Mike 134
Solar Enthusiast
You have no idea what you are doing and yes a "grid tied" inverter can kill a lineman when installed by an uneducated DIYer. 38 year member of IBEW
On grid without utility consent.
- Thread starter Electroaliance
- Start date
I think we're having issues with terminology again.
"Gried Tied" typically means bidirectional (so the inverter can export). An inverter that doesn't support bidirectional power that has AC input is not "grid tied" even though it has a grid input connection. That kind of inverter is simply "grid connected" at most (or whatever else you want to call it).
Simplest way to be certain you can't send power back to the grid at all is to buy an "off grid" inverter. They may have an AC "grid" in, but it isn't going to push power backwards.
"Gried Tied" typically means bidirectional (so the inverter can export). An inverter that doesn't support bidirectional power that has AC input is not "grid tied" even though it has a grid input connection. That kind of inverter is simply "grid connected" at most (or whatever else you want to call it).
Simplest way to be certain you can't send power back to the grid at all is to buy an "off grid" inverter. They may have an AC "grid" in, but it isn't going to push power backwards.
Yep. A grid tied inverter is specifically designed to not pose a risk to linemen. And it's impossible for an amateur to alter it so it DOES pose a risk.
If, on the other hand, an amateur decides to connect the output of their off grid inverter to the grid, they could pose a danger to linemen. This effectively never happens, because if the amateur tries this while the grid is up, it will blow out the inverter almost instantly.
So in real world cases there's virtually no risk to linemen.
Now, there are pathological cases you could construct (if you know what you're doing) that will attempt to backfeed the grid via a hybrid inverter. But now we're into deliberate sabotage, not a clueless but well meaning newbie doing it accidentally.
At a higher level, though, an amateur who doesn't know what they are doing are indeed posing a risk, but to themselves and the people around them. 240VAC power is fairly dangerous, and 400VDC is far more dangerous. No one without basic electrical training/experience should be messing around with those voltages, and asking questions on the Internet is not an adequate way to get that training. Fortunately there are plenty of experienced people around in the real world who are willing to lend their expertise to help newbies do what they want to do (relatively) safely. I'd encourage any non-electrical person who wants to experiment to find someone like this; it's far faster (and far safer) to talk to someone who can see what you're doing than to try to ask questions on the Internet.
Bluedog225
Texas
- Joined
- Nov 18, 2019
- Messages
- 3,137
Connecting to the grid requires inspection to ensure safety. Not your call. Not open to debate. Full stop.
MajicDiver
Solar Enthusiast
Absolutely, our meter counts power both ways as consumed power. This is something that probably varies based on meter age and what type of “default” meter a particular distributor installs.
Bluedog225
Texas
- Joined
- Nov 18, 2019
- Messages
- 3,137
Read the thread title.
MajicDiver
Solar Enthusiast
I am fully retired after working a career as a engineer at a large utility. I am highly confident in stating that the actions ( or lack of action) of the utility or distributor a lineman is working or contracting for are a far larger major injury or death risk than any DIY grid tie system. Also, the risk of a car hitting a bucket truck in use is significant. Likewise, someone stupidly hooking up a generator while still grid connected after a storm with grid down can be a risk.
Tulex
Solar Wizard
Too many things getting crossed up from the original question.
There are many variables that make it impossible to answer definitively.
What type of meter, what type of inverter, what type of neighbors.
I have an analog meter. It spins backwards when I export. As long as my meter reading is higher each month, they can't tell. At some point they may question why my usage has dropped.
Many people have smart meters that report the smallest export, there is a thread on here about the power company calling them out on the smallest amount. There are digital meters that aren't smart meters.
My understanding is that there isn't a AIO inverter that is perfect when it comes to the zero export setting. My Sol-Ark 15K isn't, that I know.
About killing linemen, that isn't part of this discussion. There are lots of ways to do that that don't involve a grid tied inverter.
So, Sparky basically answered your question, as for grid tied with zero export programmed, it's not perfect.
There are many variables that make it impossible to answer definitively.
What type of meter, what type of inverter, what type of neighbors.
I have an analog meter. It spins backwards when I export. As long as my meter reading is higher each month, they can't tell. At some point they may question why my usage has dropped.
Many people have smart meters that report the smallest export, there is a thread on here about the power company calling them out on the smallest amount. There are digital meters that aren't smart meters.
My understanding is that there isn't a AIO inverter that is perfect when it comes to the zero export setting. My Sol-Ark 15K isn't, that I know.
About killing linemen, that isn't part of this discussion. There are lots of ways to do that that don't involve a grid tied inverter.
So, Sparky basically answered your question, as for grid tied with zero export programmed, it's not perfect.
42OhmsPA
What's in a title?
Technically.
Technically, so does simply adding one outlet to an existing branch circuit, in some jurisdictions. (I really wonder how many people do that.)
But neither of those require power company involvement (assuming using an off grid inverter).
If you want to try to make it a little more gray, put a plug on the inverter AC in. Now it is "temporary"
Retired Duke Energy EE.
I can confirm it.
I exported a little to the grid to test this and was charged for the export the same as if I had imported it
OzSolar
Whatever you did, that's what you planned.
I know several lineman. They are trained to "work it hot or ground it dead".
They've shared stories while working to restore power during storm recovery. If they even remotely suspect a generator or solar system is operating without proper isolation from them they switch from work it hot mode to ground it dead mode which usually results in damaging the generator. They might even let out a bit of a sadistic laugh while they are telling the story.
They've shared stories while working to restore power during storm recovery. If they even remotely suspect a generator or solar system is operating without proper isolation from them they switch from work it hot mode to ground it dead mode which usually results in damaging the generator. They might even let out a bit of a sadistic laugh while they are telling the story.
yup, and they are well aware that a signed utility approval paper does not act like a wireless back-feed isolation device as some seem to think.
Trying to have a small simple zero export grid tie system to reduce your grid usage often is just a waste of money. They sell a lot of cheap grid tie micro inverters that plug into your present electrical system but are prone to failure. Almost none of them can prevent unintended export which brings you to the attention of your utility company if your meter is capable of detecting it.
Better off to plan and install a properly set up GAB (grid as backup) type AIO. This will reduce your grid consumption and also be a source of power if the grid is down. Be aware that some hybrid AIO's can export if setup to do so.
Better off to plan and install a properly set up GAB (grid as backup) type AIO. This will reduce your grid consumption and also be a source of power if the grid is down. Be aware that some hybrid AIO's can export if setup to do so.
Kenny_
Solar Addict
This!
I am curious on how to have a system completely islanded from the grid as well. My utility has a smart meter on my house and I do not want to see what kind mess I would have to deal with if they detect a single watt of power back flowing onto the grid. I heard that could be not fun. It seems like several of those all in one hybrid systems can stop backflow, but I would prefer a clean break where the grid can't touch any solar power
what would happen if you did this? I have seen those solar products on places like amazon that look like it has an extension cord that you just plug in a regular wall outlet and it is somehow supposed to just be like a grid tied solar system. I do not trust any of them at all, of course.
Like this one: https://pluggedsolar.com/
I find this very sketchy.
GXMnow
Solar Wizard
- Joined
- Jul 17, 2020
- Messages
- 2,749
A proper "Grid Tied" inverter can safely be plugged into an outlet and work just fine.
The way they work allows them to sync with the grid before they produce any power output. The plug with pins won't be putting out any power until it is plugged in and sees a good grid first. Once good power is going into the box, it syncs it's internal sine wave and produces an output current in step with the existing sine wave. I have 16 microinverters on my roof that are doing this right now. They are hard wired, but they work the same way. This is very different from an engine driven generator or off grid inverter that produces it's own voltage waveform.
Here is a simple rule "If the inverter puts out power without a grid connection, DON'T connect it to the grid!"
