sense for that to be done. But I cannot say whether it makes sense for you to be the one doing it, and I cannot see what your setup actually looks like.
And it does not cover what has to be done with the grounding. The neutral bar in the disconnect should not be grounded to the box, but there is more to it than just that.
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My plan and thanks
Thank you so much for your reply. This is so helpful as I want to do this wiring tomorrow. I will run neutral wire from inverter to ac disconnect but I will not setup the ac disconnect switch to disconnect the neutral. I will just put a neutral bar in the ac disconnect and connect the neutral wire from the inverter to it and then I will run a second neutral wire connected to the same neutral bar in ac disconnect and run it to the neutral bar in the electric service panel. Could you let me know if this makes sense? thx!Leave a comment:
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Since you are in the US, there will be a neutral wire at your service entrance whether it is 240/120 split-phase or something else.
The UL approval for the inverter requires that it test that the two sides of the 240 service are approximately equal in voltage to neutral before starting up, so you will have to connect the neutral.
The rule that then comes into play is that the neutral has to follow the same path as the two hot wires. Although you must not actually set up the switch to disconnect it.Leave a comment:
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neutral wire or not
I looked in manual for the sunny boy 3800u inverter that I have and it states:
Utility Configuration Jumpers
The SB3800U comes from the factory pre-configured for utility interconnection with
neutral. The SB3800U may be reconfigured for grids without neutral by setting the
jumpers on the board of the SB3800U.
The utility configuration jumpers allow the SB3800U to be connected to transformers
where the neutral is not present, such as the 208V and 240V Delta, shown in Figure 4-
3. Refer to the figure below for a description of jumper settings.
There is a connection on the inverter for a neutral wire but I am not sure if I should use it to connect the inverter to the ac disconnect and then to the panel. From reading the manual it states that the sunnyboy may be reconfigured for grids without neutral. I am not sure if my grid has a neutral or not. Should I look at the service lines coming into my panel to see if there is a neutral wire coming in? I am not very familiar with this. Any help would be appreciated. thx!Leave a comment:
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If the inverter output is 240 volt and the inverter manufacturer's instructions do not direct you to connect a neutral, then you do not need to run one. But you must have an grounding conductor (EGC) unless the conduit meets that requirement.
What you cannot do is run a required neutral the short way instead of running it out to a disconnect and back.Leave a comment:
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question about neutral wire
I based my design upon another design I saw of an array that a friend had installed. Anyway, if you look at the design I uploaded, there is no neutral wire running from inverter to AC disconnect and no neutral wire from AC disconnect to the panel. Should I have be running a neutral wire from AC output on inverter to AC disconnect and then neutral wire from AC disconnect to service panel? Please advise. thx!Leave a comment:
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If you are connecting your inverter output to a backfed breaker in your inside panel, that will be the overcurrent device for the circuit. The current that the inverter itself produces is already limited by the size of the panels and so does not need protection from that end. The AC disconnect outside will serve the purpose of keeping the POCO happy and does not need fuse or breaker located there.Leave a comment:
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One more question, my ac disconnect needs to go outdoors per utility company. I bought one that is rated for outdoors but it is not fusible. In other words, I cannot add fuses to it. Is that ok, or do I need an ac disconnect which I can add fuses to to connect my inverter to the electric service panel?Leave a comment:
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You can always have two inverters. So if you have a string of 8 now and one inverter, to expand, just "do it again" and have a second inverter/string wired into another backfeed breaker. Since you bought the inverter used - do you know the # of years it was in-use? They don't last more than maybe 12 years.
The way we have my PV setup now (going live anyday now) it is two Power One Aurura 3.6 inverters - tied together into one small subpanel, then the 240V single-phase goes to the house with a supply-side connection so that there is no backfeeding at all in the house.
Going from the electric dryer to the nat gas dryer is one move in the right direction for planning Solar PV. You want to conserve the electric usage and this is one good way to do it. Should save dozens of kWh per month moving to natgas. And for free too!Leave a comment:
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Ok, if dryer is on the current 30 amp breaker, I will remove it to free up two breaker slots and put a 20 amp breaker there per your recommendation. If and when I upgrade my inverter to a higher capacity I will then pursue the panel upgrade option. Extremely appreciative of all your help.
thanks!Leave a comment:
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A 40A breaker feeding a 100A panel will not fly A 20A will The #8 and 40A breaker are fine but it will mean a panel upgrade. (Which you should probably do anyway.Leave a comment:
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Ok, got you. I was kind of thinking for the future of having the bigger breaker if I do a 2nd or 3rd string with 12 more panels in the future and maybe doing a bigger inverter to take advantage of the extra output. However, I didn't realize your point about not oversizing the breaker for the current application as the inverter will only put out 16 amps. It sounds like a 40 amp breaker on this would be ok with 8 gauge wire but due to NEC code it would be much higher than the 16 amps the system is putting out. So, it sounds like I should do the 20 amp breaker now (I am assuming 8 gauge wire won't hurt and can only help and I will have extra lying around) and then in future if I upgrade inverter to a sunnyboy maybe 4000 or higher that I at that point upgrade the breaker to a higher amperage, but not before.
Let me know if my logic makes any sense and as always much appreciated
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