Honda EU2200i to Supplement Solar Charging

[mstgkillr]

Unfortunately, I am on Day 11 after receiving a direct hit from Hurricane Ian. Still no utility power, but I haven’t lost power from my Tesla solar/Powerwall system! Super impressed!

The last two days have been less than ideal for solar production, so I’m considering some type of generator supplementation. I have a Honda EU2200i. What do I need to do… suicide plug, transfer switch, etc? There has to be something!

 

[CrazyRabbit]

Best to just use extension cord.
You will not be able to charge batteries. I do wish someone would make solar “injector” for generators, where you can set the load on the generator.

 

[BGbreeder]

On the bright side, you made it through Ian, and your solar/powerwalls are working. Congratulations. Sorry that such a beautiful area got hit.

The best, and realistically only way at the moment, to use your Honda EU2200i is to run extension cords to your biggest loads to push off the loads from your solar/powerwalls. That will free up solar power to do more Powerwall recharging.

Combining a generator to a Powerwall requires some sort of feedback from the Gateway/Powerwall to tell the generator that the batteries need have the generator production throttled / turned off. At the moment there isn't one. There is also the small matter that your EU2200i is a 120V inverter generator, so it has the potential for odd voltage behaviors if you had it in tandem with a Powerwall. Phase matching might be an issue, and you could end up frying lots of things.

All the best,

BG

 

[jjrandorin]

Unfortunately, I am on Day 11 after receiving a direct hit from Hurricane Ian. Still no utility power, but I haven’t lost power from my Tesla solar/Powerwall system! Super impressed!

The last two days have been less than ideal for solar production, so I’m considering some type of generator supplementation. I have a Honda EU2200i. What do I need to do… suicide plug, transfer switch, etc? There has to be something!

Glad to hear you are ok, and that your system is at least helping you have power for stuff you need. I am not the most technical user here by any stretch, but I am almost positive there is no "approved" way for your generator to charge your batteries. Even for people who have both a generator and solar + powerwalls, its setup in such a way that if the solar + powerwalls can no longer provide power, THEN the generator comes in (either manually, or automatically, if its setup that way).

Keeping in mind that I mentioned I am not the most technical user here, it seems to me that you would just use your generator the same way you normally would, completely ignoring solar + powerwalls. Perhaps run a couple of plugs to your fridge or something, directly from the generator, etc.

Good luck, hope things return to normal for you soon!

Edit: @BGbreeder beat me to it, as I am making the same basic suggestion of running some loads directly from the generator if possible, like a fridge etc.

 

[jjrandorin]

@CrazyRabbit , most of the time when people mark disagree on something I say, I understand why. In this case, Im really unclear on what I said that might draw that response. If I said something incorrect, can you fill me in?

 

[CrazyRabbit]

@mstgkillr , I understand your production the last two day is poor and your powerwalls are drained. With good solar production, it can help to run your big loads during the day while solar is producing, this way you can avoid the round trip efficiency losses. When living on batteries and solar your behaviors, when you use electricity, need to change.

 

[CrazyRabbit]

@CrazyRabbit , most of the time when people mark disagree on something I say, I understand why. In this case, Im really unclear on what I said that might draw that response. If I said something incorrect, can you fill me in?

It was your edit, I said use a extension cord did I not.

 

[Watts_Up]

What type of Solar Inverter Charger do you have?

Some inverters have specific Auto Generator Start terminal pins, also called 'dry contacts' (meaning they are not energized).
This allows to automatically start and stop the generator, depending of the state of charger of your batteries.

Otherwise the approach used to connect a generator is to select which load
you want to connect to the generator using a separate subpanel and a transfer switch.

There are some interesting discussions on the DIY Solar Forum, such as the following.

How to hook up a generator?

I'm off grid. Do I need an automatic transfer switch if ao what one did you like? What about an anti reverse zener diode like my combiner box has? Lets say solar is doing a poor job at charging on a cloudy day, it would be nice for the genny to be able to charge the batteries at the same time...

diysolarforum.com

Note: Maybe in your particular case, as temporary fix, you could use some power cord to connect
directly your refrigerator and some lighting to your generator.

Note: About the 'suicide plug', well the cord with energized pins coming from your generator
will be exposed when not plugged into a wall receptacle, which is risky.
And you absolutly need to disconnect your main circuit breakers from the grid.
So this is certainly something not recommended.

 

[cali8484]

Unfortunately, I am on Day 11 after receiving a direct hit from Hurricane Ian. Still no utility power, but I haven’t lost power from my Tesla solar/Powerwall system! Super impressed!

The last two days have been less than ideal for solar production, so I’m considering some type of generator supplementation. I have a Honda EU2200i. What do I need to do… suicide plug, transfer switch, etc? There has to be something!

As others have mentioned, it would be easiest to run an extension cord from the generator. BTW, did you ask Tesla what you should do?

This is exactly why people to need to be able to charge their home batteries from a generator in off-grid situations.

 

[BGbreeder]

Don't get me wrong, I would love to be able to add a generator as an additional charging source for my Powerwalls, but I can see that there are significant issues with both power quality/voltage regulation/frequency regulation, from generators in general, and that there is currently no mechanism for the Gateway to taper or shutoff the generator as the Powerwalls approach 100% SoC, and have a more limited ability to accept charge.

My bottom line is that while some of the aforementioned issues could be addressable for some generators, the feedback mechanism to have the Gateway shut down the generator doesn't currently exist. In addition, I would hate to put a substantial investment in energy generation and storage at risk because there was a dimension that I have not /did not anticipate.

I think running extension cords is the optimal solution today.

All the best,

BG

 

[h2ofun]

As others have mentioned, it would be easiest to run an extension cord from the generator. BTW, did you ask Tesla what you should do?

This is exactly why people to need to be able to charge their home batteries from a generator in off-grid situations.

If my batteries die, then my whole house generator kicks in. No reason to add the complexity for charging batteries from generator, I will just wait until the sun comes out again

 

[GWord]

Unfortunately, I am on Day 11 after receiving a direct hit from Hurricane Ian. Still no utility power, but I haven’t lost power from my Tesla solar/Powerwall system! Super impressed!

The last two days have been less than ideal for solar production, so I’m considering some type of generator supplementation. I have a Honda EU2200i. What do I need to do… suicide plug, transfer switch, etc? There has to be something!

As others have said, the safest, non-kluge way is to power your loads directly with cords. The Powerwalls and your solar inverters expect 240V split phase to achieve a phase lock. Your Honda isn't going to provide that.

The only way I could really see it hypothetically working is to rectify the EU2200i's output to DC with a current limiter to simulate a 1.8kw solar array and wire it into one of the MPPTs. But that's a "Mr. Science" project for sure.

 

[GWord]

If my batteries die, then my whole house generator kicks in. No reason to add the complexity for charging batteries from generator, I will just wait until the sun comes out again

Also there's a 10% round trip efficiency penalty to go from generator to Powerwalls back to house loads. To your point, skip the middleman and enjoy an extra 10% in usable energy.

 

[cwied]

Also there's a 10% round trip efficiency penalty to go from generator to Powerwalls back to house loads. To your point, skip the middleman and enjoy an extra 10% in usable energy.

One thing to consider, though, is that the generator doesn't run efficiently when providing only a little power: https://www.researchgate.net/figure/Diesel-generator-efficiency-curve_fig4_276033446
Judging from this particular graph, this effect could easily outweigh the 10% loss from the round-trip to the Powerwalls.

 

[BGbreeder]

One thing to consider, though, is that the generator doesn't run efficiently when providing only a little power: https://www.researchgate.net/figure/Diesel-generator-efficiency-curve_fig4_276033446
Judging from this particular graph, this effect could easily outweigh the 10% loss from the round-trip to the Powerwalls.

That is for a large diesel, but the concept applies generally for traditional generators that they are the most efficient at around 75% loading. (But not very efficient overall at converting hydrocarbon energy to electrical energy.)

This cites the EU7000i as 19% efficient at full load, based on manufacturer data, while a larger diesel came out at 27% efficient.


All the best,

BG

 

[RKCRLR]

I don't know how your solar/Powerwall is wired to your panel so this may not work for you.
I use an interlock switch on my main panel for my generator similar to this:

https://www.amazon.com/Generator-Interlock-Cover-Frame-Breaker/dp/B08V8FJKLZ/ref=asc_df_B08V8FJKLZ/?tag=hyprod-20&linkCode=df0&hvadid=475818912700&hvpos=&hvnetw=g&hvrand=11637074397558933380&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032446&hvtargid=pla-1185222640456&psc=1

You hardwire a receptacle for the generator to a breaker in your main panel. This breaker has to be adjacent to your main panel breaker. It physically prevents you from having both your main breaker and generator breaker turned on at the same time. An advantage to this is you get to select which circuits you want to have powered by the generator by turning the other circuit breakers off but it is up to you to make sure you don't overload the generator and trip the breaker. But you'll need a 240v generator for this.

 

[CrazyRabbit]

Make sure the interlock kit is certified; UL, ETL or etc. kit should include a generator breaker hold down device. Personally I would only use the one made by the mfg of your panel.
Now there is nothing to stop you from making a custom 120v cord to go to your generator receptical, you would need to turn off all 240v circuit breakers. Now if you but the same phase to both legs of your panel the 240v stuff would see zero volts, still be hot but will not work.
I bought a 12kw dual fuel generator and installed interlock kits in both my panels. Also got three 100 lb propane tanks. Need to get another.

 

[cali8484]

If my batteries die, then my whole house generator kicks in. No reason to add the complexity for charging batteries from generator, I will just wait until the sun comes out again

Good for you but if you are in Cape Coral like the OP then a whole house generator may have been flooded out by Ian and no longer works. Portability can be important for various reasons.

 

[getakey]

Unfortunately, I am on Day 11 after receiving a direct hit from Hurricane Ian. Still no utility power, but I haven’t lost power from my Tesla solar/Powerwall system! Super impressed!

The last two days have been less than ideal for solar production, so I’m considering some type of generator supplementation. I have a Honda EU2200i. What do I need to do… suicide plug, transfer switch, etc? There has to be something!

How many PWs do you have? Were you able to run the AC most of the time?

 

[cali8484]

This cites the EU7000i as 19% efficient at full load, based on manufacturer data, while a larger diesel came out at 27% efficient.

For comparison, commonly available PV panel cells have even lower efficiency (~16%). Even the latest Perovskite cells only gets to 20-24% in the labs. Lots of wasted energy everywhere