Enphase Zero Grid Export Help

[Grounding Rod]

Hello - Looking for some help with Zero Backfeed to grid device or method. I am using Enphase 7+ inverters and there will be times that my Solar array will be generating more power than I need. I do not want to have the excess solar power from entering the grid. Since Enphase does not have such a function within their inverters, (besides their expensive management devices) is there a device that can monitor the grid power and ensure no power enters the Grid? I’m stumped and any suggestions would be appreciated.

 

[timselectric]

You want to search for a dump load controller.

 

[Grounding Rod]

Thanks… The dump controllers I have looked at are related to batteries and seem to lack the intelligence to control backfeed. Is there a solution you have in mind? I am hoping someone has a simple solution that sits between the main power legs in the panel and senses when solar generation is above load and stops the backfeed through a dump or disabling the Enphase IQ7+ inverters. Unfortunately, Enphase won’t help as my array is not seen or managed by them.

 

[goldserve]

Do you have consumption CTs connected to the envoy controller? I saw some zero export profiles but I’m not sure how well they work.

 

[DIYrich]

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[Grounding Rod]

Thanks Goldserve.. I am not using envoy or IQ communication… but I read the same thing about the zero export profiles. My array in not connected to Enphaste through their management devices as stated above.

 

[goldserve]

Hrm, you are going to need something more intelligent or something to absorb the power because the MPPTs will just maximize the power production and if you have no grid connected, the voltage will just start ramping up on the output until the grid voltage is out of range (something you shouldn't do). If you have grid connected, it is hard to prevent power leaking out. You should have some battery charge controller connected and set a voltage operated relay on the battery side to start drawing power when the batteries are almost full. Turn off the dump load relay when battery falls below a certain voltage range. If you had something like a smart shunt, you can use some programming to communicate with the shunt and operate a relay based on SOC % which is more accurate than voltage of lifepo.

 

[Grounding Rod]

Thanks.. interesting. I’ll do some research on that and see what I can come up with. Seems like the need for a device/system for zero exporting is pretty common. I just can’t believe that there is not something out there using CTs that can’t do simple power measurements and then execute an if-then-else logic that is agnostic.

 

[DIYrich]

I just can’t believe that there is not something out there using CTs that can’t do simple power measurements and then execute an if-then-else logic that is agnostic.

If-then is a binary question for a non-binary problem. If-then is: if exporting, then stop production. Your problem is: producing X watts, with Y watts of excess. How do you deal with EXACTLY Y watts.

 

[Grounding Rod]

Thanks for helping me to further articulate the problem. That said, I assume you have some thoughts to resolve “Y”?

 

[goldserve]

Y watts varies instaneously and since you have no direct control of the microinverters unlike dc solar system connected to a hybrid inverter with battery as a dump of energy, it is going to be hard.

 

[DIYrich]

Thanks for helping me to further articulate the problem. That said, I assume you have some thoughts to resolve “Y”?

No solution. It is not "simple power management". Some inverters can use batteries to suck up the excess. The problem is when batteries are full. Sol-ark and eg4 18kpv can do it, but will turn off AC PV when batteries are full.

 

[zanydroid]

What is the end goal? Just to sus out whether its worth putting it together.

It's not as unpossible as building your own MPPT to electric car traction battery box (well this is still possible if you are an educated and experienced power electrical and electronics engineer, while you need quite a lot simpler theory and practical skills to get what you want), but it is not turnkey either.

You would have to do a fair amount of learning and possibly coding, to switch in dump loads or disconnect your solar array incrementally, to truly achieve zero export.

For instance, you can set up 50%, 25%, 12.5% increments of solar array on separate contactor controlled branches. Or dump loads in similar granularity. Just as is done in digital to analog converters. There's some discussion threads here on that, and on similar stuff like incrementally switching inverters to control export from battery with non throttlable inverters

At that point arguably you could have switched to a more zero export friendly vendor or architecture for the same amount of rewiring work.

 

[solar8484]

Getting an iQ Envoy and use a zero export profile is likely your cheapest option.

 

[zanydroid]

Yes it's not clear what requirement is driving the aversion to using the standard Enphase solution. For better or worse they have an ecosystem that covers this use case, and their implementation satisfies the requirements of both installers and grid operators.

I bet your research time alone is going to exceed the cost of the Enphase ecosystem solution, with a more fragile solution needing annoying ongoing maintenance, tuning, and design refinement (assuming no PLC signalling issues with the Enphase one).

 

[kennyb]

Getting an iQ Envoy and use a zero export profile is likely your cheapest option.

This. It's a few hundred dollars and 3 CTs.

I ran an IQ system "headless". For 4 years and finally added the envoy when I had 3 inverters "die". Added the envoy, reset the micros and updated the grid profile to a f/w profile. It's worth the money.

 

[Grounding Rod]

Thanks All.. Your feedback is awesome. I agree with the assessment to go with the IQ Envoy. It seems that there are several models of IQ Envoy / Gateway. I assume the “Envoy S” is the correct model to achieve zero exporting. Also, when I bought the 7+ inverters off eBay, they did not come with inverter identification numbers even though the vendor said they were new. When questioned, they said they had bought them from a third party. Will the Envoy ”See” these by connecting to them?

Background: I have two electric meters on my property. One services the barns and swimming pool which is my project to eliminate this cost in power. The power company will not do net metering nor do I want any unwanted communication with them. My design is attached currently without the Envoy. I have completed the build of a dual axis tracker that is being tested and working great. I have six REC 365W solar panels.

One again.. THANK YOU!

 

[goldserve]

Thanks All.. Your feedback is awesome. I agree with the assessment to go with the IQ Envoy. It seems that there are several models of IQ Envoy / Gateway. I assume the “Envoy S” is the correct model to achieve zero exporting. Also, when I bought the 7+ inverters off eBay, they did not come with inverter identification numbers even though the vendor said they were new. When questioned, they said they had bought them from a third party. Will the Envoy ”See” these by connecting to them?

Background: I have two electric meters on my property. One services the barns and swimming pool which is my project to eliminate this cost in power. The power company will not do net metering nor do I want any unwanted communication with them. My design is attached currently without the Envoy. I have completed the build of a dual axis tracker that is being tested and working great. I have six REC 365W solar panels.

One again.. THANK YOU!

Production from the pv should go through a CT connected to the envoy and it also supports another set of CT to measure consumption of the incoming service.

With regards to provisioning, you need to have access to the installer toolkit and the envoy will see the serial numbers of the iq7s that you got but may be associated with another system and envoy device if they are not new. I don’t see why someone had to peel the bar code off but you might find out when you contact tech support to re-provision the micros.

 

[Grounding Rod]

I just wanted to let those looking for an answer know that while there may be other solutions for this problem, the Enphase IQ Gateway is the way to go. While the unit cost around $600, its ease of setup and the information it captures in phenomenal. Most importantly, through its Live Stream feature, it graphically shows you how it satisfies the load of your home between the grid and PV system real time. From my perspective, it was well worth the money… and I can pinch a penny!

The hardest part was finding the correct profile. After good discussions with Enphase help desk the one to use is:

IEEE 1547:2018 Base Profile - No Export (1.3.1)

Thanks to all who helped get to this solution!