Some zero export inverter questions

[zanydroid]

Did you look at all of the compliance questions? Most of my stuff is out in a solar shed and most likely not in compliance with those codes.

I read it and it's verbiage I've seen before and agreed to/complied with. Granted, on some very vanilla hardware that everybody else has.

Can you quote the specific sections that you are concerned with?

If I want to purchase an "approved" inverter, I might as well just pay them to do an install.

Overblown. As a strawman you can buy a $400 grid tie 2000W inverter, that is compliant with first three bullets (1741, 1547, automatically disconnect). If you payed someone you will get a +100% overhead.

 

[1201]

Did you look at all of the compliance questions? Most of my stuff is out in a solar shed and most likely not in compliance with those codes. The automatic cutoff switches they want don't exist and would not be easy to implement. My meter is on a pole 40 feet away from everything. If I want to purchase an "approved" inverter, I might as well just pay them to do an install. So no, not going to happen.

As I said earlier, I started this project nearly 20 years ago so it is a mix of 3 different systems. It's been working fine all that time. And as I said, up until they installed the smart meters and started hawking their own systems, nobody cared what you did. The cost to do things they way they want is just not worth it.




My breaker box in the house is not in a good location to easily to branch off separate circuits.

I'm curious, what grid tie inverters are you currently running?

 

[Texas-Mark]

When they called me and I talked to them I was told the

I'm curious, what grid tie inverters are you currently running?

I'm not now. I was running a cheap made in China one when it back-fed that one day.

When I talked to them after they called, they said the inverter "disconnect" had to be at the meter. My meter box has some breakers (for my sheds) and one 200A one that then goes to the house panel. They told me those breakers were not good enough to use as disconnects, and I needed a separate "dedicated" one for the inverter. To do it the way they want, I would have to trench again to the pole.

 

[zanydroid]

When I talked to them after they called, they said the inverter "disconnect" had to be at the meter. My meter box has some breakers (for my sheds) and one 200A one that then goes to the house panel. They told me those breakers were not good enough to use as disconnects, and I needed a separate "dedicated" one for the inverter. To do it the way they want, I would have to trench again to the pole.

Ah ok, this annoying rule. I'm not subject to it, and it sounds like a stupid rule. I believe some places want this rule because they (for unknown reasons) want the house to still have power when the inverters are turned off.

EDIT: For the second iteration on my system, the plans drafter wanted to add an exterior disconnect for the new inverters. Naturally, I did not want to pull extra 80 ft of wire and pay for an outdoor rated disconnect, so I told them to take it off since it is not required locally.

Would they be willing to accept remotely open-able breakers that trigger if a master breaker or switch at the meter is opened? There are UL-listed breakers capable of doing this. If this is OK then you can use network or low voltage cable to signal this. Low voltage would require you to dig a smaller trench.

Here they (city and PG&E) allowed me to use the disconnect for my whole house as the disconnect. Because all grid tie (interactive) inverters under it will automatically turn off when that one is disconnected.

A lot of places allow you to have K throws to disconnect all inverters, provided all throws are in the same panel. Same idea as the "6 throws" rule for disconnecting power to a house.

 

[1201]

When they called me and I talked to them I was told the


I'm not now. I was running a cheap made in China one when it back-fed that one day.

When I talked to them after they called, they said the inverter "disconnect" had to be at the meter. My meter box has some breakers (for my sheds) and one 200A one that then goes to the house panel. They told me those breakers were not good enough to use as disconnects, and I needed a separate "dedicated" one for the inverter. To do it the way they want, I would have to trench again to the pole.

Correct. That's a standard rule afaik. That sucks and the trenching. I had to trench 80ft manual and it was not fun.

You have to choose the path of least resistance for you.
1. Submit the plans and hope they approve without inspecting. Worst case they inspect and deny.

2 . Do a good zero export inverter with minimal backfeed and hope they don't notice it or say anything about it

3. Do a system that can feed your whole house. Generator interlock to main panel, so you are either feeding the house from inverter or from the grid but not both at the same time. If you manage loads you might even be able to get by with a smaller inverter.

4. Just forget about solar. You only pay .09/kwh

 

[Texas-Mark]

4. Just forget about solar. You only pay .09/kwh

That is why I do this as just a hobby, but also want to stay off the radar.

 

[1201]

That is why I do this as just a hobby, but also want to stay off the radar.

Best of luck with that. Be sure to let us know the outcome

 

[wheisenburg]

What you are describing here is a capability that hybrid inverters call Peak Shaving. The Schneider XW pro has this ability, but it only works well if you also go with their charge controller which basically send the PV to the battery of invert it immediately for current consumption. The XW Pro has an output of 6800 watts. This is for continuous use. For surges it can supply up to 12,000 watts for up to a minute. I have a dual system with three 100 amp batteries. It will trip the batteries before it quits.

Basically, the inverter will blend the power between the grid, the batteries and the current PV input to keep usage at a target import wattage / amps.

Any AC coupled grid tied system is going to have problems reacting quickly enough. If you are actually grid tied the hybrid inverter can't use frequency shifting to adjust consumption. to really insure that your consumption

 

[Texas-Mark]

The biggest issue I have is that my "idle" consumption can be as low as 300 watts. So for example when the HVAC turns off, I would need to ensure that whatever inverter I am using can throttle back fast enough. From the posts here, it seems that can be an issue with any non-export inverter.

For now, I am putting this project on the back burner. I just replaced my AC condenser unit with one that is 20% more efficient. Given the low cost of electricity here, I don't see an immediate need move forward.

 

[12kw_2021]

Stay away from microinverter if you are afraid of exporting to grid. They can't react fast enough.

Just wanted to comment, that if you install a "zero export grid profile" on enphase microinverters that grid profile worked very well for me for 3 months to allow me to operate my 12Kw PV system prior to the local supplier sign off. See image below... I was experimenting with trying to use the Sol-ark only for zero grid export for my AC coupled PV, and that is why you see some export in November, which stopped in December, when I made the change to the Enphase micro inverters.

I added 2023 table as well, my system was approved in March, and I removed the zero export grid profile so you see normal grid export from April on.


Just trying to clarify, not intending to start a fight.

 

[Hedges]

How about connecting an AC coupled battery inverter for zero export peak shaving, with PTO.
Just put it near wherever the disconnect is required to be.

That gives you plausible deniability for spurious export.