Delta H6 6000W Grid-Tied Inverter NEW Battery-less Backup UL1741 Rule 21 2MPPT

[Electrovet]

As far as the Grid Reconnect times: I would not recommend altering those settings in my opinion. In the event that you have an outage within your island, any inductive appliances will need a stabilization time of several minutes to prevent hard starting which could damage some appliances. I believe that could be the safety reason for the longer reconnect (I would set over 180 Sec). If you are fully powered and reconnecting, there should be no issue as synchronization should be able to be achieved in a few cycles. However another consideration is utility fault sensors in the event of a utility line fault such as a short caused by wind, transformer fail, car accident, or a downed line, will sense and reset three times before locking off. A short reconnect time may cause power bounces/surges on a faulting Automatic Utility Shutdown which may also damage sensitive property.

 

[MaMikee]

Inductive appliances need stabilization time? Not on the earth I inhabit. A/C & freezers, etc like to have a rest (let the oil settle) before restarting but series wound motors, etc don't even have to stop before being reconnected.

 

[Ampster]

The algorithms in UL 1741SA and CA Rule 21 are to protect the grid and not to protect any user equipment behind the meter. They are to keep all the GT inverters from disconnecting at the same time if there is some frequency event on the the grid.

 

[Hedges]

The algorithms in UL 1741SA and CA Rule 21 are to protect the grid and not to protect any user equipment behind the meter. They are to keep all the GT inverters from disconnecting at the same time if there is some frequency event on the the grid.

I read them as requiring the inverters to wait 299 seconds, then all disconnect in unison before 300 seconds if still outside frequency spec.

They would of course differ in exactly what frequency they recognized as out of spec and therefore have a time shift, whereas original UL 1741 if just at the threshold some would have immediately dropped off and others wouldn't.

The 5 minute delay gives the grid time to stabilize.
What I think is more interesting is if inverters implement frequency/watts or volts/watts and adjust their output. But frequency would be grid-wide, and some ends of the grid could want more power while others wanted less. Only voltage could signal inverters in different locations differently.

 

[Ampster]

then all disconnect in unison

That would require some complicated communication to get thousands of inverters to do that in unison. It would also defeat the purpose of Rule 21 which is not to shock the grid by doing that in unison. Inverters built to the new specs modulate down in response to frequency reductions.
I am not familiar with Rule 21 voltage specs. Voltage already varies at different parts of the grid every day.

 

[Hedges]

Not required to be in unison, just that if frequency goes out of spec (above 60.5 Hz), to the extent all inverters observe that at the same time, all will drop off 5 minutes later at the same time.

Modulate down in response to frequency increase is an optional implementation, not required.
"A Frequency-Watt function, which reduces real power on over frequency, is also allowed to be used given agreement by the utility."

For an inverter which doesn't implement Frequency-Watt, w0ce frequency exceeds 60.5 Hz, instead of being required to drop off immediately, under Rule 21 the inverter is required remain online a additional 299 seconds and is required to drop off by 300 seconds. If frequency exceeds 62 Hz it is required to drop off immediately.

So this gives grid 5 minutes to get frequency back under control before power from PV goes offline.

To the extent installed systems do implement Frequency-Watt, by raising frequency the grid will reduce the delivered power. But unless generators under other control mechanisms are told to reduce power and frequency is returned to under 60.5 Hz, at 5 minutes all the non-Frequency-Watt inverters will drop off. So it depends on having enough conventionally controlled generators to make up for 100% of the PV that suddenly goes offline (or storage to tied it over for 5 minutes until they return.)

How California’s Rule 21 inverter requirements expand grid capacity, limit energy (revenue) generation

A multi-year effort has been ongoing in California to update technical requirements for connecting Distributed Energy Resources (DER) to the grid, known as Rule 21. The experience of Germany was cited as one reason to take action. In Germany, significant grid destabilization problems arose when...

solarbuildermag.com

Frequency of course is the same grid-wide. That's apparently Western grid, separate from Eastern grid, separate from Texas grid.

Similar optional Volt-Watt function.
Above 110% of of nominal voltage, required to remain online for 20 seconds, above 120% required to disconnect. Unless it implements Volt-Watt.
That seems better for grid stability because any local area of the grid with too much generation compared to loads and transmission lines able to carry power away would result in voltage increasing so PV production would be reduced and it could achieve balance.
But only if a substantial fraction implement Volt-Watt, otherwise after 20 seconds too much goes offline.

Just my utility connection and branch to inverter shows significant voltage swing with PV production. Apparently the utility is likely to feed somewhat high voltage into long branches of wiring, keep voltage closer to upper limit under low load so it doesn't go below lower limit when everybody turns on their A/C or heat. This could cause a large PV system to push it a bit higher and disconnect. Changing inverter voltage settings outside spec isn't allowed. Using a buck-boost transformer would be a software-free way to accomplish exactly the same thing. Volt-Watt would have inverter adjust power output to keep the voltage within limits.

 

[Ampster]

That article does a good job of explaining how Rule 21 was designed to prevent the kind of system shock which they experienced in Germany. The article also explains the ride through required response which in my opinion would reduce the likeliehood that all Rule 21 inverters would drop off at the same time.

The only time that simultaneous drop off theorectically might happen would be on a significant over voltage event above 120% (288 volts). My old Xantrex inverter which was not Rule 21 compliant did drop out at something like 260 volts if I remember correctly. The solution was to call SCE and they explained that they would adjust the voltage at a nearby substation. That is an example of how there are always significant voltage differences within a grid.

That is why I do not think it is likely that a drop out of all inverters will occur. I do agree that it is possible.
The typical way the grid first shows a problem is what happened last summer in California. In that example demand exceeded capacity and the grid presumably expressed that with lower overall frequency and voltage. Of course that ocurred in the late afternoon so some inverters were already at reduced production. Those that remained on, presumably responded with ride through which limited shock to the system.

 

[Ampster]

That article does a good job of explaining how Rule 21 was designed to prevent the kind of system shock which they experienced in Germany. They also also explain the ride through required response which in my opinion would reduce the likeliehood that all Rule 21 inverters would drop off at the same time. The only time that theorectically might happen would be on a significant over voltage event above 120% (288 volts). My old Xantrex inverter which was not Rule 21 compliant did drop out at something like 260 volts if I remember correctly. The solution was to call SCE and they explained that they would adjust the voltage at a nearby substation. That is an example of how there are always significant voltage differences within a grid. That is why I do not think it is likely that a drop out of all inverters will occur. I do agree that it is possible.
The typical way the grid first shows a problem is what happened last summer in California. In that example demand exceeded capacity and the grid presumably expressed that with lower overall frequency and voltage. Of course that ocurred in the late afternoon so some inverter were already at reduced production. Those that remained on presumably responded with ride through which limited shock to the system. That gave CAISO time to order rolling blackouts so the remaining portions of the grid could return to normal. I did not hear any reports of inverters dropping out simultaneously or in unison.

 

[Hedges]

Reduced voltage reduces power draw by incandescent bulbs and resistance heaters, also universal motors. It increases current draw but not power draw of induction motors.
Reduced frequency reduces power draw of induction motors.

Most installed PV capacity would not have Rule 21 at this time, so below minimum frequency would knock all those off immediately. Below minimum voltage would knock off those which saw lowest voltage.

Having A/C thermostats and other loads respond to frequency and voltage would provide a great deal of leverage in preventing grid collapse.
Pagers integrated in them would work too.
I'd much rather have my A/C thermostat bumped up 10 or 20 degrees (for people without health issues) than have my refrigerators shut off for days.

If inverters didn't drop out (almost) simultaneously, that means frequency didn't go outside the range 59.4 Hz to 60.5 Hz. Beyond that they are required to drop off within seconds (if using original UL 1741). I've watched my Sunny Boys respond to frequency shift from Sunny Island, depending on the mode they are in.

 

[Ampster]

Most installed PV capacity would not have Rule 21 at this time, so below minimum frequency would knock all those off immediately.

No doubt that would happen to old equipment. I am not sure why that is relevant since the topic of this thread is Rule 21. At the rapid pace of deployment of solar in California I suspect there is a significant amount of Rule 21 equipment out there now anyhow so we may be splitting hairs. Just one anectdotal example is my ten year old Xantrex inverter which stopped working and was replaced with a Rule 21 Solaredge several years ago. I am still not convinced it is more than a theorectical risk. It has been an interesting discussion which has helped me understand Rule 21 better.

 

[Electrovet]

Inductive appliances need stabilization time? Not on the earth I inhabit. A/C & freezers, etc like to have a rest (let the oil settle) before restarting but series wound motors, etc don't even have to stop before being reconnected. You seem phobophobic to me.

Yes, correct that is what I had in mind, but obviously failed to convey precisely. I also was considering this would include motors under load with a modulating loads like air compressors, so I left it as an inductive appliance. But as a discounted phobophobe, I will gracefully bow out of yet another online blog of experts. These were something to consider, not emphatic statements, and my only fears in this regard are those of my senility in the field which I suffer. I only have one post, and though I thought some real world experience might help other DIY'rs not damage their homes, but obviously I am speaking into things I clearly cannot understand. I will remove my account, this was a mistake, thank you keeping this site clean.

 

[Hedges]

But as a discounted phobophobe, I will gracefully bow out of yet another online blog of experts. ... I will remove my account, this was a mistake, thank you keeping this site clean.

First of all MaMikee is a new member. Allow us less new members to take him into a back alley and beat him up for you.
Second, note that he didn't accuse you of being afraid of light, but rather afraid of phobias. Giving into a fear by bowing out of the forum might really mess you up if you are in fact a phobophobe. Please hang around a while longer.

Others have similarly felt they at first suffered abuse and encouraged newcomers not be be discouraged. But some did so inadvertently using an incorrect term, which I gently pointed out (my particular way of giving people a hard time.)

So welcome!

 

[Electrovet]

I understand. Thank you for the assurances and encouragement. But as I am getting older and less technical than the younger vibrant bloggers, I guess I am too sensitive to abuse from newbees and/or vets, and I just seek to have dignified communication. Unfortunately, most blogs I have watched eventually get to name calling for whatever reason, maybe it is too easy to say anything you want. I sense you have a clear level head. I was in ER yesterday, I am cleaning up my life for the end. Please remove my account or if you want, It can remain dormant. Thank you for your time. This is a really great resource that needs to continue. I found out great information. Thanks for accepting me. Dave

 

[Supervstech]

@MaMikee, calling out or catagorizing a member is prohibited... your comments have been removed.

 

[beesley]

I am thinking of getting one h6 myself and use it off grid batteryless mode to power a 9000btu or 12000btu split ac system let's say from 10 am to 4 PM with our Florida sun. It should be between 700w to 1100w load, which is very little compared to 6000w batteryless capability. I have 4.5 kw sunpower 305s panels available. The ac doesn't have inrush current . It has an inverter compressor. This should supplement my main ac. My idea is to use the solar power when is produced, instead of storing it for now. This is the beginning of my project. Most likely i will get some lifepo4 280ah from Xuba,and use a secondary inverter later. Any thoughts either positive or negative are very welcomed and appreciated.

Hi @Eri, did you end up trying this? I'm very interested in your experience because I want to do the same thing. Were you able to run your air conditioning system from the H6 without batteries? Any learnings from the experience you could share with me? Did any equipment get damaged? Thanks very much for your reply!

 

[Eri]

Hi @Eri, did you end up trying this? I'm very interested in your experience because I want to do the same thing. Were you able to run your air conditioning system from the H6 without batteries? Any learnings from the experience you could share with me? Did any equipment get damaged? Thanks very much for your reply!

Unfortunately i never did the project. More i thought about it, more it was financially irresponsible to use a whole array of 4.5 kw for only a 5 kwh per day of total output/usage on air conditioning( 5 hr of strong sun/day).That would have been theoretically a 20$ savings on monthly power bill at 12 cents per kwh. I would get the same savings by using only 4 panels out of 15 that i have, for direct dc water heater supplement (lower heating element set at 40 degrees higher than the upper one connected regularly on grid for heat when it drops below 125). Either using a 80$ water heater element 48v and 700w with built in dc thermostat from Missouriwindandpower,or using my existing heating lower heating element with a solid state relay or dc thermostat added. A lot more simple to achieve the same savings. I read that h6 will not restart automatically, and shutdown for the day after 2 or 3 times that it doesn't get enough solar while powering ac or any appliance during a cloud passing. Now you have to manually turn off and on the ac side. This will not be a self running system. Every morning you have to start your ac AFTER there is enough solar available, but you won't know how much power you have available ,until you put a load on the inverter. There is a very handy guy that did this on YouTube, and i believe he is a member here also.

Honestly take my advice and move on with a battery and inverter. Even a small battery like 500 wh or 1kwh will be enough buffer to have in case of a cloud . Maybe a solar generator with some panels will achieve the same as this troublesome setup. Definitely it will work, but not financially feasible. Think of the power curve of solar panels from dawn to dusk. You will use a very limited amount of power, compared to the total amount of power that the array can produce. Utilization of the array will be around 25% of total energy that can be created. That calls for 4 times more panels to achieve the same. 4 times more racking mounts also...you see where i am going. For that cost, you might as well pay only for a quarter of the panels and racking system and be left with 3 times more money to get a proper setup with the inverter and batteries,or a all in one solar generator. Also respect high dc voltage that h6 inverter needs from panels.There are some other things to factor like 550$ price for a h6 inverter, warranty questionable as the seller says that they will honor a replacement only if it was used with their panels. I still think about it here and there, and i might buy one and do this, but only because i will entertain myself working with it and call it a hobby project ,regardless of poor or not resilient project. Same way that i spend money on fish and supplies on my aquarium even if i don't have to. Situations may be different with you as far as money available,time,and cost of electricity. Definitely this will not be a cheat way of having direct dc air conditioning without batteries, charge controller and bms and all that stuff.

 

[Eri]

Hi @Eri, did you end up trying this? I'm very interested in your experience because I want to do the same thing. Were you able to run your air conditioning system from the H6 without batteries? Any learnings from the experience you could share with me? Did any equipment get damaged? Thanks very much for your reply!

Also wanted to add that for an emergency perspective, like our hurricanes in Florida, while you have a grid tied system installed already, this will be a good set and forget redundancy system to get some power for fridge and small 9000 btu system. Just tap to the existing system solar output and avoid having to redo the whole inverter with a hybrid. For daily use, in my opinion, the cons are greater than the pros. Let me know if you pull the trigger on this project, and happy to share my way below average knowledge on solar and off grid

 

[beesley]

@Eri, I want to thank you for the extremely helpful analysis you have provided in both of your replies. I'm persuaded that a batteryless system is not the practical or thrifty solution that I was hoping it would be. It was exciting to watch Mr. Beene pull off a proof of concept with the H6 in the YouTube video you shared, but your additional research brings me back to earth, so to speak. (I was about to write that it is "grounding", but I'm sure that bad pun will provoke some justifiable eye rolling.) Like you, I may try it out anyway in the future for the sheer fun of it, but for now I'm going to buy some batteries. Thanks again for spending your valuable time providing the thoughtful analysis!

P.S. @Electrovet, reading your posts, I instantly felt an affinity and solidarity toward you and am disappointed by the abuse you experienced on this forum. I share your point of view with regards to communication and feel the need to say so. You mentioned being in the ER and preparing for the end. I wish you peace and all the best, friend!

 

[Gadget]

Hi all, i dont mean to interrupt this thread but i have a question about the delta H6 hybrid inverter.

How do you disable the power factor correction?

or if thats not possible.

How does it work?

Ive set the reactive power parameter to 0% and Cos phi at 1. I was running it connected to my 48v sine inverter backcharging and feeding loads on an array running 9.5A at 405v and it displays 4721W. The array is only rated at 3800W so i know its trying its magic to come up with the other 1kw.

Other than that its a fine inverter but i dont need it blowing up my 48v inverter trying to inject power out of phase with it. Thats just asking for trouble. Theres gotta be a way to turn the feature off or trick it into being mostly inactive. I tried different numbers for cos phi and reactivepwr and it actually got worse.

Any ideas would be most appreciated.

 

[Gadget]

Update:
Interesting inverter. So i tried moving the parameter cos phi and reactive%. These settings both affected the *reactive power* amount as displayed on the inverters meter. Sad thing was, it only went up. The lowest i can get it to read is 300-500w range. I do this by setting cos phi to .99 and reactive pwr to 0%. The reactive power meter does go up as more solar energy is available. Its crazy they dont have an off setting for this. I wouldnt bother with it but im not connected to utility. Im off grid and i fear its interacting with my battery inverter in a negative way. My power factor as read by this inverter is +.90 to +.95 anyway and doesnt need correcting.

Its strange how inverter designers would add this feature and not one peep about it in the manuals. Only do they list the parameters in the manuals with no reference as to how they work or behave. Im guessing they essentially add or subtract timing distortion to otherwise perfect sine wave to compensate for leading or lagging current wave but i dont know for sure.